Following more than a decade during which the reality of Pannotia was widely accepted, the existence of this Ediacaran supercontinent has come into question. This is due largely to advancing geochronology, which suggests that the supposed landmass had begun to break up well before it was fully assembled. Paleomagnetic data from this time interval have been used to both support and refute the existence of Pannotia, but are notoriously equivocal, and proxy signals of Ediacaran-Cambrian supercontinent assembly and breakup, although collectively compelling, can be individually challenged. Efforts to detect the mantle legacy expected of supercontinent amalgamation, however, are more compelling, and support large-scale mantle upwelling in the wake of Pannotia assembly. So, irrespective of whether Pannotia was a supercontinent or not, its assembly appears to have influenced global mantle convection patterns in a manner consistent with one. In the context of the supercontinent cycle, the question of Pannotia’s existence is of fundamental importance since it is central to the nature, duration and evolution of the cycle, it dictates the cycle’s geodynamic pathway from the breakup of Rodinia to the assembly of Pangea and, more crucially, it queries whether a full-blown supercontinent is needed to drive the cycle from one iteration to the next.

The Variscan belt of western Europe is characterized by the deformation of an anomalously wide continental passive margin, located in northern Gondwana, that acted as the lower plate during the upper Devonian – Carboniferous Variscan collision. Another feature in this collisional belt are the unrooted “allochthonous complexes” with lower crust and mantle rocks associated with dismembered ophiolite-like rocks, classically interpreted as sutures of putative oceanic realms (Rheic and/or Paleo Tethys oceans).

Many models have been built in the past decades to explain the architecture of the Variscan belt, generally using oversimplified geometries for the passive margin. When continents break apart, the lithosphere is thinned by stretching and “necking” through time. In rifted margins, the lower and upper continental crust become coupled and embrittled, causing major faults (i.e. extensional detachments) to propagate into mantle depths, and leading to mantle uplift. This process, “hyperextension”, is increasingly documented worldwide in recent passive margins and it may also be accompanied by magmatic activity derived from the decompression of the lowermost crustal components or even the mantle.

Two episodes of partial melting in lower crustal and/or mantle rocks can be identified during the long-lived evolution of the northern Gondwana passive margin, during Ordovician and lower Devonian, and can be associated with the margin stretching linked to ridge subduction. Inversion of a complex hyperextended margin depicting key magmatic features may explain most of the characteristics that can be observed nowadays in the West European Variscan Belt, including the unrooted nature of the complexes.

During Ediacaran to earliest Cambrian times, the Cadomian Orogen was formed on the periphery of the Gondwana supercontinent. The orogenic belt was structured in the geotectonic style of the recent western Pacific region. Cadomian arcs and marginal basins aged at c. 570-538 Ma were linked to an intense recycling (remelting) of crustal units of the West African and the Sub-Sahara cratons. The existence of an Upper Ediacaran glacial period at c. 566-560 Ma places the origin of the Cadomian orogen in high latitudes of the southern hemisphere. Due detrital zircon populations from Cambrian strata the Cadomian orogen shared a part of its geotectonic history with East Avalonia. Because of the split-off of Avalonia from Gondwana mainland the Rheic ocean became opened. Provenance studies point to a docking of East Avalonia onto southern Baltica at c. 430 Ma and to a closure of the Rheic Ocean at c. 430-420 Ma. In the aftermath, the re-opening of a narrow Rhenish Seaway happened in mid-Devonian time. Deposits formed on the Rheno-Hercynian margin display sedimentary supply from southern Baltica, while most East Avalonian sources were buried and not available for erosion. Siliciclastic shelf deposits of Saxo-Thuringia were derived from Cadomia and its West African hinterland. As a result of the closure of the Rhenish Seaway the old suture of the Rheic Ocean was overprinted. Pangea´s internal suture is complex and became formed by closure of two oceanic basins and thus, forms a “cryptic” structure.

The geochemistry of sedimentary sequences allows the recognition of patterns and shifts in geodynamic settings. On active margins, the contribution of these sequences to arc magmatism through processes such as subduction erosion is being actively investigated. Thick sequences were sedimented along the Gondwana margin between the Ediacaran and Cambrian times. These preserve the evolution of their sources, which are closely related to the activity of arc systems and nearby continental areas. In the Variscan Belt, the SW Iberian Massif (Ossa-Morena Complex) preserves a section of an arc whose evolution is followed through the characterisation of subduction-related magmatism and the coeval metasedimentary record, during a time interval spanning almost 100 Ma. This study reveals that arc magmatism was linked to synorogenic sedimentation in a complex and poorly explored way. In this sense, arc recycling is shown by the isotopic (Nd) equivalence between the sedimentary series and the mafic magmatism related with subduction onset (pre- to 602 Ma) preserved in this section. Early magmatic pulses of arc building (c. 602-550 Ma) are characterised by their adakitic signature related to the melting of a significant volume of slab-induced sediments, probably favoured by subduction erosion. Meanwhile, during late stages (c. 540-534 Ma), magmatism evolved towards greater mantle input associated with the progressive variation of the slab angle. This study provides a model for the petrogenetic and geodynamic evolution of the arc from the Ediacaran to the early Cambrian times, improving the accuracy of future paleogeographic reconstructions.

Vegetation cover poses a significant challenge in geological surveys. Utilizing plant chemistry to detect underlying geological features offers a non-invasive exploration tool. Here, we employ a novel approach in biogeochemical data analysis to distinguish between mineral deposits and bedrock void of mineralization. Different plant species and tissues exhibit distinct element compositions in a multivariate hyperspace, making direct comparisons in terms of absolute concentrations challenging. Our approach aims to overcome this traditional constraint by analyzing biogeochemical datasets irrespective of the specific species and tissue collected, as we will account for the physiological variations through data preprocessing. We use principles of compositional data analysis to transform biogeochemical datasets, enabling comparability across different sample materials and other plant datasets.

The corrected biogeochemical dataset for the sample type was analyzed using Linear Discriminant Analysis to identify element associations indicative of differences between samples collected over mineralized bedrock and those from rocks void of mineralization (barren). Results show differences in group means between samples sourced from pillow basalts and mafic rocks compared to their mineralized counterparts, distinguishing between mineralized and mineralization-free samples. For example, when comparing element ratios of Cu, Ca, and Rb to P and Sr, differentiation is observed across six distinct plant materials between barren pillow lavas and the corresponding mineralized bedrock.

The Pohjanmaa Belt in western Finland hosts orogenic Au deposits with enrichment in base metals, such as the Jouhineva Cu-Co-Au-Ag deposit (0.448 Mt at 0.811% Cu, 0.182% Co, 0.88 ppm Au, and 7.864 ppm Ag measured reserves). It is located 3 km NW of the Au-only Huhta occurrence along the same NNW-trending fault. We test if the different metal association in both deposits is related to temporally and structurally different mineralization events. Four deformation events are distinguished: D₁ formed a now EW- and NW-trending S₁, which is transposed during subsequent deformation; D₂ folded S₁ into a NW-SE to NNW-SSE trending S₂ crenulation cleavage; D₃ refolded S₂ into close to isoclinal folds and generated a NNW-SSE trending, axial planar S₃; D₄ formed a centimeter-spaced, EW-trending S₄ foliation. Huhta hosts syn-D₃ Lö-Apy-Au-Qtz veins with multiple stages of sulfide, arsenide, and sulfarsenide mineralization. Jouhineva hosts syn-D₃ Apy-Au-Ccp-Qtz and syn-D₄ Ccp-Au-Qtz veins. Titanite U-Pb and structural data indicate synchronous formation of Lö-Apy-Au-Qtz veins in Huhta and Apy-Au-Ccp-Qtz veins in Jouhineva at 1850-1820 Ma during D₃. Thus, the different mineralogy and metal endowments formed during the same tectonic event during the Svecofennian Orogeny. Only Jouhineva hosts additional Cu-Au mineralization that formed later during the retrograde evolution. The different metal association in both occurrences may be explained by different metal and fluid sources and compartmentalized fluid migration, distinct mineralization events during the 30 m.y. evolution that cannot be resolved by titanite geochronology, or different precipitation mechanisms although host rocks and PT conditions are similar.

The Gorno mining district is an example of Mississippi Valley-type (MVT) deposits in the Italian Orobic Alps. Spanning an area of ~100 km², it consists of stratabound Zn-Pb-Ag (± fluorite ± barite) mineralization hosted in a lower Carnian stratigraphic succession. Despite Vedra Metals S.r.l.´s acquisition of the exploration license for the deposits has reignited an economic interest, an updated metallogenic model has yet to be developed.

In the carbonate host rocks at Gorno, a complex series of dolomitization, silicification, brecciation, dissolution, and cementation occurred. Microthermometry of primary fluid inclusions in sphalerite and fluorite, alongside sphalerite trace-element geothermometry, indicates formation temperatures ranging from 80 to 140 °C (mean value: ~100 °C). Moreover, fluid inclusion microthermometry and micro-Raman spectroscopy document the involvement of high-salinity brines (up to ~25 eq.wt% NaCl) and gaseous hydrocarbons (e.g. CH₄) in ore deposition. Isotopic signatures from ore-related carbonates for carbon (0.5 to 2.5 ‰ PDB), oxygen (-6.6 to -12.1 ‰ PDB), and strontium (0.70840-0.70943) indicate that the ore fluid was likely seawater modified through interaction with the underlying Permian clastic sediments and/or with the metamorphic basement.

The presence of sulfide bodies in association with organic-rich shales implies a notable role of organic carbon in ore deposition. Organic matter and associated hydrocarbons likely served as reactive barriers, leading to the reduction of the ore fluid and initiating the precipitation of sulfide minerals.

Efficient transfer of S and chalcophile metals through the Earth’s crust in arc systems is paramount for the formation of large magmatic-hydrothermal ore deposits and can strongly affect the Earth’s climate. The formation of sulfide-volatile compound drops has been recognized as a potential key mechanism for such transfer but their fate during dynamic arc magmatism remains cryptic. We report evidence of compound drops preserved in the active Christiana-Santorini-Kolumbo volcanic field. The observed compound drops are micrometric sulfide blebs associated with vesicles trapped within silicate phenocrysts. The compound drops accumulate and coalesce at mafic-felsic melt interfaces where larger sulfide ovoids form. These ovoids are subsequently oxidized to magnetite during sulfide-volatile interaction. Comparison of metal concentrations between the sulfide phases and magnetite allows for determination of element mobility during oxidation. The formation and evolution of compound drops is an efficient mechanism for transferring S and chalcophile metals into shallow magmatic-hydrothermal arc systems.

There is still no consensus in the literature concerning the most critical processes for rare earth elements (REE) enrichment in carbonatite rocks. One-third of alkaline‑carbonatite complexes are associated with ultrabasic and basic rocks. Some basic rocks contain similarly high concentrations of LREE as carbonatites where perovskite [CaTiO3] is responsible for this enrichment. Carbonatites form later than ultrabasic and basic rocks, and carbonate melt penetrates into silicate rocks and reacts with them. The reaction was named “antiskarn reaction”. Until now there is no detailed study on whether perovskite from pyroxenites can become a source for REE enrichment of carbonatite melt during antiskarn reactions.

We studied three ultrabasic-alkaline carbonatite complexes from the Kola Alkaline Province (Russia) to focus on the comparison of REE contents from pyroxenites and carbonatites and the fate of perovskite. Ultrabasic/basic rocks and carbonatites show the same broad range of REE contents. In most analyzed pyroxenites, perovskite is the main REE carrier mineral. For carbonatites/phoscorites, apatite and calcite are the minerals that control rocks' REE enrichment. Several samples show considerable variations of REE concentrations related to carbonatite infiltration, sometimes even at a very low local scale (mm²). If perovskite was present it was replaced near the carbonatite melt by titanite that has much lower REE contents. Calcites and apatites from the infiltrated carbonatite are highly enriched in LREE but show large local element variations. Thus, we propose that LREE liberated by the perovskite replacement can be dissolved in the carbonatite melt and transferred to its crystallizing minerals (calcite, apatite).

The reconstruction of ancient environments is one of the major goals of palaeontology. One of the most important factors in shaping the environment is the atmospheric concentration of carbon dioxide (CO₂). A commonly used praxis to assess Deep Time CO₂-concentrations is via a dependent proxy. The aim of this study was to estimate concentrations in the late Pliocene using the ratio between stomata and epidermis cells (Stomatal Index, SI) on the surface of Ginkgo adiantoides leaves as a proxy. In order to establish a reliable reference for the quantitative relationship between CO₂ concentration and this SI, measurements ideally should be done with specimen grown across a wide range of known CO₂ concentrations. Additionally the reference taxon has to be as closely related to the fossil taxon as possible since the SI at a given CO₂ concentration and its reaction to changing concentrations varies greatly between different species. Due to these constraints the baseline for the present analysis was calculated using Ginkgo biloba, the closest living relative to the now extinct Ginkgo adiantoides. For this purpose leaves were taken from herbarium archives collected across the last 150 years, as well as leaves freshly collected in 2023 and 2024, together with abundant data from the literature. In order to visualize the epidermal cells and stomata a number of microscopic techniques were used. Utilizing this modern calibration dataset CO₂ concentrations were estimated based on Ginkgo leaves from the Late Pliocene floras of Frankfurt am Main and Ruppach-Goldhausen (both Germany).

The study of natural climate archives is a significant method to understand past environmental conditions and depositional processes. Investigating Central German lignite is particularly suitable, as it serves as an environmental and climate archive, formed from Tertiary mires and their ecological and climatic conditions.

The petrographic composition of lignite is greatly influenced by the plant communities that formed the paleo-mires, serving as direct indicators of the climate and environmental conditions of that era. These plant communities developed in cyclic sequences, progressing from coniferous swamp forests and angiosperm-dominated peatlands to reed marshes and pine woodlands, culminating in raised bogs.

In this contribution, detailed petrographic and facies analyses of lignite seams are provided to show insights into the physicochemical and ecological conditions of these ancient marsh sequences. Field mapping and core logging at the open-pit mines Profen and Vereinigtes Schleenhain in Central Germany were conducted. Taken samples were analysed macropetrographically, as well as microscopically in terms of maceral analysis and moor facies analysis.

The resulting depositional model reconstructs the development and disturbances of the paleo-mires, revealing external environmental influences. It demonstrates the sequence of moor facies cycles and identifies areas with peat fires or the drying out of the marsh. This includes information on plant communities, groundwater levels, oxygen and nutrient availability, and climatic conditions during deposition. By correlating this information throughout different parts of the Central German lignite basin, new insights into its depositional model are provided.

Geophysical data from the Liguro-Provençal Basin shows prominent margin asymmetry but the nature of the crust, especially in the northeastern part of the basin, remains unclear. The basin formed at the junction of the northern Apennines and the western Alps due to the rollback of the Calabrian-Apennines subduction zone in the Oligo-Miocene. The opening of the basin was accompanied by counter-clockwise rotation of the Corsica-Sardinia block relative to Europe with the basin widening southwestwards. Recent weak compressional earthquakes offshore within the basin suggest possible basin inversion due to the ongoing Africa-Eurasia convergence. An insight into the crustal structure of the basin is therefore the key to understanding these recent processes. To this end, we compiled existing geological and geophysical data, including new data from the German project “Mountain Building Processes in Four Dimensions” (4DMB), to constrain the crustal and sedimentary thicknesses throughout the basin. Moreover, we derived kinematic parameters of extension using regional tectonic reconstructions and used the coupled ASPECT and FastScape geodynamic code to model the opening of the basin in its northeastern (Corsica – Provence) and southwestern (Sardinia – Gulf of Lion) parts. The comparison of the geodynamic models and geophysical data suggests: 1) the extent of oceanic crust in the Liguro-Provençal Basin did not reach as far north as previously presumed; 2) rift-related structures are possibly being reactivated offshore to the northwest of Corsica. We also present new constraints on the lateral extent of rifted continental crust and exhumed mantle and evolution of the basin through time.

The Rodada Formation is one of the Ordovician sequences that crops out in the eastern domain of the Iberian Central System (Central Iberian Zone, CIZ). This formation is mainly composed of Middle Ordovician (Darriwillian) fine-grained shales. An isotopic study (Sr and Nd) in 15 shale samples of this formation reveals negative εNd₍₄₆₀₎ values, which indicate a high cortical affinity and relatively older isotopic signatures (T_DM= 1.6-1.8 Ga). These Nd model ages prove to be older than those associated with Ediacaran and Cambrian sequences in southern CIZ. Altogether, T_DM values represent an inverse chronological evolution compared to the ages of the stratigraphic sequences. The causes for this evolution are yet unclear, however it should be considered that, during the Middle Ordovician, the North African margin of Gondwana shares the characteristics of a passive margin affected by a pronounced extension. In this margin, the location of the CIZ is subject to an extensive debate. Even so, it is commonly accepted that its sedimentary sequences were deposited in an elongated section of the continental shelf adjacent to the Sahara Metacraton and Trans-Saharan Orogen. The evolution followed by the T_DM record may be compatible with a progressive variation in the source areas and their shifting towards regions closer to the West African Craton. In addition, it may be also explained by an increased exposure or progressive exhumation of the cratonic domains of northern African continent. An extended post-glacial period may have contributed to both processes, either by the retreat of the ice sheet or by the subsequent isostatic compensation.

To explore fault-bound hydrothermal systems, knowledge about fluid conduits and the (isotope-) geochemical composition of the geothermal water is necessary. At the hydrothermal vein deposit of the former Schönbrunn fluorspar mine, fluid conduits in the depth between the 293 and the 533 m level were outcropped. Attempts at utilization for deep geothermal energy failed in 1997, because the mine was flooded. The thermal water outflow of the most active fluid conduit, outcropped at the 533 m level was 1 m³ min^-1 and the temperature was 35,7°C. The fluid conduit is controlled by the intersection of a fault bundle of several NNW-SSE and NW-SE striking faults. The horizontal length of the intersection area is about 400 m. A geothermal anomaly exists at the segment of the intersection. The quartz-fluorite bearing mineralization (primary) was redeposited by carbonate-sulfide mineralization with depth.

Research on unpublished water and gas samples (96 and 115 data sets, respectively) from the so called “spa” at the 453 m level of the Schönbrunn mine was carried out by time-series measurements (weekly sampling rate) to investigate 1) composition and origin of the thermal water, 2) reservoir temperature via geothermometry, and 3) potential hydro- and gas-chemical effects of regional swarm seismicity. We revaluated the results and collated them with new findings of the Neumühle thermal water (Prause et al., session 4b) in order to develop deep geothermal energy projects at crystalline rock areas in Western Saxony.

The KTB site near Windischeschenbach is one of the best characterised locations of continental upper crust worldwide. The superdeep boreholes represent a unique in situ underground research laboratory in Europe, allowing research into the sustainable utilisation of the crystalline subsurface for the energy and heat transition.

The GEOREAL experiment aimed at hydraulically stimulating the fractured crystalline metamorphic basement rocks at 4 km depth and to minimise the potential risk of induced seismicity by real-time control of injection parameters. The KTB infrastructure allowed to inject 600 m³ of water into the 4 km deep KTB pilot hole, while the main borehole (only 200 m distant at the surface) was used for seismic monitoring.

Fluid injection took place during 6-15 November 2023 through the stuck GEOREAL packer pressurising the open borehole section at the depth interval of 3.85–4 km. Flow rates were variable (10– 220 l/min). No induced microseismic events were detected. Pressure data, monitored at the well head of the pilot and main borehole, was analysed in conjunction with recordings from a year-long injection experiment into the same formation performed in 2004/5. The hydraulic parameters show similar values as previously obtained. The observations provide more detail on the hydraulic connection at depth between both boreholes. The GEOREAL experiment had to be stopped prematurely due to a leak in the casing cement. Further activities at the KTB deep crustal lab are underway, substantiating the potential of petrothermal research at the KTB deep crustal lab after 30 years of operation.

The E4Geo Project aims to explore fault-bound hydrothermal systems associated with the hidden granite pluton of Eichigt-Schönbrunn in the Vogtland region of SW Saxony, Germany, for potential use as deep geothermal reservoirs. Evidence for enhanced geothermal gradients in this region has existed for several decades, but attempts at utilization for energy production and heating have thus far been limited.

We aim to constrain 1) composition of the thermal water, 2) reservoir temperature, 3) the effects of water-rock interaction, 4) fluid residence times and recharge rates, 5) contributions of radioactive decay to the local heat source, and 6) approximate heat flux. For this purpose, we present new geochemical data from time-series measurements performed on local water samples from regional thermal springs at Neumühle/Vogtland, which are contrasted with samples from the nearby Erzgebirge (Georgsquelle/Wiesenbad, Silbertherme/Warmbad) and Fichtelgebirge (Siebenquell/Weissenstadt) regions.

Geochemical time-series measurements of major cations and anions allow us to estimate reservoir temperatures via geothermometry and to characterize the chemical nature of the thermal waters, including potential scaling effects that may occur during operation of a geothermal plant. Potential hydrochemical effects of rainfall and regional swarm seismicity are likewise examined. Stable isotope analyses (δ¹⁸O and δ²H) of water samples are utilized to decipher the origin of thermal waters and to evaluate potential mixing with meteoric components. Lastly, specific activities of nuclides from the ²³⁸U and ²³²Th decay series are applied with ⁴⁰K in preliminary heat flux estimates and identification of ground water types, while residence times are approximated from ¹⁴C and ³H.

The valley of Geysers, is a multi-habitat environment for microorganisms, ranging from moderate to extreme environmental conditions within short distances. The aim of the present study is to characterize and compare the microbial communities in variable habitats: thermal water pools, outflow transect from a geyser to the Geysernaya river, river bed samples and a recently reactivated geyser in the river buried in landslides in 2007 and 2014. The study combines organic geochemical and geomicrobiological approaches with hydrochemical background data.

The different microbial habitats exhibit a wide range of different cell membrane biomarkers. Hot habitats are dominated by markers for archaea with lower abundances of bacterial biomass, indicating the presence of extremophiles in these habitats. Along the transect from a geyser to the river, the microbial community is dominated by bacteria with specific markers pointing to photosynthetic microbs. The river bed samples show only small amounts of bacterial biomass. A closer look at the taxonomy of the microbial communities of the different locations supports the clear difference between the communities influenced by hot and temperate water. Along the transect, the two sample at the upper end of the outflow (closer to the geyser, 66-84°C water temperature) show many extremophilic archaeal and also bacterial taxa, while the lower samples (around 32-39°C temperature) are characterized by mesophilic bacterial taxa with even some cyanobacteria. Initial result indicates the existence of unknown species within the communities. Overall, the microbial communities show a high spatial variability determined by the thermal conditions of the different life habitats.

Laterite ore deposits in Brazil and other tropical countries contain approximately 70 % of the world’s Ni and Co resources. High energy and/or reagent costs, accompanied by expensive equipment costs, are generally incurred when recovering Ni and Co via pyrometallurgy or high pressure acid leaching. Several acidophilic bacteria are able to use elemental sulfur as electron donor and couple the oxidation of sulfur to the reduction of molecular oxygen and/or ferric iron, and are thereby generating sulfuric acid and dissolving distinct Ni- and Co-bearing mineral phases partly via chemical reduction, e.g. Mn-oxides. Reductive bioleaching of laterites with acidophiles has been described for anaerobic as well as aerobic conditions. Stirred-tank bioreactor and percolation column laboratory experiments were carried out in the BioProLat project to test various samples from three different laterite deposits in Brazil and to optimize parameters including pH, temperature, aeration, and finding the most suitable bacterial consortium for the bioleaching of Ni and Co. Stirred-tank laterite bioleaching experiments starting at pH 1.5 under aerobic conditions with a consortium of different Acidithiobacillus thiooxidans strains resulted after 15 days in maximal extraction of 83 % Co and 83 % Ni, for 10 % (w/v) pulp density of a laterite sample. Column bioleaching with another laterite sample achieved 95 % Co and 66 % Ni extraction after one month. Eventually, the optimized process will be upscaled, transforming unexploited laterite ores and limonite stockpiles into valuable resources.

Constant depletion of high-grade metal deposits focuses mankind’s attention on technology assuring efficient metal recovery from low-grade deposits. Biohydrometallurgy appears as effective, cost-friendly and environmentally benign technique for resource extraction from metal-bearing phases through microbial activity. Due to number of factors influencing final metal recovery, such as pH-Eh conditions, applied microorganisms, chemical and phase composition of bioleached ore, each deposit should be considered as individual case, and thus examined meticulously.

In this research heterotrophic bacterial strain Pseudomonas fluorescens was investigated in terms of metal bioleaching from polymetallic, organic-rich Kupferschiefer shale. Scrutiny involved two different Kupferschiefer samples, displaying various metal concentrations. Activity of Pseudomonas fluorescens was compared to the activity of Acidithiobacillus thiooxidans strain.

The 35-days-long bacterial incubations proved the effectiveness of Pseudomonas fluorescens towards metals leaching, especially in case of copper and molybdenum. In most cases Pseudomonas fluorescens resulted in more advanced metal solubilization within the solution compared to Acidithiobacillus thiooxidans. Differences between activity of those two strains involve not only metal leaching, but alterations of the shale surface as well.

Additionally, restricting organic nutrient for Pseudomonas fluorescens as potential way of optimizing was examined. Despite lower effectiveness in metal leaching as compared to well-feeded strain, noticeable metal solubilization was maintained. This could reflect either nutrient stress or possibility of obtaining organic carbon from kerogen particles present in both shale samples.

Conducted experiments highlight the role of Pseudomonas fluorescens in metal mobility from metalliferous shale and open the perspective of more detailed investigation of bacterial-mineral interactions and enhancing metal recoveries.

Acidophilic leaching microorganisms are of industrial interest to extract metals from ores. The effect of characteristics such as rugosity, charge, and composition on the colonization of bioleaching bacteria is not yet fully understood. Since cell colonization on pyrite (FeS₂) surfaces is highly heterogeneous, robust massive image analysis methods must be employed.

We investigated the effects of rational modifications of pyrite surfaces on early colonization and biofilm formation ability of bioleaching bacteria. We used confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), Raman spectroscopy, and field emission scanning electron microscopy (FE-SEM) with energy-dispersive spectroscopy (EDS) to characterize the surface of pyrite coupons polished to varying degrees. We further colonized the polished pyrite with three bioleaching strains: Leptospirillum ferriphilum, Acidiferrobacter SP3, and Acidithiobacillus ferrooxidans R1. After 24 h of colonization, samples were imaged using EFM, and massive sets of 176-384 images per replicate were analyzed and semi-quantified using custom-made Python scripts and open-source libraries to obtain the colonization density, area, and shape of cell colonies. The data suggest a slight increase in colonization area in medium polished samples in comparison to low polished ones, but a decrease on highly polished samples. However, Kruskal-Wallis test with multiple comparisons indicated no significant differences in other cell colonization parameters among the different samples.

Critical metals like gallium (Ga) and germanium (Ge) hold strategic importance in the development of modern technologies like optoelectronic devices, semiconductors, light-emitting diodes, and many more. The supply of these metals is not assured due to many reasons. Therefore, new sources and efficient recovery techniques needs to be identified. Thus, attention should be drawn to sources with very low concentrations of these metals which are usually neglected. This is due to high concentrations of contaminant metals and very low concentrations of critical metals. Thus, a highly specific, selective and sustainable process is needed. Siderophore assisted technology “GaLIophore” could be a solution. In GaLIophore, siderophore Desferroxamine B (DFOB) is used to selectively adsorb the metals Ga and Ge from industrial wastewater. DFOB is a highly selective molecule and forms a highly stable complex with Ga and Ge. Interaction of Ga and Ge with DFOB are quite unique and different from one other. Complexation of DFOB with Ge is preferred in acidic pH and presence of chloride ion. While Ga complexes with DFOB across the pH 3-9 and is also not affected by the presence of any anion. Furthermore, DFOB can be re-generated by the addition of excess of ethylenediaminetetraacetic acid (EDTA) at pH 3.5. This leads to the recovery of more than 90% of both the metals at the end and makes the process sustainable. Thus, this technology for the first time demonstrated a solution to recover these critical metals from low concentrated systems in a sustainable and eco-friendly manner.

Ion flotation process offers a sustainable way to separate and recycle critical metals from industrial wastewaters that often have low concentrations of target metals. There is a high demand for new flotation reagents which are preferentially environmentally friendly. Microbial biomolecules are an attractive alternative and we are exploring various biomolecules in this regards. The use of these biomolecules as flotation reagents in the ion flotation process can be termed as ‘bioionflotation’. This biotechnological approach for metal recovery from low concentrated waters is still dawning and more research is required to improve the selectivity and process efficiency. In this work, marinobactin (a suite of amphiphilic siderophores) was investigated as a flotation reagent for the separation of Gallium (Ga) from synthetic solutions. Amphiphilic nature of these siderophores and metal complexation ability make them an interesting molecule for an application in the flotation process. Single metal flotation test suggested the Ga recovery and marinobactin-Ga complexation in the collected concentrates was confirmed by HPLC. Further, effects of various operating parameters on the metal recovery and selectivity were studied. The flotation results of the mixed metal solutions (containing Ga and As at 1 mM concentration), showed 88% of Ga recovery and 11% of As recovery, at 0.25 mM marinobactin concentration at pH 4 and air flow rate of 20 ml/min. These results provide the basis to fully embrace the potential of novel bio-ion collectors in developing a highly synergistic process of bioionflotation for recovery of critical metals from low concentrated wastewater.

The surge in battery demand for both mobility and stationary applications necessitates a critical examination of the environmental impacts associated with battery material production and disposal. Key components such as cathodes, anodes, separators, and electrolytes contribute to environmental degradation throughout their supply chain, emphasizing the urgency for sustainable solutions. Circular economy principles offer a strategic framework for mitigating these impacts by promoting extended product lifecycles and increased utilization of recycled materials. This paradigm shift aims to minimize resource extraction and waste generation, thereby reducing greenhouse gas emissions, toxic exposure, and resource depletion. While challenges persist in achieving perfect circularity due to technical and logistical complexities, embracing the circular economy presents a promising avenue for enhancing sustainability in battery manufacturing and usage. The optimization of hydromechanical Li-ion battery recycling systems involves a multifaceted process encompassing material flow analysis and various mechanical, physical, and metallurgical processing units. The Simulation models utilizing advanced software aid in understanding material composition and flow dynamics, crucial for applying Design for Recycling Principles. Exergy calculation within a thermoeconomic framework further evaluate resource efficiency of the recycling route, and analytical techniques such as ICP-OES and XRD analysis play pivotal roles in identifying complex constituents and guiding process optimization. Regenerated lithium salt assumes integral significance in NMC battery production. This paper underscores the importance of efficient material recovery and recycling in sustainable battery production, emphasizing its critical role in meeting the demands of a greener future.

The late Carboniferous–Early Triassic Krkonoše Piedmont Basin in the northern Bohemian Massif was initiated as a fault-controlled basin during the waning stages of the Variscan orogeny and its transition to an intra-plate setting. The basin was filled with 9 formations of mostly red beds with a total thickness more than 2000 m, deposition was accompanied by extensive volcanic activity dominated by andesitic lava flows and ash-flow and ash-fall tuffs. The U–Pb detrital zircon geochronology on 17 samples taken up-section across the basin stratigraphy points to local as well as distant sources of detritus derived predominantly from the nearby Saxothuringian and Teplá–Barrandian units, with Archean–Paleoproterozoic, Ediacaran, Cambro-Ordovician, Late Devonian and middle–late Carboniferous age peaks. Furthermore, magnetic fabric of the red beds was analysed at 29 sampling sites using the anisotropy of magnetic susceptibility (AMS) method in order to understand both the syn- and post-depositional history of the basin. Five different fabric types were detected across the basin and interpreted in terms of random orientation of magnetic grains due to turbulent flow (Type 1), strong alignment of magnetic minerals representing depositional fabric and recording paleocurrent directions (Type 2), superposition of compaction strain onto pre-existing depositional fabric (Type 3), tectonic fabric formed due to small increments of regional strain (Type 4), and an anomalous, mineralogy controlled inverse fabric (Type 5). Altogether the detrital zircon ages and multiple magnetic fabrics reveal a long term and complex sedimentary and post-sedimentary evolution and inversion of the basin in the Pangea interior.

Results of a systematic study are presented combining U-Pb ages, Hf isotope data and shape parameters (length, width, aspect ratios, roundness, roughness, typology) of detrital zircon populations from low- to medium-grade greywackes of the Badenweiler-Lenzkirch Zone (BLZ), which is squeezed between high-grade gneisses of the Central and Southern Black Forest Gneiss complexes. Nine sample are investigated from three formations: Sengalenkopfschist, Schleifenbachschist, and Protocanites Greywacke unit, assumed to be deposited from the Early Ordovician to Early Carboniferous based on biostratigraphic record. This interpretation, however, is at odds with detrital zircon U-Pb ages, revealing robust maximum depositional ages between 368 and 378 Ma for rocks of all three units. Age spectra show peaks at 380-400 Ma, 480-500 Ma, 600-620 Ma, 700-750 Ma, 0.9-1.1 Ga, 1.8-2.2 Ga, and 2.6 Ga, and Hf isotopes a juvenile input at 380-400 Ma (εHf_t up to +5). The combined age-Hf data point to a similar provenance like the metamorphic rocks exposed in Southern Black Forest gneiss complex, hosting relics of different Gondwana-derived terranes, in addition to a Late Devonian arc-back arc system. Similar proximal sources are also indicated by the finding of abundant euhedral zircon grains with ages <550 Ma in all samples, and a significant overlap in zircon typology. The low degree of zircon roundness and roughness reflect sediment transport in water-saturated media, but in some samples has been significantly modified by post-depositional structural-metamorphic overprint, causing mechanical zircon peeling and chemical dissolution in contact with sheet silicates, in particular during garnet-forming dehydration-reactions.

There is no firm evidence for glaciation for over 1.5 billion years, i.e. from the Great Oxidation Event (or Episode) until the onset of the Cryogenian Period. By contrast, global glaciation became the predominant climate state for the next 85 million years, followed by a series of regional ice ages that culminated in the Ediacaran-Cambrian biological radiations. There is increasing evidence that each of these climatic events was preceded by a negative carbon isotope anomaly, potentially caused by imbalance within the global sulphur cycle and related redox and productivity feedbacks. In this presentation, I aim to outline the evidence for primary carbon isotope anomalies before transitions into glaciation at c. 720 Ma, c. 660 Ma, c. 580 Ma and c. 560 Ma, as well as similar isotopic events that have identical geochemical context, but for which no glacial deposits have yet been identified. Cryogenian-to-Cambrian carbon cycle elasticity reflects a distinct earth system state, which was likely related to a dynamically changing organic carbon reservoir, oxidation of which was coupled to sulphate and ferric iron reduction. Organic carbon likely became the dominant redox (and climate) capacitor in the exogenic earth system only once atmospheric oxygen ceased to be a limiting factor for the weathering of iron sulphide minerals. The extent to which sulphur cycle imbalance forced climatic and environmental change after the Cambrian explosion remains to be determined.

The terminal Ediacaran Urusis Formation of the Nama Group (southern Namibia and northwestern South Africa) is a fossiliferous, mixed carbonate-siliciclastic succession with numerous silicified volcanic tuff interbeds. Studies of the Urusis Formation have historically focused on the Swartpunt area of southern Namibia, where post-depositional thrusting associated with the Gariep orogeny transported and emplaced the Formation as a series of thrust plates, which abut autochthonous Nama Group deposits to the east. Over thirty years of geochronological, chemostratigraphic and paleontological investigations have made the Swartpunt area a key reference section for terminal Ediacaran chronostratigraphy. Recent geochronological data from an expanded succession, exposed on the border between Namibia and South Africa, have cast doubt on the interpretation that ash beds in the vicinity of Swartpunt record depositional ages, possibly due to zircon reworking. The resulting implications for the temporal calibration of global terminal Ediacaran chemostratigraphy, as well as confidence in the maximum reported uncertainty of radioisotopic dates across geological time, are numerous. However, alternative regional structural complications that may resolve these issues have not yet been fully considered. Here, we build upon foundational observations of structural tectonics in the Swartpunt area, combining high resolution geological mapping, outcrop and drill core stratigraphy obtained through the ICDP GRIND-ECT project, carbonate carbon isotope (δ¹³C_carb) chemostratigraphy, and new high precision radioisotope geochronology (zircon U-Pb chemical abrasion-isotope dilution-thermal ionization mass spectrometry, CA-ID-TIMS). We use these data to explore structural alternatives that may resolve the chronostratigraphy of the Urusis Formation without invoking insidious zircon reworking.

Marine carbonates are potential archives of geochemical proxies, such as U-Pb and Sr isotopes, which can be utilized in the reconstruction of past climate conditions and ancient seawater composition. The ability to confidently reconstruct environmental conditions in the past times is of great importance since they are linked with changes in the biosphere. For example, the Ediacaran-Cambrian transition was a period of time where significant evolutionary change modified the biosphere. An intact, continuous record of environmental conditions will help to understand better the timing, nature and sequence of events that preceded or accompanied such changes in biodiversity. However, carbonate rocks are susceptible to numerous post-depositional processes (such as: oxidative weathering, diagenesis, burial, lithification, deformation, dissolution and reprecipitation), which may alter the geochemical record. Additionally, detrital components may increase the complexity of the geochemical signature and the carbonate composition.

Thus, we have to understand and identify the presence or absence of such processes, before extracting meaningful geological information from these archives. Laser Ablation – Inductively Coupled Plasma – Mass Spectrometry (LA-ICP-MS), is a tool that offers spatial resolution when performing geochemical analyses, which may help to interpret the geochemical data. Here, we combine observations from U-Pb and Sr isotopic systematics supported by trace element abundances to identify domains that are indicative of post-depositional processes, over protracted time and variable in their extent.

Neoproterozoic Nama Group sediments in SW Namibia provide an example of the interplay between the deposition of clastics and carbonates that do not obviously follow the “rules” of sequence stratigraphy. The unconformity surface beneath the sediments is planar and extensive. Basal interbedded carbonates and coarse clastics are overlain by a massive influx of fluvial clastics (Kliphoek Member). These fine upwards and are overlain by fine grained clastics with interbedded carbonates and minor turbidite sands (Aar Member) that contain most of the fossils found in this part of the Nama Group. Carbonate beds become more common towards the top of this member, which is overlain by a thick carbonate unit of region extent (Mooifontein Member).

Southwards the basal clastics (Kanies Member) become thicker, while carbonate beds in the overlying Mara Member are more dominant. The Kliphoek Member becomes finer grained but includes some coarse grained clastics, and the Aar Member contains more and thicker carbonate beds. Paleocurrents show a dominant sediment transport towards the west and southwest.

Questions posed by the stratigraphy include whether the basin subsided at a constant rate, where was the shoreline at any given time, where were the input points of the clastic sediments and how and why did the influx rate vary? Did changes in sea level, and therefore shoreline position, influence the deposition of carbonates, or was this mostly influenced by a lack of clastic influx? We do not have accurate ages for the sediments or the rate at which they were deposited.

The Kalahari Manganese Field (KMF) of the Northern Cape Province of South Africa hosts about 74% of all known minable manganese ores globally. It represents the largest known land-based Mn deposit. More than 90% of the resource can be best described as mangano-lutite, e.g., a microcrystalline, ovoid-rich, finely laminated chemo-sedimentary rock containing between 30-40 wt.% Mn. Despite its great geological age (2.42 Ga), the mangano-lutite and its surrounding volcano-sedimentary host rock succession (Transvaal Supergroup) have not experienced any significant metamorphic overprint. Owing to its exceptionally fine-grain size and unusual composition, the mineral paragenesis and diagenetic microfabric of the mangano-lutites remain poorly documented. This contribution aims to show that modern SEM-EDS-based image analysis platforms, such as the TESCAN TIMA instrument, can not only provide quantitative mineralogical data, but can also reveal unprecedented insight into diagenetic microfabric and a complex succession of mineral assemblages in the mangano-lutites. The instrumental approach developed for this application is of extreme industrial and economic importance due to increasingly complex ores and a mandatory need to beneficiate by-products in the shift to sustainable mining. It can be easily transferred to other applications on fine-grained rocks (e.g. carbonate mudstones, fault gouges), ores (e.g. nickel laterites, bauxites) or anthropogenic solid materials (e.g. tailings, flue dusts).

Li extraction as a byproduct in deep geothermal power plants is a promising option for the upcoming challenges in Li supply chains. In Germany, regions in the North German Basin and Upper Rhine Valley are suitable for these kind of operations as Li concentrations reach up to 375 mg/l in deep formation waters [1]. To provide further insights on the occurrence of Li in deep formation waters, its geochemical behavior and possible release reactions of Li from mineral dissolution or surface exchange in deep geothermal systems, experiments at in situ conditions (100 – 160 °C, 370 bar) with drill core material of reservoirs rock were conducted in Au capsule and flexible Dickson-type Au-Ti cells. In addition, rock samples were investigated by petrographic and geochemical analysis in order to identify the main Li-bearing mineral phases and their respective Li concentrations. Results of fs-LA-ICP-MS measurements identified chlorite and biotite to be the main Li-bearing minerals, but low Li concentrations were also found in multiple other mineral phases. Batch experiments revealed that a near-equilibrium concentrations for Li are attained rapidly in 3 to 6 days of experimental run time.

[1] Alms, K., Jagert, F., Blömer, J., & Gehrke, I. (2022). Co-production of geothermal energy and lithium from geothermal waters. In European Congress.

Der Terminus „kritische Rohstoffe“ erlangte als Gegenstand der „Mitteilung der Kommission an das Europäische Parlament, den Rat, den Europäischen Wirtschafts- und Sozialausschuss und den Ausschuss der Regionen – Grundstoffmärkte und Rohstoffe: Herausforderungen und Lösungsansätze“ in Europa 2011 erstmals größere öffentliche Aufmerksamkeit.

Eine damals 14 Positionen umfassende Liste wurde seitdem mehrfach erweitert und umfasst derzeit 34 Rohstoffe. Ergänzend wurden im Jahr 2023 „strategische Rohstoffe“ definiert, welche zum größten Teil „kritische Rohstoffe“ beinhalten.

In diesem Vortrag wird der Frage nachgegangen, inwieweit die derzeit bekannten Rohstoffvorkommen Sachsens auch die von der EU definierten kritischen Rohstoffe beinhalten. Weiterhin werden exemplarisch ausgewählte Herausforderungen betrachtet, welche einen entscheidenden Faktor darstellen, ob derartige sächsische Vorkommen (z.B. von Cu, In, REE etc.) auch tatsächlich kurzfristig zur Sicherung der Rohstoffversorgung genutzt werden können.

Für die aktuell funktionierende ökonomische Basis Sachsens ist eine sichere Versorgung mit wesentlich mehr Rohstoffen erforderlich, als derzeit in Form der EU-Liste kritischer Rohstoffe im Fokus der Aufmerksamkeit stehen. Dazu gehören beispielsweise Baurohstoffe. Aber auch die stetige Erweiterung der als „kritisch“ definierten Rohstoffe lässt es sinnvoll erscheinen, für eine langfristige Sicherung der Rohstoffbasis weit vorausschauende Planungen vorzunehmen und nicht zu warten, bis ein Rohstoff offiziell als kritisch erklärt wird. Demgemäß sollten auch derzeit noch als unkritisch betrachtete Rohstoffe bereits jetzt vorsorgend erkundet und zumindest planerisch für eine eventuelle spätere bergbauliche Gewinnung gesichert werden.

Parallel zu diesen Bemühungen gewinnt die Beantwortung der Frage an Aktualität, inwieweit das derzeit prognostizierte weitere Wachstum des Bedarfes an Primärrohstoffen mit einer nachhaltigen Existenz des globalen Ökosystems Erde vereinbar ist.

The Sora Ni-Cu-(PGE) sulfide mineralization is associated with a ~400 x 40 m dike-shaped gabbroic intrusion that is exposed in a dimension stone quarry about 5 km SW of Bautzen (Saxony/Germany). The Sora dike is one of several Ni-Cu-(PGE) sulfide-bearing gabbroic intrusions (e.g. Angstberg, Dahrener Berg, Sohland-Rožany, Kunratice) that occur in the Lausitz and Šluknov region on both sides of the German-Czech border. The gabbroic intrusions are part of interconnected magmatic plumbing systems that intruded Cadomian granodiorites of the Lausitz Block (northern Bohemian Massif) in the Middle to Late Devonian (~390–370 Ma). The Sora dike represents a composite intrusion with olivine gabbronorite, gabbro and diorite as major lithologies. The magmatic sulfide mineralization comprises blebby disseminated sulfides in the olivine gabbronorite and variable-shaped massive sulfide patches that locally occur along both contacts of the gabbroic dike to the granodioritic country rock. Subordinately, larger sulfide patches are also hosted by pegmatitic albite-amphibole-enriched schlieren within the olivine gabbronoritic part of the intrusion. The mineralization represents a typical magmatic sulfide mineral paragenesis with dominating pyrrhotite, pentlandite and chalcopyrite, variable amounts of Fe-Ti oxides and trace amounts of PGE-, Au-, Ag- and TABS-bearing minerals. The PGE mineral assemblage is dominated by Pd melonite. The magmatic sulfides are characterized by relatively high Ni tenors (metal content in 100 % sulfide) and variable Cu, Co, Pt, Pd and Au tenors (~0.3–9.0 wt.% Ni, ~0.2–7.0 wt.% Cu, ~0.1–0.4 wt.% Co, ~20–1210 ppb Pt, ~40–1400 ppb Pd and ~20–1230 ppb Au).

The eastern part of the Erzgebirge region hosts an exceptional abundance of greisen- and vein-hosted Li-Sn-(W) deposits (e.g., the Zinnwald-Cínovec district), located across the eastern part of Germany and the northwestern part of Czech Republic. However, only a few of those deposits have been reliably age-dated (e.g., the Sadisdorf district), leaving the timing of hydrothermal mineralization on the regional scale widely unconstrained.

Here, we report new U-Pb LA-ICP-MS ages of cassiterite from Li-Sn-(W) mineralization at Zinnwald, Altenberg, Niederpöbel, Schmiedeberg, Bärenfels, Lauenstein and Krupka. The new ages of the different localities span between 315.1±3.7/4.4 and 306.6±1.5/3.5 Ma. Therefore, greisen- and vein-hosted cassiterite ages constrain hydrothermal mineralization's timing, on a regional scale, to a narrow time window of ~10 Ma years and are significantly younger than previously proposed ages between 325 and 318 Ma. The new ages are consistent with recent zircon ages of (sub-)volcanic rhyolite units (315 to 313 Ma), which are the host rocks of some of the Li-Sn-(W) granites. Greisen formation and associated cassiterite crystallization thus temporally coincides with the formation of the 315-310 Ma ring dykes linked to the collapse of the Altenberg-Teplice caldera.

The Erzgebirge hosts numerous stratiform tin occurrences, which are located along the same structural level within the Variscan orogenic belt. One of these tin deposits, the Bockau tin occurrence, is located in the area between Aue-Bad Schlema – Bockau – Zschorlau with alternating sequences of quartzite and metaschist. This layered sequence records geochemical signatures of intensely weathered sedimentary rocks. Their protolith probably formed during the Ordovician at the passive continental margin of Gondwana. The mineral assemblage consists of quartz + biotite + garnet + muscovite + andalusite + chlorite + cassiterite + accessory-phases. Cassiterite grains are concentrated in layers concordant to the foliation plane, occur as inclusions within foliation parallel biotite, and are overgrown by garnet blasts. These textures indicate that cassiterite has been present prior to the Variscan continental collision. The frequent occurrence of cassiterite also correlates with the high Sn-contents of the tin bearing metasediments (mainly ranging from < 50 to 2000 ppm). Different methods of conventional thermobarometry and pseudosection modelling were applied to reconstruct the regional metamorphic overprint at 550 ± 50 °C / 8 - 9 kbar and a subsequent thermal peak of at least 600 °C. These results are characteristic for the regional metamorphic conditions reached along the north-western border of the Erzgebirge, though the maximum temperatures reached are slightly higher than previously thought. There is a lack of evidence for a post-magmatic / metasomatic history of the Bockau tin occurrence by the applied methods and petrographic observations.

Several trace metals have gained societal and economic importance due to their limited and uncertain supply as well as their crucial role in high-tech applications, including various enabling technologies. These Technology-Critical Elements (TCE) are now recognized in the critical raw materials lists that are regularly published by entities such as the European Union and the United States Geological Survey. Notable examples are the rare earth elements, the platinum group elements, antimony, gallium, germanium and scandium.

In natural waters and soil solutions, many of these metals are found, due to their strong particle-reactivity, only in extremely minute concentrations, ranging from ng kg^-1 to pg kg^-1. However, their booming application in diverse technologies leads to a strongly increasing input from anthropogenic sources into the environment. At the same time, we face considerable knowledge gaps in their mobility, reactivity and bioavailability. The various chemical forms in which these metals are employed further complicate sound predictions on the mobility and bioavailability of these emerging contaminants in the environment. In this contribution, I will summarize the state of the art and challenges in constraining natural background concentrations as well as anthropogenic contaminations and will showcase research on their mobility, reactivity and bioavailability, with a special emphasis on the potential relevance of natural biomolecules (metallophores) for TCE mobilization and a potential rehabilitation. Such ligands are naturally produced by a range of microorganisms, plants and fungi to cope with the scarcity of nutrient metals, but may also actively promote the mobilization of TCE in the environment.

The ever-increasing application of rare earth elements and yttrium (REY) in diverse sectors has led to their emergence as environmental contaminants. In this study of the Oder and Vistula rivers in Poland, total concentrations of REY (ƩREY) in the dissolved phase (0.2 µm-filtered water samples) decrease from the river’s upper reaches (98.1 and 139 ng/kg) to mid-sections (52.4 and 48.4 ng/kg) but rise again near the estuaries (65.1 and 61.4 ng/kg). The upper reaches exhibit high levels of REY due to the impacts of high population density, strong industrial activity, and the input of acid mine drainage. The rise at their lower reaches indicates input from additional sources, possibly from phosphogypsum tailings. The Gd anomalies (Gd_SN/Gd_SN^*: 4.92 - 44.6) found at the studied sites reveal various Polish regions as hotspots of anthropogenic Gd microcontamination (where >95% of Gd is of anthropogenic origin), resulting in a significant flux into the Baltic Sea. Ultrafiltrates show HREY enrichment over LREY in the truly dissolved REY pool (<1 kDa), enhancing the trend seen in the dissolved phase as LREY preferentially associate with nanoparticles and colloids (NPCs: 0.2 µm - 1 kDa). The anthropogenic Gd is related to MRI contrast agents released with the effluents of wastewater treatment plants, displays negligible particle-reactivity, and resides almost exclusively in the truly dissolved REY fraction. Our results underscore the urgency of monitoring and understanding the anthropogenic impacts causing elevated REY levels and positive Gd anomalies in the Oder and Vistula rivers to protect the environment.

The reactivity and fate of Technology Critical Elements (TCEs) in rivers are still widely unknown. We present yearly monitoring results for Rare Earth Elements (REEs) and less known TCEs such as tellurium (Te) and Thallium (Tl), for three contrasting German watersheds: the Rhine, the Neckar and the Danube rivers. Monthly samples of water (0.45 vs 0.02 µm) and suspended particulate matter were analysed directly and after digestions via ICP-MS (iCAP series, Thermo®). Results show contrasting behavior between watersheds. For instance, only the Neckar River shows increased downstream transport of REEYs in the dissolved phase, reflecting the impact of dams along its course. In contrast, only the Danube River shows a mixed signal between geogenic and anthropogenic Gd, the latter disappearing completely during flood conditions. In any case, flood conditions enhance an overall transport of REEs in the truly dissolved phase for all rivers, increasing the amount released into the system, decreasing the log Kd values and causing a characteristic Tm negative anomaly. The opposite occurs for Tl and anthropogenic Gd, suggesting for Tl an anthropogenically dominated regime, especially at the Neckar and Danube rivers. All this information provides insights for developing scenarios for potential risk assessment of current and future anthropogenic releases of TCEs in aquatic environments.

Acknowledgements: This work was funded as part of the Excellence Strategy of the German Federal and State Governments. The authors also acknowledge the extensive contribution of LUBW (Germany) and AUE (Switzerland) for the collection of water and suspended sediment samples.

Rare Earth Elements and Yttrium (REY) are considered Technology-Critical Elements and contaminants of emerging concern due to their wide application but limited supply. The growing use of REY poses an environmental threat due to increasing entry into natural surface waters and the food web. Therefore, it is crucial to better understand speciation and complexation of REY under a wide variety of natural surface water conditions. Saline-alkaline lakes are present on all continents, cover up to 20 % of the area of all lakes worldwide¹ and up to 75 % in the East African Rift². Here we report REY from (saline) alkaline lakes and hotsprings from the Kenyan part of the East African Rift. The samples are characterized by alkaline pH values ranging between 7.24 and 9.91, which increases with increasing electrical conductivity as well as high DOC in lake waters (up to ~98 mg/L). Shale-normalized REY patterns show typical features of alkaline lake waters such as strong HREY enrichment over LREY. Preliminary inorganic speciation modelling suggests that carbonate is the dominant inorganic ligand. However, the alkaline rift valley lakes do not show the positive Ce anomaly that was previously reported for other alkaline lakes. The high DOC content of the lake waters (i.e. low molecular weight organic matter) might suppress typical Ce redox behavior. In marked contrast, alkaline hotsprings show similarly strong HREY over LREY enrichments, but positive Ce anomalies.

¹Wurtsbaugh et al. (2017) Nat. Geosci. 10 (11), 816.

²Butturini et al. (2020) Water Research, 173

The potential mobility and availability of trace elements in sediments/soils is commonly assessed via selective extractions. In this work, three contrasting sediments, i.e., Rhine riverbank sediment, alkaline volcanic heavy mineral sand, and mine tailings from a Mississippi-valley type ore deposit, are extracted with an oxalate-based solution and compared in terms of trace element mobility from both amorphous and crystalline Fe-Mn-carrier phases. Major and trace elements are characterized in the supernatants via ICP-OES and (HG-)ICP-MS, whereas the residual material is characterized via XRD. The obtained Fe/Si and Mn/As ratios highlight distinct sediment behavior over time. Overall, our results show a significant kinetic component, increasing concentrations for some elements like Fe, Mn, Ti, Si, Al, Mg, Sr, Na, Ge, Sc, and HREE (for the black sand), and decreasing for Ca, K, Y, REE after reaching supersaturation, e.g., formation of a characteristic whitish precipitate. Even though the protocol was successful at destroying most of the Fe-Mn(-Ti) minerals, the crystallization and sedimentation of oxalate salts may be due to the absence of stabilizing agents in solution. A similar situation occurs in the case of urolithiasis, where supersaturation of calcium oxalate in the kidneys, if not inhibited, promotes precipitation. Thus, the findings of this study not only highlight the environmental mobility of technologically critical elements in aquatic systems, but also their potential retention/accumulation in kidney stones.

Acknowledgements:

This work was funded as part of the Excellence Strategy of the German Federal and State Governments.

Rare earth elements (REEs), a group of elements with similar physical properties and coherent geochemical behaviour, are widely used as proxies for many biogeochemical processes. Interpretation of REE data is primarily based on distribution patterns in normalised graphs. Therefore, missing REEs can alter the appearance of the REE patterns and, consequently, the interpretation. Data for certain REEs may be missing for various reasons, e.g., they could not be measured (neutron activation analysis, isotope dilution techniques), the measurement was near to or below the limits of quantification or certain REEs were used as spikes. To address this, we introduce a novel method that leverages REEs' characteristically smooth distribution patterns to reconstruct missing REE data. Our approach provides accurate and precise REE data (<10% deviation) well within common analytical uncertainties of modern analytical techniques (e.g., ICP-MS). The accuracy and precision were determined using a method verification dataset of >13,000 mafic and ultramafic rock samples. The re-modelled REE data can be used to interpret the overall pattern and to quantitatively determine anomalies, one of the most important tools in REE research. Furthermore, our method offers new opportunities for REE data handling and processing, enabling researchers to assess the usability and reliability of REE data, whether self-produced or data from journal publications and data repositories. We implemented our method into our software tool GeoArmadillo, which facilitates geochemical data processing, evaluation and assessment.

Geothermal heat flow (GHF) is essential for evaluating the thermal states and energy balances of the lithosphere, playing a crucial role in geophysics and geothermal energy research. In this study, we initiate our analysis by exploring lateral variations in unknown thermal parameters across Germany. We apply a Bayesian Markov Chain Monte Carlo approach, using established data on surface heat flow, surface temperatures, and the temperatures and thicknesses at the lithosphere-asthenosphere boundary. Our investigation focuses on assessing the lateral variations in crustal and lithospheric mantle thermal conductivities, crustal heat production, and mantle heat flow.

To address the limitations posed by the sparse and uneven distribution of direct borehole data, which consists of only 595 heat flow points, our study integrates a broad spectrum of geophysical and geological datasets. These include gravity, magnetics, seismic data, topography, proximity to faults, and volcanoes, and compositional data within a machine-learning framework. This comprehensive approach not only surpasses traditional Curie depth estimations in accuracy but also robustly tackles the issue of data scarcity.

We employ quantile regression forests to clustering to integrate the datasets in a geothermal heat flow model. This probabilistic, multi-geophysical inversion method leads to a detailed quantification of uncertainties, offering a refined understanding of Germany’s geothermal potential.

Extracting heat from medium-deep hydrothermal reservoirs for municipal heat supply requires adequate reservoir characteristics, suitable extraction techniques, a sufficiently high heat demand and appropriate heat supply infrastructure. Furthermore, the acceptance of local stakeholders and consumers, as well as financial feasibility are crucial factors for the successful implementation of geothermal heat projects.

In the North German Basin (NDB) in particular, there are several deep geothermal projects that have been planned over the years but have never been completed, mostly due to the high exploration and financial risks at the beginning of the project. Some municipalities have already taken the initiative to restart projects.

The aim of this work is to provide technical support for local stakeholders to enable them to initiate and successfully implement hydrothermal projects.

In a first step, the authors identify aborted geothermal projects in NDB located in geologically well explored regions. Based on related feasibility studies, literature reviews and expert interviews, common constraints and challenges are discussed from geological, technical, social and economic perspectives.

Secondly, a number of selected projects are analysed in more detail. Alternative operating scenarios are developed and the positive impact of new technological developments such as high capacity heat pumps is examined.

Finally, the results will be generalised in order to derive recommendations for interested local stakeholders.

The work is part of the Warm-Up project, funded by the Federal Ministry for Economic Affairs and Climate Action (BMWK).

Geothermie spielt eine entscheidende Rolle für eine klimaneutrale Wärmeversorgung, jedoch sind bisher nur wenige Tiefengeothermie-Projekte in Niedersachsen umgesetzt worden. Das Norddeutsche Becken (NDB) beherbergt potenziell vielversprechende mitteltiefe geothermische Reservoire, insbesondere in den Kalkareniten der Reitbrooker Schichten des oberen Maastrichts. Diese wurden durch zahlreiche Bohrungen der Kohlenwasserstoff-Industrie erkundet und gelegentlich für die Abwasserentsorgung genutzt, was auf eine gute Gesteinsdurchlässigkeit hinweist. Spezifische Untersuchungen zu ihrer geothermischen Eignung fehlen jedoch bisher.

Bohrlochdaten und 3D-Seismik wurden analysiert, um das Reservoir zu kartieren und charakterisieren. Dabei wurden die Bohrungen über zwei mergelige Bereiche korreliert, welche die Arenite in obere und untere Bereiche unterteilen. Es wurde festgestellt, dass sich die Arenite der Reitbrooker Schichten lateral von Nord nach Süd zunehmend mit glaukonitreichem silikatischem Sand vermischen. Die aus Plug-Messungen von Kernproben gemessene Porosität und Permeabilität, kombiniert mit den berechneten Porositäten aus Sonic- und Density-Logs, lassen darauf schließen, dass tendenziell bei stratigraphisch höheren Arenite bessere Reservoirparameter zu erwarten sind. Die Verbreitung und Erhaltung der Arenite unterhalb des Paläozäns stehen im Zusammenhang mit der tektonischen Entwicklung, insbesondere der Inversion des Niedersächsischen Beckens. Große Mächtigkeitsschwankungen im Verbreitungsgebiet werden durch Halokinese verursacht, wobei besonders mächtige Ablagerungen in den Randsenken auftreten, während sie teilweise auf den Salzstöcken fehlen.

Das Zusammenspiel von Tektonik, Halokinese und Sedimentationsdynamik führt zu einem heterogenen Reservoir, das dennoch gut vorhergesagt werden kann. Zur Bewertung des geothermischen Potenzials, zur Kartierung und zur Entwicklung von Erschließungsstrategien sollen noch numerische Simulationen durchgeführt werden.

The geothermal heat anomaly in northern Bavaria was first discovered in the late 1970s and has recently been more precisely localized. An elevated temperature of 57 °C estimated at a depth of 1000 m is estimated to be higher than that based on the normal geothermal gradient. The geothermal gradient is approximately 4.5 °C/100 m with a heat flow density of 110 - 130 mW/m². The location and extent of the geothermal anomaly are constrained by the limited number of deep wells, which has left the cause of the positive heat anomaly in the region enigmatic. In this study, we use geophysical methods and modeling to locate the granitic intrusion in the subsurface as a possible source of the observed high geothermal anomaly.

An important feature of the northern Bavarian subsurface is the presence of granitic intrusions covered by early Carboniferous turbidites and Permian graben and half-graben structures (Rotliegend sandstone), similar to those exposed setting in the western Bohemian Massif. By integrating the geological and geophysical data and modeling, we define the location and geometry of a granitic intrusion and estimate the depth to basement. Our 2D forward models predict the structural and stratigraphic setting satisfying observed geological and geophysical data. Our integrated methodology describes the granitic intrusion, the sedimentary cover, and the regional structural patterns relevant to ongoing deep geothermal exploration. This study contributes to subsurface characterization (e.g. potential reservoir and buried fault zones) and reduces risks associated with exploration and potential future development.

The Bavarian part of the North Alpine Foreland Basin (NAFB) is highly relevant for geothermal exploration, especially amid recent play developments, highlighting the importance of an integrative geological and geophysical approach. Our work focuses on establishing a robust seismostratigraphic framework for the Bavarian NAFB using an unprecedented dataset consisting of digitised (vintage) seismic and well log data.

Based on this unique data set, we interpreted and correlated well logs and identified important seismic reflectors across the NAFB using seismic-to-well ties and synthetic seismograms, refining seismostratigraphic concepts from previous models such as GeoMol [GeoMol Team – Project Report (2015)]. Our study incorporates considerations of different depositional facies, focusing on the continuous traceability of major reflectors throughout the basin. We identified five major Tertiary reflectors that can be consistently tracked across various lithological and facial boundaries and follow major basin-wide unconformities. Especially the main reflectors identified within the complex Egerian successions and their ability to be traced across different lithostratigraphic units (i.e. Lower Freshwater/Brackish/Marine Molasse), serve as an example of how the reflectors are partially independent from stratigraphic boundaries and their varying facies distributions. Instead, the presence of major seismic reflectors in the NAFB is rather determined by basin-wide unconformities, whose distinctive seismic signatures serve as a basis for consistent identification across the basin.

Our work provides a fundamental step towards an integrated seismostratigraphic framework for the Bavarian NAFB, aiming for a coherent approach of seismic interpretation in industry, academia and authorities, thus promoting standardized methodologies for future (geothermal) well development.

The fit for 55 package, which outlines policy measures to deliver the EU Green Deal, calls for a greater than 40 % target for renewable energy sources by 2030 in the Renewable Energy Directive (RED). It also calls for an increased primary (39 %) and final (36 %) energy savings to be achieved by the Energy Efficiency Directive (EED). Accelerating the penetration of cost-effective and energy efficient renewable heating and cooling (RES HC) technologies will be key to the successful achievement of these targets.

Geothermal heat pumps are the most cost-effective and efficient source of renewable heating and cooling on the market. They can meet the heating and cooling needs in residential and non-residential buildings of all sizes with varied energy profiles. Furthermore, they can be applied as individual applications at building scale, or through renewable district heating and cooling systems.

One big challenge at the moment and for future years is decarbonising heating and cooling grids for new builds and in particular for existing buildings. geoENERGIE Konzept presents projects in different stages of development of their wide portfolio. Hereby lies the focus on district heating and cooling grids for new as well as existing buildings, hybrid systems with other renewable sources and underground thermal energy storage.

On geological timescales, Earth’s climate is closely linked to the silicate weathering feedback through the coupled silica-carbon cycles. Weathering of silicate minerals on land sequesters atmospheric CO₂. This process is counteracted by marine authigenic clay formation (also known as reverse weathering), which consumes alkalinity and releases the beforehand sequestered CO₂ back into the ocean and atmosphere. Despite the significance and first description already decades ago, the balance between the terrestrial and marine silicate weathering feedback remains difficult to quantify and is mainly attempted indirectly via elemental and isotopic shifts in fluid composition.

In this talk, I will give an overview of controlling processes on silicate weathering from the Archean to the present day, with special emphasis on the close coupling of the terrestrial and marine weathering regimes. I will show, how silicon isotopes (δ³⁰Si) and Ge/Si ratios can be used to decipher weathering and reverse weathering processes and how early diagenesis impacts originally-inherited signatures, hampering the interpretation of authigenic clay geochemistry in the geological record. As an outlook, I will discuss the approach of enhanced silicate weathering in the marine environment as a tool to mitigate climate change through ocean alkalinisation.

Quantitative paleotemperature estimates from the Precambrian are rare due to the scarcity of well-preserved sediments and uncertainties about the isotope composition of ancient oceans. Carbonate triple oxygen isotope measurements (δ¹⁸O and ∆’¹⁷O), however, can be used to overcome these challenges and estimate climate conditions in deep time.

In this study, we investigated interglacial carbonates from the Cryogenian Oodnaminta Reef Complex in Australia, deposited between the Sturtian and Marinoan Snowball Earth events. According to petrological and sedimentary analyses, dolomitization of originally aragonitic reef components occurred immediately after deposition, along with the precipitation of primary dolomite cements.

Our dolomite data display a negative trend in triple oxygen isotope space that cannot be explained by diagenesis, yet it can be attributed to precipitation from a single fluid at various temperatures. To be able to calculate carbonate precipitation temperatures, we first modelled the oxygen isotope composition of the seawater. Initially, we simulated a range of conceivable seawater compositions using an extended oxygen mass balance model. Subsequently, from the modelled values, we selected those compositions that best fit our samples. The resulting seawaters exhibit δ¹⁸O values of around -5‰ and ∆’¹⁷O values of around -10 ppm. Such seawater compositions are feasible when considering the fluxes of silicification and carbonatization. Finally, we derived seawater temperatures of 10 °C to 50 °C, indicative of a temperate Cryogenian interglacial climate.

The Cenozoic cooling that occurred over the past 50 Ma is accompanied by an increase of Mg/Ca in seawater. How this change in seawater chemistry is linked to climate change is still disputed. Mg isotope ratios of seawater could distinguish several possible causes including dolomitization, authigenic clay formation and changes in rates of silicate- and carbonate weathering. Previous reconstructions of Mg isotope ratios of paleo-seawater were based on foraminifera, corals or carbonate muds, which however yielded conflicting results. Here we assess the suitability of bivalves from genus Glycymeris as archives for paleo-seawater δ²⁶Mg (the standardized ²⁶Mg/²⁴Mg). Their potential advantage over other archives arises from their strong evolutionary conservatism, thick shells and a fossil record dating back to the Lower Cretaceous. We established a new method to analyze δ²⁶Mg for samples with a very low Mg/Ca ratio. We report Mg isotope signatures from ventral margins of shells of three recent Glycymeris species from the Adriatic Sea that show an increasing fractionation with increasing ontogenetic age. Similar isotope signatures were observed across single shells, a property that we are going to exploit in the future for reconstructions of paleo-seawater δ²⁶Mg from specimens of fossil Glycymeris.

The energy transition will require vast amounts of mineral raw materials. Only a small part of this demand is likely to be covered by recycling. A large part of the current discussion has therefore centered on the question whether the mining industry can provide sufficient supply in this critical period of global development. This lecture briefly examines the magnitude of this issue, and then discusses current research aiming to improve our foresight on future mineral supply. The examples of gallium and lithium will be used to illustrate the most important questions as well as potential solutions.

The Werra Potash District is located on the border of the federal states of Thuringia and Hesse. Mining has taken place in this area for more than 125 years. The mined area is larger than the city of Munich. The two potash seams in this area, called the Thuringia and Hesse Potash Seams, are generally between 3 and 5 meters thick and are located in the Werra Salt, which is 300 m thick. There are two active mines, Hattorf-Wintershall and Unterbreizbach, in which approximately 19 million tonnes of raw salt are mined annually. Exploration is very important for mining in terms of being able to forecast and obtain information about the thickness and mineralogy of the potash seams, the presence of basalt dikes and areas with hydrogeological risks or gas hazard areas.

In general, exploration can be divided into two categories: surface exploration and underground exploration.

Surface exploration: there are many surface drill holes and shafts from the last century that allow conclusions to be drawn about the geology and mineralogy of the potash seams and the overburden.

In addition, numerous geophysical measurements are carried out like seismic surveying, gravimetric surveying and geomagnetic measurements.

Underground exploration: in the two active mines, underground drilling with a length of more than 80 km per year is carried out. All underground drill holes are measured using 3D radar. All geological data are processed in a 3D geological model, which enables forecasts for mine planning, resource estimation as well as geomechanical modeling.

In-mine seismics provide a better resolution and spatial coverage than surface exploration methods such as 2D or 3D seismics, enhancing the exploration around underground facilities. Over the past decades, seismic exploration techniques have been developed to address challenges in exploring ahead and around tunnels and mines. Methods such as reflection seismics and tomography are applied, taking into account the constraints on resolution and exploration range due to the distribution, accessibility, and shape of in-ground cavities.

The major challenges for the application of underground seismic exploration include avoiding cost-intensive downtimes of construction and production, as well as minimizing risks to underground facilities for safety reasons. The Integrated Seismic Imaging System (ISIS) largely integrates seismic exploration into the workflow of tunnel construction. ISIS has been improved to 3D underground seismics within the Helmholtz Innovation Lab 3D-Underground Seismics. For a detailed seismic exploration, seismic sources and receivers are used in all accessible underground spaces. The exploration capabilities were enhanced with a seismic borehole tool for exploration ahead, a borehole receiver chain, and a borehole source in exploration boreholes.

With efficient impact hammers or magnetostrictive vibrators as sources and three-component receivers, our 3D underground seismics can resolve and image 3D structures in underground with reconnaissance depths up to several hundred meters and resolutions of dm to m. Especially for exploration in clay-bearing salt reservoirs 3D underground seismics is an alternative to the established GPR. We present the components of our 3D-underground seismics and discuss their applications based on case studies in various salt mines.

We explore this question using the example of salt structures in Northern Germany. The salt mines in the North German basin are among the best explored in the world. The question now arises as to whether findings on the internal structure of these salt structures also allow conclusions to be drawn about previously unexplored diapirs. BGR worked on the crucial question posed by BGE on the prediction of homogeneous salt volumes in saline rocks. However, improvements in the prognosis could also support the exploration and possible future economic use (as storage caverns) of underexplored salt structures, for example in the German North Sea. Our method is based on the definition of several basin-wide assessable proxies, which suggest an influence on the internal structure and its variability with regard to the utilization of the salt structure. Furthermore, additional findings on genesis, kinematics or the detailed internal structure are discussed which cannot be directly transferred into a basin-wide proxy but can contribute to the evaluation of the variability of the internal structure. Due to the wide range of influencing factors to be discussed, our presentation will focus in particular on new findings on salt tectonics from the comparison of the analyzed structures, but also on the given limitations of a prediction of the internal structure. In summary, certain types of salt structures that have passed through certain evolutionary stages indicate a higher probability of larger salt homogeneous volumes in economically exploitable depths.

Rock salt is a valuable commodity for the food and fertiliser industries. It is also used as a host for artificial underground structures, such as caverns. As part of Germany's transition to net-zero energy by 2045, rock salt caverns will continue to be needed, but they must be suitable for storing green hydrogen. Salt deposits could also provide a potential source of lithium, with German demand currently being met by imports. However, more information is required to understand the potential of rock salt deposits and to decipher their suitability.

Several stratigraphic salt horizons occur in the geological record of Schleswig-Holstein, ranging in age from the Triassic (Keuper, Muschelkalk, Bunter) to the Permian (Zechstein, Rotliegend). The economically exploited horizons are of Zechstein and Rotliegend ages and often form salt domes and walls. A special feature is the so-called "Doppelsalinare", where older Rotliegend salt is intruded into younger Zechstein salt due to rheological processes.

The aim of this study was to characterise the different salt horizons in terms of their mineralogy and geochemistry and to identify any potential lithium resources. To achieve this, rock salt samples were examined by polarised microscopy, quantitative mineralogy was determined by X-ray diffraction, while geochemistry was analysed by X-ray fluorescence and inductively coupled plasma mass spectrometry.

Our results show that each stratigraphic salt horizon is characterised by a unique Br-Cl spectrum, with lithium and other trace elements also showing distinct patterns.

Two significant potash-bearing basins occur within Central Asia. The Pricaspian Basin refers to an approximately 600 km wide (east-west) structure at the northern end of the Caspian Sea. This structure is filled with up to 4.5 km thick Permian (Kungurian and Roadian (Kazanian)) evaporite rocks and covered mainly by clastic sediments. Due to the large thickness of overlying sediments, diapirism of the salt rocks started with an initial movement phase between the late Permian and the Triassic and a later movement phase in the period between the Juraissic to the Neogene. Several hundreds of salt structure, that bring the potash salt close to the surface are known within the basin.

The Central Asian Salt Basin is a Jurassic to Early Cretaceous evaporite basin that spans across Uzbekistan, Turkmenistan, Tajikistan and Afghanistan. Occurrences of potash salts are largely confined to the Late Jurassic Gaurdak Formation, though evaporites of Paleogene age are also known. The deposition of the salt deposit is connected to the development of the Neotethys. Maximum thickness of the Gaurdak Formation is about 1,200 m with the evaporites being thickest in the vicinity of the Gissar Range. Clastic and carbonatic sedimentary rocks make up the hanging wall of the formation. The basin was divided by uplift of the Gissar range in Miocene times into the Amu Darya Basin towards the west and the Afghan-Tajik Basin to the east. Salt rocks are present at or close to the surface around the Gissar range.

Often, geological models are generated based on information obtained from exploration data, e.g. borehole records. These borehole records contain descriptions and interpretations about petrography (lithology) and stratigraphy, respectively. The information is crucial for modeling the spatial distribution of lithostratigraphic layers. However, the interpretation of the drilling profiles is error-prone as it depends on several factors, including date of recording, exploration target, quality of digitalization of the borehole record and the human interpretation bias of the responsible expert, among others. Due to the large number of boreholes drilled during explorations, separating adequate from insufficient drilling profiles is of great importance, yet rather difficult. While visual inspection of the inferred geological model is a viable approach it results in numerous iterations to filter inadequate drilling profiles which is time-consuming and expensive.

We present a Python-based software package that predicts the quality of lithostratrigraphic data from borehole records based on several criteria. Using pre-checked reference drilling profiles, we train a random forest model to predict the quality of non-checked drilling profiles for geologically comparable regions. The aforementioned selection criteria as well as the predictors are individually definable by the software user.

As a study area, we selected a former lignite mining area of Lusatia bordering the Federal State of Brandenburg and the Free State of Sachsen (Saxony). Here, 71 pre-checked and classified drilling profiles exist which are combined with erroneous synthetic profiles and used to train the random forest model to predict the quality of the >3000 remaining profiles.

Until now, the BGR’s geological general map series of different scales were not connected to each other in terms of data technology. Accordingly, the GK1000 (Geological Map of the Federal Republic of Germany 1:1,000,000) was previously generated manually from the GÜK250 / GÜK200 (The General Geological Map of the Federal Republic of Germany 1:250,000 / 1:200,000). Within the framework of the AGNES (Automated generalisation/derivation of geological spatial data) project, the generalisation tool “AutoGen” of the State Office for Geology, Raw Materials and Mining in Baden-Württemberg (LGRB) has been adapted using the above-mentioned two general maps, so that a largely automated derivation of small-scale spatial data from large-scale spatial data is possible. The talk will give an overview of the results of the AGNES project and the tool “AutoGen” as well as an outlook on further work in the future.

3D information systems are becoming increasingly important in Hesse (Lehné et al. 2017). The pilot study “Darmstadt_3D”, which delivers urban subsurface data, including technical infrastructure, is highly utilizes by the user community of the city of Darmstadt, the HLNUG and the TUDa. Based on these project experiences, a further project was initiated in 2020 for a small working area in northern Hesse, southeast of Kassel (Lewin et al. 2021). Meanwhile, the working area, geologically located in the Hessian depression, has been expanded to cover the entire city area, spanning approximately 240km².

The database of the structural geological 3D model consists of 9535 quality-checked drillings, several of which have also been used to construct 50 cross sections that help to better elaborate the fault network and layer dip. Additionally, four geological maps (GK25) were harmonized, and nine already existing cross sections were incorporated. The 3D modelling is performed using SKUA-GOCAD and includes the base of the stratigraphic horizons Quaternary, Tertiary, as well as the lower Triassic formations Röt, Solling and Hardegsen. Difficulties arise from varying data densities and conflicting input data.

Initial results reveal a complex tectonic situation, primarily characterized by the WNW-ESE trending graben system of Kassel. Displacement rates of stratigraphic horizons can exceed 100m.

To archive a fully integrated urban 3D-information system for Kassel, the structural geological 3D model will be parameterized (e.g. hydraulic conductivities, radon potentials) and published via GST.

Started as a project at a geoscientific hackathon in 2018 and released to the public in 2020, GST[AR] is an app-based attempt of utilizing Augmented Reality (AR) to bring 3D geological data to almost everyone with a smartphone or tablet. In this way, multiple european-based geological surveys already offer some of their models to experts and interested users alike today. 3D subsurface models especially are great for public engagement and education as they are easier to grasp and fun to interact with. GST[AR] joined the growing list of tools that allow users to visualize geological data without the need for expensive and proprietary software, but chose to do it with the rather novel technology of AR.

AR holds great potential since it is a fun and intuitive way to interact with 3D data and is readily available on most portable devices. Enabling users to directly manipulate a 3D scene is essential for user engagement, but also for gaining a deeper understanding of the spatial relations and dimensions. Simpler methods like creating an animation, or still image, of a 3D model fall short in that regard because they lack the interactive component. In this presentation we will look into the capabilities of the app, ways for everyone to utilize their own models, and the potential this holds for conferences and education.

Scientific drilling is a well-established tool in Earth sciences and related disciplines. For drilling on land, the International Continental Scientific Drilling Program, ICDP is the major player providing implemental funding and technical support. The largest number of ICDP projects aim at drivers of Paleoenvironmental and Paleoclimate evolution with a focus on dramatical and rapid changes. While Quaternary archives such as lacustrine sediments still predominate, more and more Mesozoic to Paleozoic time slices of dramatic System Earth transformations come into the play. Even Precambrian times are on the agenda such as Neoproterozoic Snowball Earth, Early Precambrian oxygenation of the atmosphere, or Early Earth origin and evolution of life.

Another key topic in the ICDP are Geohazards including mainly seismic and volcanic risk and research on landslides or a combination of cascading disastrous events. First approaches in this field of science were often related to the feasibility of drilling in fault zones or active volcanic regions while current ideas focus on monitoring and testing.

Energy-related scientific drilling projects on e.g., geothermal challenges and other critical resources often acquire funding from national governmental resources. In contrast, fundamental basic research questions are usually developed as bottom-up international academic initiatives. In order to bridge the gap between these two advance lines in geothermal research, ICDP has now established new funding priorities including not only ‘World-Class Science’ and ‘World-Class Sites` but also ‘World-Class Opportunities’.

This contribution will summarize current trends and initiatives in terms scientific objectives and will elucidate funding challenges as well as chances.

To define parameters for future climate change scenarios (IPCC) and their consequences for ecosystems, it is of paramount importance to improve our knowledge of timing, duration, and intensity of past climatic variability and subsequent environmental impact, especially on long geologic time scales and in key regions such as the Tibetan Plateau. Considering that the Tibetan Plateau serves as the source of several major rivers the future hydrological development will clearly have a significant societal impact. Nam Co is one of the largest and deepest lakes on the Tibetan Plateau. Due to this location at the intersection of Monsoon (increased precipitation) and Westerlies (increased evaporation) paleoclimate proxies derived from sediments of Nam Co clearly reflect the spatial and temporal interplay and thus the dominance of one of the two circulation systems.

Seismic data show that the Nam Co basin contains >800 m of well layered undisturbed sediments. Sediment accumulation rates measured on a 10.4 m reference core, seismostratigraphic investigations, and molecular clock analyses suggest an age of the seismically imaged sequence of >1 Mio years. Instead of drilling the entire >800 m sediment sequence in the center of the lake we will use the fact that layers are dipping towards the center of Nam Co producing a higher accumulation rate there. By splicing together multiple cores from three different sites it will be possible to cover the same depositional history found at >800 m in the center, i.e., 1 Ma.

Fossil deep-sea macrobenthos is scarce due to the rarity of onshore deep-sea sediments. Therefore, hypothesized migrations of shallow shelf taxa into the deep-sea after phases of mass extinction or oceanic anoxic events (onshore-offshore pattern) is not constrained by the fossil record. To resolve this conundrum, we investigated 1,475 deep-sea sediment samples (Atlantic, Pacific, Southern oceans; 200 - 4,700 m paleo-water depth). Ca. 41,500 spine fragments from Holasteroida and Spatangoida (Atelostomata) document a continuous occurrence of the groups since 104 Ma (late early Cretaceous). Literature records suggest even an older age (115 Ma). A gradual increase of spine tip morphotypes occurs since the Albian. An abrupt reduction in spine size and morphological inventory following the Cretaceous-Paleogene (K-Pg) Boundary Event is expression of a “Lilliput Effect”, related to nourishment depletion in the deep-sea. The post-event recovery lasted at least 5 Ma. Post-K-Pg Boundary Event assemblages seem to evolve progressively without any morphological breaks towards modern deep-sea assemblages. This observation is interpreted to result from in-situ evolution in the deep-sea and not from onshore-offshore migrations. The calculation of the “atelostomate spine accumulation rate” (ASAR) reveals low pre-Campanian values, possibly related to high remineralization rates of organic matter in the water column in the course of the mid-Cretaceous Thermal Maximum and its aftermath. A Maastrichtian cooling pulse marks the irreversible onset of fluctuating but generally higher atelostomate biomass that persists in the Cenozoic.

Between 5.97-5.33 Ma, kilometre-thick evaporites were deposited in the Mediterranean Basin during the Messinian Salinity Crisis (MSC) under strongly negative hydrological budget. In the light of the IMMAGE initiative to drill the Mediterranean-Atlantic gateway, we present here the reconstructed continental mean annual temperatures (MAT) using branched glycerol dialkyl glycerol tetraether (brGDGT) biomarkers for the MSC Stage 3 (5.55-5.33 Ma) and compare them with continental temperature values obtained from Δ₄₇ clumped isotope geochemistry of paleosol carbonate nodules from few Mediterranean locations. The biomarkers were extracted from outcrops onshore and offshore sites around the Mediterranean Basin. Calculated MATs for the 5.55 to 5.33 Ma interval show values around 16 to 19 ºC for the Malaga, Sicily and Cyprus outcrops. The MAT values for DSDP Leg 13 holes 124, 134 and Leg 42A holes 374 and 376 are lower, around 13 to 16 ºC. Comparing the brGDGT-MAT values with Δ₄₇-MAT values from carbonate nodules, shows high congruence between both approaches. For the northern Mediterranean Δ₄₇-MAT is 24.6 ± 1.6 °C and brGDGT-MAT is 19 ± 4.8 ºC. For Cyprus Δ₄₇-MAT is 20.3 ± 1.7 °C and brGDGT-MAT is 18 ºC ± 4.8 ºC. Given the very different nature of the used paleoproxies, the similarity of the obtained MAT values provides a strong indication of (cross)validity in sampled sections. Additionally, the measured δ¹⁸O for the carbonate nodules used for the Δ₄₇-MAT show high δ¹⁸O of the soil water (~ -5 ±0.7‰) indicating highly evaporative conditions for the two onland Northern Apennines and Cyprus locations.

Shallow weathering patterns and linked hydrostratigraphy in topographic recharge areas are rarely explored even for used groundwater flow systems, as (scientific core) drilling was usually carried out in downstream zones of productive resources. In the Hainich Critical Zone Exploratory (NW Thuringia, Germany), we constructed a well network encompassing the recharge area (hilltop, midslope) in discharge direction (footslope) for long-term monitoring of the links between surface and subsurface biogeosphere (Küsel et al., 2016). In total, ~730 m of rock cores from the limestone-mudstone alternations of the Upper Muschelkalk, including drillings in the thick hillslope aeration zone, were used for the exploration of hydrogeological functions, flow paths and endolithic habitats (Kohlhepp et al. 2017). Based on the core and monitoring data, an advanced conceptual model on multidirectional flow patterns and subsurface ecosystem compartmentalization was developed (Lehmann and Totsche, 2020). Novel and surprising findings revealed unseen patterns in the Upper Muschelkalk flow system: confined weathering phenomena in fissures and pores indicate localized, oxic conditions in sections that were previously encountered elsewhere as anoxic and unweathered. This indicates a higher complexity of flow and transport pathways (e.g., oxygen supply) than commonly expected, despite simple layer-cake geometry of the bedrocks. Besides relief position, it points to a strong influence of fractures on flow in the aeration zone.

References: Kohlhepp et al. (2017): https://doi.org/10.5194/hess-21-6091-2017; Küsel et al. (2016): https://doi.org/10.3389/feart.2016.00032; Lehmann and Totsche (2020): https://doi.org/10.1016/j.jhydrol.2019.124291

A specialized workflow incorporating two innovative computing algorithms has been developed to understand and quantify natural hydrogen generation through the serpentinization of ultramafic rocks. This approach integrates geological, geophysical, structural, and petrophysical parameters. The area is divided into three critical zones: Surface, Shallow, and Deep. The Surface layer provides insights into hydrogen presence and migration paths. Detailed exploration of the reservoir and its seal is enabled by the Shallow layer, while the Deep layer focuses on the mechanisms behind hydrogen formation. Semi-circular structures indicative of natural hydrogen are detected by the NHSD (Natural Hydrogen Seeps Detection) algorithm, which applies deep learning to satellite imagery. In the Shallow layer, the reservoir seal is assessed using geological and geophysical modeling, which also examines the presence of fractures that act as migration paths. In the Deep layer, models employing gravity and magnetic data inversion, together with temperature distributions in a 3D model, target conditions favorable for serpentinization. The QNHG (Quantifying Natural Hydrogen Generation) algorithm calculates daily hydrogen production by scaling laboratory experiments to field conditions. This algorithm considers factors such as production rates, water/rock ratios, serpentinization front velocity, temperature, and fracture systems in peridotites—all adjusted to the characteristics of the study area. This refined system offers a comprehensive method for characterizing natural hydrogen environments, adaptable to various geological settings.

Hydrogen is regarded as an important part of our future emission free energy mix. Naturally occurring hydrogen could be a good candidate for the pursued energy mix as it does not need to be produced in an energy-intensive way. Many hydrogen seeps have been studied to characterise the concentrations and fluxes of the emanations and link these to the underlying rocks. Different multi-disciplinary methods are necessary to characterize the different aspects of a hydrogen generation system. However, further research into the hydrogen production potential of various rocks and settings is necessary. In our study, we applied numerical modelling to a 2D cross section in northern Bavaria (Münchberger Masse, Münchberg Massif) and integrated our current geological knowledge on the formation of the Münchberg Massif as well as literature data and own new measurements on rock samples. Based on the collected data we calculated several scenarios of hydrogen formation and transport during the geological evolution of the area and for the present day situation using the software TerrantaLab & TerrantaFlow. Possible hydrogen-generating rocks are the serpentinites and orthogneisses of the Münchberg Massif. Carboniferous granites of the Fichtelgebirge, which outcrop adjacent to the Münchberg Massif, could also generate hydrogen at greater depths. We present several scenarios of hydrogen formation to gain a better understanding of the decisive processes for natural hydrogen generation in the study area.

Hydrogen is expected to become a keystone of the energy transition to reach climate neutrality. In the future hydrogen economy, underground hydrogen storage (UHS) will become an integral part of the European hydrogen infrastructure.

The German hydrogen demand is expected to increase from 2030 on and a hydrogen storage demand of ca. 10% of the annual hydrogen demand is estimated. To meet this storage demand, existing storage capacity needs to be converted and new capacity installed. While current natural gas storage is mainly seasonal, hydrogen storage needs to be more dynamic to meet a growing hydrogen demand on the one hand and a fluctuating supply of green hydrogen on the other hand.

Next to operational challenges, underground hydrogen storage in salt caverns and porous reservoirs also faces several research challenges.Geochemical and microbiological processes in geological formations and their impact on hydrogen quality, storage integrity and reservoir performance are some of the main R&D demands for the safe implementation of UHS.

The BGR project "Generation, Migration and Degradation of Hydrogen – BiMiAb-H2" was developed to enable a quantitative investigation of the influence of geochemical and microbial processes on reservoir performance and caprock integrity.

This paper provides an overview of expectations and potentials for UHS in Germany and current research at BGR to address some of the remaining research questions.

To enable large-scale underground hydrogen storage, porous rock formations can complement the storage space of salt caverns, which currently are investigated in first pilot tests in Germany. In porous rocks, mainly sandstone formations, several reactions and processes might impart on the storage of H₂.

Here we present first data for five formations with an in depth petrographical and mineralogical characterization as well as experimental investigations with high partial pressures of H₂ under near in situ pressure-temperature-conditions. The formations investigated include Tertiary sandstones (Bunte Niederrödern Schichten, Chatt), Tertiary limestone (Lithothamnienkalk), the Triassic Solling Sandstone and the Permian Wustrow and Schneverdingen Sandstone. For each formation, small diameter core plugs and thin sections were prepared from core samples for petrophysical and petrographic characterisation. One part of each core section has been crushed and milled, the pulverized rock material analysed for mineralogical and geochemical composition. In addition, the rock material was investigated in high-pressure experiments and the consumption of hydrogen quantified over a duration of 2 to 4 weeks. Overall, the hydrogen oxidation by H₂-fluid-mineral surface reactions is limited; several mineralogical factors responsible for the oxidation are evident. Additional experiments investigating the kinetics of individual reactions, e.g. of iron oxides present in the rock material, complement the first assessment of geochemical reactions in these possible storage formations.

Underground hydrogen storage (UHS) in geological reservoirs is proposed as a technically feasible solution to balance mismatch between supply and demand in emerging markets. However, unique hydrogen properties and coupled flow mechanisms require new investigations to fully understand transport and storage of hydrogen in porous media across scales. Here we use microfluidics to investigate the effect of gas type and injection rate on flow patterns, saturation and connectivity of the gas phase. We visually observe that gas flow is characterized by capillary fingering, further confirmed by fractal dimension analysis. At lower injection rates, the gas saturation after drainage appears to increase with gas viscosity, with lower hydrogen saturation compared to methane and nitrogen. The maximum gas saturations (39–46 %) were achieved at higher injection rates, showing no clear correlation to gas type. However, the high-rate injections lead to undesired outcomes in terms of formation of disconnected gas ganglia, mostly pronounced for nitrogen. We identify an optimal injection rate to achieve maximum gas saturation with the least amount of disconnected gas.

Exploration for buried mineralised pegmatites is challenging because of their lack of distinctive geophysical signatures. The GREENPEG project (project GA869274, EU HORIZON 2020 programme) has developed a multi-method toolset based on an improved understanding of pegmatite properties, settings and genesis.

The Leinster pegmatite belt is located within the narrow (<3 km) but extensive, SW-NE trending East Carlow Deformation Zone (ECDZ) which forms the eastern contact of the late-Caledonian composite Leinster Batholith that intruded previously deformed Lower Palaeozoic metavolcano-sedimentary rocks. The unexposed spodumene pegmatites form up to 20 m thick NW-dipping sheets.

Shear zones/faults, and lithological boundaries can be delineated using airborne geophysics on a province and district scale. At prospect scale, the ECDZ is clearly visible in electrical resistivity tomography (ERT) measurements that also allow the identification of weathered granite, faults, and high resistivity areas prospective for pegmatites.

Lithium concentrations in soils and certain minerals in stream sediments (spodumene, garnet, kaolinite) provide successful pathfinders for subcropping pegmatites.

Orientation data for different structures, obtained from borehole logging combined with field and drill core observations, enabled the identification of several generations of (barren) pegmatite and indicate a relatively late emplacement age for the spodumene pegmatites. This is consistent with quartz from the spodumene pegmatites having lower Ti and higher Al, Li, and Ge concentrations than that in barren pegmatites, indicating more evolved compositions.

We show that complementary geophysical, geochemical, and geological methods can be successfully used for spodumene pegmatite exploration. The data furthermore enhanced our understanding of pegmatite emplacement in SE Leinster.

Exploration for buried pegmatites presents a challenge, mainly caused by weak geophysical signals due to commonly low petrophysical contrasts between pegmatites and wall rocks. However, dedicated petrophysical studies and a better genetic, structural, and lithologic understanding of pegmatites motivate reassessment of the geophysical methods pool and open the door for refined pegmatite exploration workflows. The EU Horizon 2020 GREENPEG project developed a toolset for this purpose, including a comprehensive petrophysical database for European pegmatites, that is both cost-effective and promotes sustainable exploration, while combining geophysical and geochemical exploration methods.

The Jennyhaugen quarry close to Drag, Northern Norway, hosts N(iobium)-Y(ttrium)-F(lourine) pegmatites and served as one of the field labs for the development of the exploration toolset. We present here insights gained during comprehensive field tests for method selection and combinations, while we focus on the geophysical exploration tools.

NYF pegmatites often have a geochemical halo enriched in the radioelements thorium, uranium and potassium, highlighting gamma-ray spectrometry as a successful tool to be used in areas with no or little soil cover. When targeting hidden pegmatites, depth penetrating methods like ground penetrating radar and electrical resistivity tomography, in combination with legacy drill core lithology, ground magnetics, gravity and innovative piezoelectric sensing proved in part very successful. The combination of the individual methods closes interpretation gaps and besides identifying buried pegmatites, we also improved understanding of the settings and geometries of pegmatites.

As an innovation in the EU-funded H-2020 GREENPEG project (GA 869274), the Geological Survey of Norway (NGU) has developed a state-of-the-art piezoelectric seismograph (PES) as a valuable contribution to pegmatite exploration. The instrument utilizes the piezoelectric effect which describes the conversion of mechanical pressure into electrical energy, or vice versa. This technology has been leveraged to detect quartz, for gold exploration since the 1970s. NGU applied newest electrotechnology and data processing to customize it for granitic pegmatite exploration. The pilot was deployed in different settings e.g. at the GREENPEG demonstration sites in Tysfjord/Drag pegmatite field, Norway, where the pegmatite occurs in the Tysfjord granitic gneiss intrusion as lens-shaped bodies. The pegmatite mainly consists of feldspar, plagioclase, biotite, and a quartz core with dominant accessory minerals of Niobium, Yttrium and Fluorine (NYF). The survey detected buried quartz deposits at a depth of 5–10 m, using 100g minimal invasive explosive charges. The results were confirmed by drill cores. At another site in Tysfjord/Håkonhals the quartz was found at even 15–25 m depth embedded in the host rocks amphibolite and gneiss, using an 80 kg drop-weight with minimal environmental impact.

Since this novel piezoelectric seismograph is exclusively sensitive to the presence of quartz, it has a lower ambiguity compared to other geophysical methods applied in pegmatite exploration and is a sustainable and cost-efficient method for pegmatite exploration, both as a stand-alone method and in combination with other methods on brownfields and greenfields.

LCT pegmatites are the main solid rock resource for battery lithium with a market share of over 50%. The focus of current and future exploration and mining beyond the current main supplier Australia is emerging in southern Africa and Canada. Europe will only be able to cover a good quarter of its own requirements if the currently explored deposits are all mined. Non-European LCT pegmatites are therefore becoming increasingly important. The EC is therefore striving for raw materials partnerships ie with Namibia. But Europe is not alone here. China in particular has become active in several African countries, both entrepreneurially and politically. Investments by private Chinese companies have exceeded the financial resources provided by the EC for the development of raw materials partnerships many times over. Furthermore, European companies play a subordinate role, own mining operators are missing, as are take-offs or backward integration of European OEMs

More than this, Chinese companies are increasingly getting involved in or taking over exploration projects. However, the rush for lithium in Africa risks fueling corruption and failing citizens. The presentation provides an overview of the deposits and geopolitical ambitions of the main consumer states as well as the supplier countries in the region under review and ventures a forecast for securing Europe's raw materials in global competition.

Geophysical measurement procedures are currently tested in the western Erzgebirge as part of the GeoMetEr project in order to optimize the surface exploration of potential nuclear waste repositories. The research area, which is strictly excluded from the site search, features a deep fault zone in the crystalline basement, the so-called "Roter Kamm". The fault is explored using a combination of seismic, magnetic and electromagnetic methods, and the results are later verified by a 2 km deep research well. Additionally, existing geological and geophysical data, mainly from the historic uranium mining, as well as new data collected during the project will be integrated into a consistent 3D subsurface model. The complex structures in the crystalline rock, which resulted from the multi-phase development of the Erzgebirge, thereby pose considerable challenges. Consequently, the classical modelling procedures, which were rather developed for sedimentary environments, have to be adapted. Here, we present the first results of the structural modelling in the research region. Special attention was given to representing major fault zones, which are assumed to be the primary fluid pathways in the basement. Furthermore, model uncertainties are investigated for selected elements using a self-developed SKUA-GOCAD macro that enables the automatic generation of multiple model realizations.

Attributed 3D volumetric models are important tools for planning resource exploration, subsurface storage of natural gases and waste and for risk management. Of particular interest are subsurface temperatures and lithological attributes, which reveal important evidence on geothermal potential, characteristics of deep aquifers and reservoir rocks and support project planning.

A harmonized 3D structural model of the entire North German Basin was prepared in the scope of the project "Potentials of the underground storage and economic area in the North German Basin" (TUNB). The current second project phase is focused on parameterizing this model with various petrophysical and geological parameters. Here, we present our approaches and results for modeling subsurface temperatures, lithologies and clay contents in the area of Northern Saxony-Anhalt.

Temperature gradients from borehole logs were applied to model formations and adjusted to the thicknesses of the highly thermally conductive Zechstein formation for calculating subsurface temperatures. Lithological information were derived from a comprehensive lithologic-paleogeographic map series. Shale fractions were qualitatively estimated from petrographic descriptions and quantitatively confirmed using gamma ray logs. Subsequently, a fault seal analysis was performed based on clay contents and the lithofacies model. The results demonstrate the numerous possibilities for large-scale parametrization with discrete and continuous parameters and form the basis for comprehensive information systems and databases for further project planning and prospection efforts.

In Lower Saxony, the base Quaternary shows a diverse relief, largely due to the complex network of buried tunnel valleys, which are primarily associated with the Elsterian glacial stage. They cut into underlying Tertiary sediments. Incision depths range from a few tens of meters to 400 meters. The tunnel valleys may host minable sand and gravel deposits and groundwater reservoirs. They can help to predict the erosion depth of future glaciations, which is an important constraint for the storage of radioactive waste. Thus, a comprehensive up-to-date geological 3D model of the base Quaternary is crucial to support strategies in sustainable resource extraction and land use.

The new Lower Saxony 3D model is compiled in SKUA-GOCAD™ (AspenTech) and is based on a broad dataset. The existing contour map of the base Quaternary is combined with more recent data, e.g. regional 3D models and extensive borehole data. The use of seismic data (2D/3D) has been particularly effective for mapping tunnel valleys as it enables a spatially inclusive representation of these structures. In the current model region (northwest Lower Saxony), several previously unknown tunnel valleys were discovered, reaching depths of up to -200 m NHN. The depth of known subglacial channels was adjusted up to 250 m compared to the previous contour map. Following the completion of the first sub-region, we anticipate that the base Quaternary will reveal significantly deeper tunnel valleys in the new 3D model across the majority of Lower Saxony.

The existing 3D subsurface model of Mecklenburg-Western Pomerania covering the northeastern part of the North German Basin was developed in depth domain between 2014 and 2020. It comprises the major lithostratigraphic boundaries from the base of Rupelian clay down to the base of Zechstein and the regional fault network (Obst et al. 2024).

A complementary model in time domain and a consistent velocity model of the same area are currently constructed in the framework of the project TUNB Velo 2.0. The model in time domain is based on 2D-seismic surveys from the 1960s to the 1980s that are now combined, re-interpreted and harmonized in a regional 3D approach. The velocity data (from check-shots, vertical seismic profiles and vintage velocity models from local to regional scale scale) are aggregated and harmonized to a consistent and seamless 3D-velocity field in a country-wide scale that is used for depth-time- and time-depth-conversions. The GOCAD/SKUA software (AspenTech) is used for all models.

The new models will provide new interpretations and processing data for a more substantial view of the geological subsurface in depth and time domain in order to support future investigation campaigns and developments.

References:

Obst, K., Brandes, J., Matting, S., Wojatschke, J. & Deutschmann, A. (2024): Das 3D-Untergrundmodell des Landes Mecklenburg-Vorpommern: Datengrundlagen, Modellierungsergebnisse und Anwendungsmöglichkeiten.- SDGG (in print).

Over the past 150 years, the Lusatia region has transformed into a landscape heavily influenced by lignite mining. The newly proposed regional " Groundwater Model - Lusatia " (GWM-L) is initiated to become a pivotal tool for cross-border groundwater management in Saxony and Brandenburg, addressing complex post-mining water management issues.

The primary objective is to establish a robust hydrogeological structural model that accurately delineates aquifer stratigraphy and lithology. This foundational model will subsequently support the integration of soil water balance models with groundwater flow models under changing climatic conditions.

Developing GWM-L entails significant challenges, including uncertainties in geological structures and material parameters, integrating extensive existing data, and balancing computational efficiency with model realism. Despite established methodologies, the model's complexity demands a meticulous, stepwise approach using advanced modeling techniques. Various local hydrogeological models from mining operators at different sites will be correlated to maximize data utility and accuracy.

The structural model must accurately depict geological conditions down to 350 meters. The LBGR sets the target for Brandenburg at the reference horizon (base of the Rupel Formation layers). This contribution will delineate the fundamental processes of geological data acquisition, highlight inherent data heterogeneity, and present advanced methodologies employed to construct a comprehensive digital, three-dimensional hydrogeological structural model. The resulting model will enhance our understanding of the Lusatia region’s hydrogeology and provide a critical foundation for sustainable groundwater management amid ongoing environmental and anthropogenic changes.

For Lower Saxony, the model TUNB3D-NI consists of 13 lithostratigraphic units from Zechstein to Tertiary in the North German Basin. Furthermore, it includes salt domes and major fault systems. In the project TUNB Velo 2.0, the 3D structural model will be transformed in a 3D volume model and parameterised with reasonable seismic velocities. The resulting model enables to convert information on a regional scale from time to depth domain and vice versa.

Currently, we are working in a pilot region in the eastern part of Lower Saxony. Data from previous regional velocity studies (Jaritz, 1991), borehole measurements and seismic velocity analysis serve as the input for velocity interpolation and quality control. In Aspen SKUA, the regional velocity model is build with two different modelling approaches: A voxet is created with regions defined by the lithostratigraphic units. Within the regions, the velocities are assigned based on a depth dependent formula with the “Apply Script” command. For the second approach, the velocities in depth are generated with EPOS` SeisEarth module. After import in Aspen SKUA, we used the “Structure & Stratigraphy” workflow to generate the 3D volume model. It is parameterised with the “Reservoir Properties” workflow afterwards.

On the poster, we will provide insights in the modelling process, compare both methods and show the resulting velocity model.

References:

Jaritz W., Best G., Hildebrand G., Jürgens U. (1991) Regionale Analyse der seismischen Geschwindigkeiten in Nordwestdeutschland. Geol Jahrb 45:23–57

The Geological Survey of Schleswig-Holstein is project partner in the joint project TUNB Velo 2.0. This R&D project aims to develop large-scale velocity models for the Northwestern German Basin based on all velocity data available.

Previous models rely on borehole velocity data (mainly check shot data) only. However, such measurements are sparsely available throughout the entire modeling region, thus emphasizing the need for additional data types. Velocities obtained during seismic processing, particularly stacking velocities, are originally provided by the oil and gas industry alongside with the corresponding seismic sections. These seismic velocity data are much more widely distributed across Schleswig-Holstein and Hamburg than the borehole data and therefore cover the modeling region to a much larger extent. Furthermore, partly available raw data allow us to conduct our own seismic reprocessing including a velocity analysis.

In our study, we discuss the integration of processing velocities into the regional velocity models by performing our own seismic velocity analyses at specific locations. We thereby derive confidence intervals for velocities. Near check shot measurements, we evaluate the relationship between check shot and processing velocities with regard to a future calibration of both data types.

In times of increasing demand for mineral resources, the collaborative project DESMEX-REAL aims to combine geophysical data from newly developed semi-airborne electromagnetic (sAEM) measurement systems with geological data from centuries of mining in the Upper Harz Mountains. This data is available from borehole files and exploration reports about drilling, geochemical and geophysical analyses of the former Preussag AG and the federal drilling program in the Western Harz Mountains in the 1980s. The geological maps and a limited number of geological cross sections are further input data for the geological model.

In a first step, all available information was collected, quality controlled and visualized in a GIS project. Selected data was then used to build a conceptual model for the project area in the Upper Harz Mountains, using the 1:200 000 geological map sheet 4726 Goslar. The faults on this map have been processed and adjusted to the vein map of the Upper Harz Mountains. The trend of the faults, the exposure of the geological horizons at the surface, and the boreholes including the geological markers were imported into the 3D modelling software Aspen SKUA™. The next step of fault modelling took into account the dip and dip direction of the faults. The geological horizons are subsequently modelled by using the information from borehole data, geological maps and cross sections. Modelling of the electrical conductivity structure using 3D inversion of sAEM data reveals conductivity anomalies along some geological faults at former mining veins and beyond.

Brandenburg contributes to a transnational 3D-velocity model of the North German Basin. This 3D velocity model is embedded in the framework of TUNB velo 2.0 where the State Geological Surveys of Mecklenburg-Western Pomerania, Schleswig-Holstein, Saxony-Anhalt, Lower Saxony and Brandenburg as well as the Federal Institute for Geosciences and Natural Resources (BGR) jointly work on a seamless velocity model. Brandenburg contributes as an associated partner. TUNB velo 2.0 not only focusses on the parameterization of the 3D model but also on comparing methodologies as well as the harmonization at state borders to achieve a seamless and transnational model of the North German Basin.

The geological model of Brandenburg covers Cenozoic, Mesozoic horizons and also includes the Paleozoic Zechstein group. Horizons are based on the results of the predecessor project TUNB which resulted in a 3D geological model of the North German Basin. A voxel model is derived from the TUNB horizons within a pre-defined pilot area and parameterized with seismic velocities. The resulting voxel model has a resolution of 50 x 50 x 25 m.

In Brandenburg, the parameterization is based on data of the late 1970s. Due to the GDR's efforts to achieve self-sufficiency, hydrocarbons were increasingly explored in the 1960s to 1980s – mainly with 2D seismic surveys. Local scaled velocity models were continuously updated using vertical seismic profiles, check shots as well as stacking and migration velocities. The last coherent speed model was created in 1977 and was supplemented in the following years by further small-scale velocity models.

The Bückeberg Group in the Lower Saxony Basin, northern Germany, records the transition from a lowstand systems tract to a transgressive systems tract during the Berriasium. The terrestrial to nearshore deposits of the Bückeberg Group comprise sandstone- and mudstone-dominated intervals. These sandstone-dominated intervals act aspotential geothermal reservoirs[GvG1] , especially where sandstone exceeds porosities and permeabilities of 30% and 500 mD, respectively. However, the sedimentological and ichnological character of reservoir facies, and their vertical and lateral distribution are complex and a sequence stratigraphic framework has yet to be established.

Facies and facies associations are identified by logging a set of 12 cores that bear terrestrial and nearshore deposits. Facies descriptions focus on sediment texture, sedimentary structures, lithological accessories, bioturbation index (BI), bioturbation distribution, and trace fossil assemblage. Vertical juxtaposition of facies associations are identified to delineate sequence stratigraphic surfaces. Three reservoir facies are identified and interpreted as (1) brackish-water, wave- and river-dominated deltaic deposits, (2) spit and barrier deposits, (3) fluvial channel and crevasse splay deposits. Several small-scale base level fluctuations took place during the overall transgression resulting in a complex distribution of reservoir facies.

The sedimentological and ichnological facies analysis of the Bückeberg Group permits refined reconstructions of its paleodepositional environments. Establishing a sequence stratigraphic framework offers valuable insight into the onset of Early Cretaceous transgression in the Lower Saxony Basin and enhances reservoir quality predictions.

Granitoid complexes have gained increasing importance and scientific interest. They play a significant role as a repository for highly radioactive waste and in the exploration of deep geothermal potential. Geochemical variations, grain size differences and age are well suited for classifying granites; however also influence their rheological and petro-physical properties. A detailed understanding of these properties is necessary to draw conclusions about the thermal and hydraulic behavior.

A number of granite intrusions characterizes the Mid-German Crystalline Zone (MGCZ) and the Saxo-Thuringian Zone (STZ). These syn- to post-variscan magmatites are part of a complex arrangement with low- to high-grade metamorphic rocks. With approximately 20 “different” intrusive bodies, the classification of the Thuringian granitic rocks suggests a broad variety. Zircon crystallization ages range between 340 Ma and 280 Ma (e.g. Zeh et al. 2005; Thieme et al. 2023). However, there is no correlation of these intrusion ages and the intrusion bodies recognizable.

Whole-rock geochemical classification of the granitoids of the MGCZ and the STZ includes the analysis of 80 samples. To visualize differences and to identify similar chemical signatures, multidimensional scaling and clustering of the Kolmogorov-Smirnov similarities was applied.

The optimal number of clusters resulted in six geochemical types for the MGCZ and five for the STZ. These correlate with the petrological-structural description of the samples. Almost all geochemical types occur in almost all "different" intrusive bodies. Considering the crystallization ages with regard to the petrological-structural-geochemical results, the granitic rocks of the MGCZ and STZ indicates successive intrusions.

The Heller fan (“Heller Sande”) is located on the eastern slope of the Elbe Valley north of Dresden and belongs to a series of coalescing alluvial fans that cover the eastern slope of the Elbe Valley. The fans run parallel to the Lusatian Thrust, which forms part of the Elbe Fault Zone. The origin and age of these alluvial fan deposits have been controversial for many years.
They overly Cretaceous shallow-marine sandstones and/or Middle Pleistocene Saalian glaciolacustrine deposits, which were deposited into the large ice-dammed Elbe Lake. To get insight into the timing of alluvial-fan deposition luminescence dating was applied to 18 samples collected from the Heller fan. Fan onset and aggradation occurred in response to climate change at the end of MIS 3. The major period of fan aggradation was between 33-18 ka. Involutions, isolated syngenetic ice-wedge casts and frost fissures indicate that temperatures were sufficiently cold to permit the development of ice wedges and point to periods with intense seasonal frost or permafrost conditions under persisting sediment aggradation. Rapid fan aggradation was followed by fan inactivity, abandonment and incision during the Lateglacial.
Post-Middle Pleistocene fault activity is indicated by the formation of disaggregation bands that cross-cut Middle Pleistocene Saalian glaciolacustrine deposits and show the same orientation as the Lusatian Thrust (Winsemann et al., 2022).

Winsemann, J., Hartmann, T., Lang. J., Fälber, R., Lauer, T. (2022): Depositional architecture and aggradation rates of sandrich, supercritical alluvial fans: control by autogenic processes or high-frequency climatic osciallations? Sedimentary Geology 440, 106238. https://doi.org/10.1016/j.sedgeo.2022.106238.

The Rotliegend is one of the most important target horizons for Oil and Gas production in the Netherlands as well as Lower Saxony. Therefore, these horizons have also been explored in the German North Sea, but the exploration often revealed either no gas potential or a high enrichment with N2. Despite this, good porosities and permeabilities of partially thick sandstones in the basal sequences of the Rotliegend were frequently found. Due to these factors and the very thick seal units of the Upper Rotliegend and the Zechstein, these sandstone sequences are becoming increasingly interesting for CO2 storage. Although the Rotliegend units have been of economic interest in recent decades, the German part of the North Sea has been underexplored in this regard, and very little has been published. Therefore, the BGR is re-investigating these storage and barrier formations on a regional scale based on wells and reflection seismic data, and will evaluate the static storage potential of this formation in the future. The mapping study presented here was carried out as part of the GEOMARE joint project GEOSTOR and in the context of BGR's long-term tasks defined by the national Carbon Dioxide Storage Act (KSpG). We present log correlation work, exemplary seismic interpretations, and discuss the uncertainties of our mapping study.

Available ages and pressure-temperature estimates of the rocks from the Ograzhden unit of the Serbo-Macedonian Massif (SMM) in Bulgaria indicate a Variscan ultra-high-pressure metamorphic event at ~334 Ma (Trapp et al., 2021, Terra Nova 33, 174-183). The bulk of the Ograzhden unit are Variscan migmatites. Cretaceous amphibolite-facies metamorphism and deformation were reported from the Vertiskos unit in the Greek part of the SMM (Kilias et al., 1999, Int. J. Earth Sci. 88, 513-531) whereas the Ograzhden unit is considered to be largely unaffected by Alpine orogeny (Kounov & Gerdjikov, 2024, Geologica Balcanica 53, 29-85).

We present new structural data from the Ograzhden unit collected along a profile through the Triassic Igralishte pluton, documenting that along with at least two Variscan high-grade deformation events a substantial Alpine upper greenschist to lower amphibolite-facies overprint is present in the Ograzhden unit. Alpine ductile deformation is inhomogeneous and localised along several high-strain shear zones. This is in line with interpretations that the Ograzhden unit, and the SMM in general, forms part of the high-grade Rhodope Metamorphic Complex, although the Ograzhden unit is situated within the hanging wall of the extensional system that exhumed the Rhodopes in the Late Eocene to Neogene time.

Greywackes represent a substantial part of the Cadomian basement of Saxo-Thuringia. The trigger for the widespread contact metamorphic, Cadomian overprinting of the greywackes investigated here, is assumed to have been caused by early Cambrian intrusions (c. 540 Ma; Linnemann 2007, Geol. Soc. London Spec. Publ., 286, 35–51). Here we present for the first time a multi-method approach, using electron microprobe U–Th–Pb analyses of monazites, K–Ar fine-fraction analyses and the illite crystallinity of suitable samples from the Lausitz Anticline and North Saxon Anticline to obtain information on the age and degree of metamorphic overprint. Petrographic investigations show that the studied greywackes have only experienced slight metamorphic overprint. The age dating did not detect a Cadomian influence (540–530 Ma). Rather, the ages are locally very different. In some of the samples, the data reveal multi-stage thermal events. Late Cambrian monazite ages could be associated with the transition from the Cadomian orogeny to the opening of the Rheic Ocean. Early Ordovician monazite and sporadic Late Ordovician monazite and K–Ar ages also occur. Their meaning regarding a thermal event is a matter of debate. Some K–Ar ages of c. 314–294 Ma and monazite age of c. 280 Ma are clearly associated with the processes of the high-temperature metamorphism and most probably, the post-tectonic granites of the Variscan orogeny. The youngest monazite age from the Jurassic in one of the samples could be related to the hydrothermal activity observed in Central Europe during that time.

Brittle deformation of continental lithosphere due to high strain rates is often associated with the abrupt failure of rocks and the release of seismic energy, which results in the occurrence of earthquakes. This process is associated with a rapid increase in frictional heat and can produce frictional melts that are instantly quenched to form pseudotachylites. Such structures help to understand the interplay between brittle deformation and hydrothermal and fault activity. This is particularly important with respect to nuclear waste disposal and production of deep geothermal eneregy.

We document pseudotachylites from the Mid-German Crystalline Zone, which is represented by the NW-SE trending Thüringer Wald basesment-high. It is composed of syn- and postvariscan, partially deformed crystalline rocks that are overlain by volcanic- and volcaniclastic rocks of the Rotliegend (Permian Redbeds). The Thüringer Wald is fault bound to the Mesozoic cover in the NE and SW and was uplifted during Mesozoic to Cenozoic times (e.g., Thieme et al., 2023).

Pseudotachylites were recovered in syn- to post-Variscan granitoids and successions of quartz-porphyric pyroclastic rocks of the Lower Rotliegend. Here, cataclastic zones host cm-sized black veins of glass-like material that crosscut the sample and carry cataclasts of host rock material. Inclination of the pseudotachylite veins is approx. 60°, which suggests that formation of the veins was associated with normal rather than reverse displacement. This could either represent direct evidence for post-variscan extension or volcanic activity related to Rotliegend-volcanism.

The Flechtingen Basement High (FBH) is one of the most striking basement uplifts formed due to the late Cretaceous contraction of Central Europe. It represents the separating element of two realms of Mesozoic strata deposited in the former Central European Basin, the Altmark region in the north and the Subhercynian Basin in the south. In its central part, which is our area of interest, the internal structure of the FBH comprises Paleozoic rocks of Carboniferous and Devonian age, which were deformed during the Variscan Orogeny. In Late Cretaceous times these rocks were uplifted in the backlimb of a large thrust-bounded basement anticline showing a continuous transition from Paleozoic to Mesozoic strata of the Subhercynian Basin in the south. In the eastern part additional backthrusts occur where Devonian strata is overthrust on Triassic sediments. Due to a thick Cenozoic cover investigating the structural style of these thrusts by means of classical geometrical modelling is hampered by missing detailed geological and geophysical data. Therefore, we use an integrated tectonic-geophysical modelling approach by combining classical tectonic concepts of cross-section balancing, 3D geological modeling and an in-detail analysis of gravity data including gradient calculations as well as Euler deconvolution to gain additional information on the fault network and hidden, deep-seated structures. First results show that this approach significantly enhances our understanding on the distribution of Permocarboniferous basins and on the dip and subsurface expression of large thrust faults.

In the Kreibitz-Zittau area at the northern margin of the Bohemian Massif (Czech-German border region), a ca. 1.000-m-thick Cenomanian to Mid-Coniacian succession of multi-recycled quartz arenites with high compositional but low textural maturity is exposed. In the northern Bohemian Cretaceous Basin, translucent heavy minerals (tHM) are nearly exclusively composed of zircon (Z), tourmaline (T) and rutile (R) with an average ZTR maturity index of 91. Tourmaline is most common and dominates the tHM spectrum with an average of 60 %. Zr-in-rutile temperatures document the upper amphibolite-eclogite to granulite facies with two peaks at 700–760°C and 800–930°C. Cr/Nb discrimination of rutile and Fe-Mg-Al geochemistry of tourmaline unambiguously indicate a more than 95 % dominance of Al-rich and Fe-Mg-poor metapelites. Garnet grains are scarce, but the majority belongs to the almandine-pyrope series. Pb/U-ages of detrital rutile show a distinct peak between ca. 320–330 Ma, less than 5 % have older ages of ca. 570–600 Ma. The 95 % predominance of Variscan ages in all Upper Cretaceous samples and the high temperatures of metamorphism excluded the Neoproterozoic greywackes and granitoids of the eastern Lusatian Massif as well as the granitoids of the Jizera–Krkonoše Massif in the north to northeast of the depositional area as supposed source. Parent rocks were abyssal low-pressure granulites in the high-grade metamorphic gneiss / migmatitic Góry Sowie Massif, ca. 100 km to the east of the depositional area, which was uplifted and eroded during Late Devonian / Early Carboniferous times (Aramowicz et al. 2006).

The Elbe Zone northeast of the Erzgebirge is an example of the complex architecture of Saxo-Thuringia of the Central European Variscides. Here, low grade lithologies of the Elbtalschiefergebirge preserve the record of Devonian to Early Carboniferous marine sedimentation, which occurred contemporaneously with prolonged subduction-accretion-exhumation tectonics of the Erzgebirge nappe pile. Today, both juxtaposed units are separated by the Mid-Saxon Fault Zone.

Based on tectonic field studies and microstructural investigations, we present a tectonic model for the Elbtalschiefergebirge as follows. As part of the SE-Wrench and Thrust Zone (WTZ), the lithologies of the Elbtalschiefergebirge originated at the passive continental margin of the Gondwana plate eventually affected by the Variscan orogeny. Until the Middle Devonian, the WTZ and the adjacent Autochthonous Domain share a similar geological record of a continuous sedimentation on the inner Peri-Gondwana shelf. Syn-collisional strike slip tectonics of the evolving WTZ started in the Late Devonian separating the Autochthonous Domain and the evolving nappe stack of the Allochthonous Domain northwest and southeast respectively. Differentiation of the WTZ begins with the onset of Late Devonian submarine magmatism and shallow to deep-water sedimentation. The deep-water sediments probably express the start of accretionary tectonics southwest of the Cadomian Lausitz block. Ongoing convergence in the Early Carboniferous resulted in nappe stacking and low-grade metamorphism. Early Carboniferous synorogenic sedimentation of Late Devonian cherts reveals ongoing accretion-exhumation tectonics at this part of the WTZ. Final (N)NW-(S)SE compression is related to the final juxtaposition with the Erzgebirge utilizing the Mid-Saxon Fault Zone.

The Western Polish Outer Carpathian Thrust-fold Belt is in comparison to the Eastern Polish Carpathians deprived in geologic and thermochronologic data, likely as its prospect potential has been considered limited; new efforts by both industry and academia my change this. We present first results of a study that aims for a new cross section that integrates prior and new seismic, borehole, field-mapping, structural, thermal, and thermochronologic data. Preliminary, we find that the onset of thrust-related exhumation in the Magura and Silesian nappes started in the Eocene. Two younger exhumation episodes may have occurred in the early and late Miocene. We did not find evidence for mid-late Miocene convergence-parallel (~N‒S) extension (extensional collapse of the Carpathian thrust stack) in the Western Polish Outer Carpathians, the possible dominant factor for the rejuvenation of apatite fission-track ages in the Eastern Polish Outer Carpathians. Two alternative scenarios may apply: the Miocene exhumation episode may result from (i) underplating of the Magura nappe by an antiformal stack of the Dukla nappe, (ii) tectonic denudation in the footwall of large-scale, seismically-proven normal faults that formed in response to the arc-parallel extension, (iii) a combination of both, acting more or less contemporaneously.

Key words: Carpathians, apatite-fission-track thermochronology, brittle fault tectonics

Middle–Upper Jurassic strata and ammonites from Iran are fairly well-known from the Alborz Mountains of northern Iran, the Koppeh-Dagh in northeast Iran and the thick successions on the Tabas and Lut blocks in Central Iran. However, very few data are available from the Talesh Mountains in northwest Iran where the condensed succession of the Shal Formation respresents the higher part of the Jurassic sequence. Thus, we conducted an integrated study of the Shal Formation in order to provide detailed biostratigraphic data, to characterize its depositional environment by means of (micro-)facies analysis and to place the succession in a geodynamic framework. The Shal Formation rests erosionally along the Mid-Cimmerian unconformity on siliciclastic strata of the Shemshak Group and consists of reddish, nodular bioclastic float- and packstones with abundant ammonites and filaments (rosso ammonitico facies). According to the ammonite faunas, deposition of the Shal Formation started in the upper Bajocian and continued into the early Berriasian. The ammonite association with common Lyto- and Phylloceratidae indicates offshore and deeper marine environments, supported by the rosso ammonitico-type facies that commonly characterizes condensed, current-swept deep-water environments. The deposition of the Shal Formation occurred on the southern rifted shelf of the South Caspian Basin (SCB) that experienced considerable extension and thermo-tectonic subsidence in the aftermath of the Mid-Cimmerian Event. Shallow-water deposition prevailed in the southwest (Lar Formation) while towards the northeast, into the SCB, the Shal Formation characterized condensed deep-water environments on submarine swells, potentially represented by crests of submerged fault blocks.

The Ixhuatlan de Madero area is located (in the geology of Mexico) between the Gulf of Mexico and the micro-continent Oaxaquia. The regional stratigraphy comprises the Paleocene Chicontepec Formation (chiefly sandstones and shales), overlying the Cretaceous Mendez and Tamaulipas formations, respectively composed of shales and limestones. Analysis of the structural data collected in the field indicates five stages of deformation. The first stage is characterized by upright folds plunging to the NE and SW. The second stage corresponds to the Laramide orogeny (i.e. ~ 40 Ma) and involves NE-vergent folds. The folding produced south-westwards shallow-dipping layers (i.e. less than 30°) and overturning of the first stage folds to the NE. The third stage is marked by reverse faults compatible with NE-SW compression as observed in the village of Cantollano. In contrast, NW-SE normal faults observed to the NW of Ixhuatlan reveal a fourth stage characterised by an extensional regime. The fifth stage involves NW-SE and NE-SW fractures present mainly west of Ixhuatlan de Madero. The latter fractures represent pronounced weakness zones within the rock mass and are further opened by plant roots and excavated by the tropical rains of the region. The control local disintegration of the rock and lead eventually to landslides. The landslides promote mass transport towards the NE and SW dominantly and, furthermore, the building of houses and human infrastructures amplify them.

Integrated stratigraphic-sedimentological analyses of numerous Lower Cenomanian–lowermost Turonian core sections from the Upper Cretaceous Elbtal Group, conducted in the framework of a multilateral research project initiated by the Saxon State-Office for Environment, Agriculture and Geology (LfULG), provide insight into the stratigraphic architecture of the fluvial to marine strata filling an asymmetrical palaeovalley. The project supports the scientific monitoring of the flooding process of the former Königstein uranium ore mine. Our sedimentological-stratigraphical study forms the basis for the hydro-geochemical sampling and analytical strategies of allied project partners.

The N–S-directed Königstein palaeovalley, cut into the basement of the Mid-European Island, borders the Saxonian Cretaceous Basin in the SW. Sedimentation closely followed contemporaneous sea-level changes, reflecting a continuous up-dip shift of facies belts. Northern and middle segments of the palaeovalley were filled with Lower Cenomanian siliciclastic fluvial deposits (Niederschöna Formation), while southern parts were still bypassed. Stratal architectures indicate a steep eastern and a shallower western palaeovalley margin. First marine influences (ichnofossils) are observed in the Middle Cenomanian Wurmsandstein of the upper Niederschöna Formation. The retrogradational facies development continued during the early Late Cenomanian when widespread, mature sandstones (Oberhäslich Formation) draped most of the pre-existing palaeo-topography. After the levelling of the pre-Cenomanian relief by the Niederschöna and Oberhäslich formations, the marine onlap was completed by the rapid plenus transgression and the deposition of the fine-grained offshore deposits of the uppermost Cenomanian Pennrich Formation, culminating in a maximum-flooding interval (Lohmgrund Horizon) at the base of the Lower Turonian Brießnitz Formation.

The remediation of the former uranium deposit site Königstein faces the problem to restore the groundwater level to its original state, because the uranium was leached with sulfuric acid from a Cenomanian paleovalley. For the management and monitoring of the groundwater level rise, a precise hydrogeological model is necessary. The former mine is situated in the facies transition from marine shelf sandstones (aquifers) interfingering with aquitards of pelitic units, deposited in a more distal environment. Sea-level changes controlled the depositional architecture. Detailed documentation and correlation of 39 cores urge for revising established lithostratigraphic concepts in the Elbsandsteingebirge area. The marginal sandstones of the Turonian Schmilka-, Postelwitz- and Schrammstein formations are very homogeneous. The correlation of the boreholes is therefore supported by the correlation of episodic major stormbeds. Both progradational and retrogradational patterns are observed in the clastic succession. Towards the northeastern source area, marl and clay units of the lamarcki- and labiatus- Pläner are reduced in thickness or pinch out completely. We observe a rapid switch between sandy and marly beds in the transition zones between the lithostratigraphic units, impeding lateral correlations with the sandstones, but allowing a sequence stratigraphic approach. Locally, a direct onlap of Turonian sediments on Paleozoic basement is observed, caused by the progressive sedimentary fill of the paleovalley. The stratigraphic framework will provide the base for a 3D-subsurface model.

Integrated bio-, chemo-, event and sequence stratigraphic correlations of Upper Cenomanian (M.-geslinianum- and N.-juddii-zonal) successions in several basins around the Mid-European Island (Münsterland, Lower Saxony, Subhercynian, Saxonian and Danubian Cretaceous basins) reveal a conspicuous sedimentary cyclicity that reflects high-frequency sea-level changes paced by long and short eccentricity (l-ecc. and s-ecc.) cycles of the Milankovitch band. Resting on a conspicuous mid-Late Cenomanian unconformity of 3rd-order (SB Ce 5), the following depositional sequence DS Ce-Tu 1 consists of three high-frequency sequences of 405 kyr up to its terminal sequence boundary, i.e., SB Tu 1 in the Lower–Middle Turonian boundary interval. The lower l-ecc. cycle of DS Ce-Tu 1 ranges up to the Cenomanian–Turonian boundary (CTB) and consist of four shallowing-upward cycles of ca. 100 kyr in stratigraphically complete basinal successions; sections located towards the basin margins are commonly missing the lowermost s-ecc. cycle, reflecting the lack of accommodation associated with the sea-level fall and lowstand across SB Ce 5. A major marine onlap started with the second s-ecc. cycle that is associated with the inter-regional plenus Event. Up-section, two additional shallowing-upward s-ecc. cycles up to the CTB record the infilling of the accommodation generated by the plenus Transgression. A moderate unconformity at the top of the uppermost s-ecc. cycle terminates the latest Cenomanian high-frequency sequence that represents a l-ecc. with four s-ecc. (405 vs. 100 kyr) cycles. Another major transgressive pulse at the base of the following high-frequency sequence culminated in a global earliest Turonian maximum flooding interval at ca. 93.8 Ma.

Die Elgersburg-Formation befindet sich in einem ca. 6,5 km (OSO-WNW) x 1,5 km (SSW-NNO) kleinen Teilbecken innerhalb des spätkarbonisch-permischen Thüringer-Wald-Sedimentbeckens. Aufschlüsse der Elgersburg-Formation in diesem Teilbecken, dem so genannten Elgersburger Becken, gibt es bei Elgersburg und Roda. Amtliche geologische Karten gliedern die Elgersburg-Formation in sieben Untereinheiten: Schwalbenstein-Konglomerat, Wolfstein-Rhyolith, Elgersburg-Rhyolith, Rodaer Melaphyr, Rodaer Sandstein, Elgersburger Sandstein und Totenstein-Konglomerat. Sie sind durch Steilwände, Straßenanschnitte, auflässige Steinbrüche, Baumwurzel-Aufschlüsse oder Lesesteine nur lokal aufgeschlossen. Mit einem GPS-Handgerät wurden die Koordinaten der gegenwärtigen Aufschlüsse gemessen. Zusätzlich wurden die Lithologie, Lithostratigraphie und Fallrichtung/Fallwinkel der Schichtung vor Ort dokumentiert sowie die Aufschlüsse mit einer Digitalkamera fotografiert. Nach bisherigen Ergebnissen scheint der Rodaer Sandstein räumlich begrenzte Einschaltungen innerhalb des Schwalbenstein-Konglomerats zu bilden. Die direkten lithostratigraphischen Grenzen des Elgersburger Sandsteins sowohl zum unterlagernden Schwalbenstein-Konglomerat als auch zum überlagernden Totenstein-Konglomerat sind nicht gut aufgeschlossen. Ein realistisches Auskartieren des Rodaer „Melaphyrs“ mittels Lesesteinen ist gegenwärtig schwierig. Zur Visualisierung zuvor bestehender Daten wurde das digitale Geoinformationssystem qGIS verwendet. Digitale GK25-Kartenblätter (5230 Oberhof, 5231 Ilmenau-Nord, 5330 Suhl, 5331 Ilmenau) wurden aus dem Antares-Kartendienst des TLUBN kopiert, mit qGIS georeferenziert und als Karten-Layer importiert; Lithostratigraphie und tektonische Störungen wurden als Shapefiles neu erstellt und dabei vereinheitlicht bzw. stellenweise vereinfacht. Mit Hilfe dieser Software lassen sich die dokumentierten Aufschlüsse auf einer geologischen Übersichtskarte digital georeferenzieren. Dadurch entsteht in qGIS ein digitales geologisches 2D-Modell des Elgersburger Beckens. Das Modell ermöglicht Skalierungen und digitale Messungen sowie GPS-Koordinaten-basiertes Plotten weiterer Aufschlüsse im Rahmen anhaltender Geländearbeiten.

The Mid-Brunhes Transition is not as prominent as the Mid-Pleistocene Transition, but nonetheless an important step in the Quaternary climate evolution. Here we assess the patterns of the Mid-Brunhes Transition in a suite of Lake records from Eurasia, i.a. from Gamma Ray borehole logging data. Consistent with other datasets, we find that Marine Isotope Stage 14 is expressed in different intensity. Finally, we expand our data synthesis to selected loess records to check for regional consistency in the Balkan Paninsula.

In this study the factors that control the geochemical composition of terrestrial clastic sediment were defined for the first time for provenance analysis in a rift basin under humid-tropical climate conditions. We present an almost continuous geochemical profile through the Miocene to Pleistocene terrestrial clastic sedimentary fill of the Albertine Rift in East Africa in order to evaluate changes in sediment provenance and climate conditions and link it to rift evolution. The 500 km long Albertine Rift is part of the East African Rift System, forming the northern end of its western branch. Sediment samples from two areas on the Ugandan side (Kisegi–Nyabusosi and Nkondo-Kaiso area) were analysed using major and trace element geochemistry. Petrographic and mineralogic data including heavy mineral spectra and clay mineralogy were largely available from published data. To best possibly eliminate a grain size effect, the samples were separated into two grain fractions: clay/silt (> 63μm) and sand (63-2000 μm). On the basis of statistical analysis data were compared with published and defined provenance groups and the climate development as inferred from published data on sediment facies, clay mineralogy and pollen analysis. First results indicate for instance that trace element indicators Th/Sc and La/Sc increase upsection, which is in line with increased local tectonic activity due to uplift of the Rwenzori mountains and resulting rift inversion during the Pleistocene. Climate indicators CIA and CIX show maximum values for the clay fractions during the Pliocene likely due to highest humidity at this period.

Sabah forms the northern part of the island of Borneo, which is situated at the southwestern South China Sea (SCS) margin. The Cenozoic sedimentological record includes deposits related to the formation of the SCS and the demise of its predecessor, the Proto-South China Sea (PSCS). The Paleogene was characterised by deep marine turbidite sedimentation on the south side of the PSCS, which was subducted beneath the Cagayan Arc and North Sabah. The Early Miocene Sabah Orogeny eliminated the PSCS and several mélanges were formed. Zircons from the mélanges and turbidites indicate magmatism associated with the PSCS subduction continued until c. 19.6 Ma. Immature mineral assemblages and detrital zircon age spectra suggest a partly northern source. The collision deformed and exhumed the deep marine rocks, and is marked by the Top Crocker Unconformity (TCU). Post-TCU Neogene sedimentary rocks were deposited in fluvio-deltaic to shallow marine environments and are compositionally mature with a quartzose recycled orogenic source, and ultra-stable heavy mineral assemblages dominated by zircon, tourmaline and rutile (ZTR). The lower Neogene formations have substantial amounts of chrome spinel, while upper Neogene formations are almost devoid of chrome spinel and have higher contents of ZTR, suggesting two Neogene sedimentation cycles, both with sources in Sabah. Based on sandstone petrography, heavy mineral assemblages and detrital zircon ages, sediment sources for the first cycle included recycled Paleogene turbidites with input from uplifted peridotites, while the second cycle was mainly sourced from recycling of older Neogene fluvio-deltaic formations with input from Paleogene turbidites.

The working area is situated in the Monticiano-Roccastrada Zone, an interfering metamorphic core complex of Tertiary age - constituent of the Mid Tuscan Ridge - , where subduction-related, blueschist facies metamorphosed siliciclastics (350-400°C, 0.7-1.1GPa) are exposed. Geological survey at the 1:10.000 scale resulted in the differentiation of tectono-stratigraphically homogeneous subzones, characterised by distinctive Carboniferous lithofacies as well as Tertiary-Quaternary deformation and metamorphism. The stratigraphic base of each subzone consists of a condensed, fossil-poor sequence, deposited in an epicontinental, shallow marine, starved, dysoxic to anoxic basin (Late Emsian - Early Carboniferous). It is supposed that the depositional conditions in this basin were influenced by palaeoenvironmental crises. Its Early Carboniferous extensional fragmentation - interpreted as marine failed rift event - resulted in the formation of different coeval, predominantly siliciclastic depositional areas forming a highstand systems tract above a downlap surface. The proximality trend is - in recent coordinates - westbound and the discerned sedimentary environments, separated by normal faults, consist in the inner shelf, outer shelf, lower slope, base of slope and basin margin. The sudden onset of this mass-flux was probably connected with the Hangenberg Event. Deposition of these fossil-poor sediments occurred under hothouse conditions and was influenced by tropical storms, which generated tempestites and triggered turbidites, bypassing the outer shelf sediments. Rare brachiopods sampled from there resulted in the identification of Antiquatonia Miloradovich, 1945 (Viséan-Serpukhovian). The formations were covered by regressive, littoral-deltaic siliciclastics (Permian - Early Triassic) and the Verrucano Group (?Middle Triassic).

The Alps-Rhine graben system connects the Swiss Molasse basin with the French-German Rhine rift basin. Several tectonic, climatic, and anthropogenic changes have impacted its development from the Oligocene to today. Sediment transfer is complex due to river segmentation, sediment recycling, and changing source areas in response to drainage reorganizations. This contribution provides new insights into the system dynamics by analyzing the provenance of paleo-Rhine deposits using garnet geochemistry. We present new results from ~70 modern, Pleistocene, Pliocene, and Miocene deposits. Our results show that (1) the rift shoulders supplied the bulk of sediment to the Rhine graben in Miocene and Pliocene times, (2) rift shoulder sources can be discriminated, and sources changed several times in the Pliocene, implying significant system dynamics, (3) a reorganization at the Plio/Pleistocene boundary was caused by the inclusion of the Alps into the drainage, (4) the major sediment source in the Pleistocene Rhine graben is the recycling of Molasse deposits, (5) Alpine sediment was transferred for over 500 km into the Lower Rhine graben during the earliest Pleistocene without significant signal modification, and (6) the Pleistocene deposits in the Upper Rhine show a stable composition, possibly due to reworking, and do not reflect the significant Pleistocene climate dynamics. We conclude that provenance analysis in complex systems is key to understanding system dynamics and drainage reorganizations, however, it is not necessarily able to resolve glacial-interglacial climatic changes at a basin scale.

The uppermost interval of the Agua de la Mula Member (Agrio Formation, Lower Cretaceous, Neuquén Basin, Argentina) comprises a siliciclastic-carbonate succession, representing a transition from distal to marginal-marine systems. The present study aims to understand the spatial and temporal variability of this system. Sedimentary logging, high-resolution 3D models, facies and architectural analysis were carried out in two outcrop sectors, 10 km apart from each other. The studied interval (80 m thick) shows a general shallowing-upward stacking composed of smaller-scale coarsening-up intervals (~10-15 m) having beds compositionally ranging from pure siliciclastic to pure carbonate. Basal cycles are composed of siliciclastic muddy facies grading to HCS-sandstones, interpreted as offshore-transition environments were settling, fair-weather and storm-wave processes prevail, with occasional interbedded floatstones interpreted as marine transgressions or carbonate-rich input streams due to storm events. Upper cycles are dominated by tabular to lenticular muddy to sandy mixed deposits mostly produced by unidirectional currents interbedded with extensive carbonate-dominated beds mostly comprising cross-stratified oolitic grainstones. These intervals were interpreted as a marginal-marine deltaic system were fluvial currents and wave reworking coexist as dominant processes, and riverine-supplied siliciclastic sands were mixed with an intermittent carbonate input or production. Furthermore, towards the top of this interval, a tidal influence is suggested due to the presence of heterolithic layers, mudstone drapes and scarce microbialites. The compositional and processes variations observed cannot be satisfactorily explained by simplistic facies models. This work discusses a new approach to explain compositionally mixed facies variations when making detailed paleoenvironmental characterizations.

In the Dinarides, a series of intramontane basins hosted long – lived lakes that developed during the Miocene, known as the Dinarides Lake System. Sinj Basin is one of the best studied among them, providing insights into the paleogeographic evolution of the region. A chronostratigraphic framework was initially established in the NW part of the basin using paleomagnetic data and calibrated by Ar-Ar dating of intercalated volcaniclastic deposits. However, the tectonic setting and timing of deposition are still a matter of debate, as subsequent U-Pb dating of Miocene bauxites in the SE part of the basin demonstrated that lacustrine flooding was diachronous. This study aims to provide new constraints on the evolution of the Sinj Basin based on U-Pb zircon geochronology of volcaniclastic deposits from the NW, central, and SE parts of the basin. After the separation of the heavy-mineral fraction from the samples, individual zircon grains were handpicked using a binocular microscope. These were imaged for typology with a scanning electron microscope, before being mounted in epoxy resin. Subsequently, cathodoluminiscence images were produced from polished mounts to gain information about internal structures. U-Pb isotope analyses were obtained using laser ablation‑inductively coupled plasma mass spectrometry (LA–ICP–MS). The obtained ages range between ~18 and ~15 Ma and provide new constraints on the timing of initial lacustrine flooding, and will aid in refining the timing of the Miocene extensional episode. Additionally, a wide spectrum of detrital zircon ages was obtained, reflecting the pre-Miocene geodynamic history of the Dinarides.

The study of natural climate archives is a significant method to understand past environmental conditions and depositional processes. Investigating Central German lignite is particularly suitable, as it serves as an environmental and climate archive, formed from Tertiary mires and their ecological and climatic conditions.

The petrographic composition of lignite is greatly influenced by the plant communities that formed the paleo-mires, serving as direct indicators of the climate and environmental conditions of that era. These plant communities developed in cyclic sequences, progressing from coniferous swamp forests and angiosperm-dominated peatlands to reed marshes and pine woodlands, culminating in raised bogs.

In this contribution, detailed petrographic and facies analyses of lignite seams are provided to show insights into the physicochemical and ecological conditions of these ancient marsh sequences. Field mapping and core logging at the open-pit mines Profen and Vereinigtes Schleenhain in Central Germany were conducted. Taken samples were analysed macropetrographically, as well as microscopically in terms of maceral analysis and moor facies analysis.

The resulting depositional model reconstructs the development and disturbances of the paleo-mires, revealing external environmental influences. It demonstrates the sequence of moor facies cycles and identifies areas with peat fires or the drying out of the marsh. This includes information on plant communities, groundwater levels, oxygen and nutrient availability, and climatic conditions during deposition. By correlating this information throughout different parts of the Central German lignite basin, new insights into its depositional model are provided.

The ca. 3.22 Ga Paleoarchean Moodies Group in the Barberton Greenstone Belt (South Africa) represents one of the oldest shallow-marine quartzose sedimentary systems on Earth. Due to early silicification, sedimentary structures in the 3.7 km thick succession are usually well-preserved, allowing a detailed analysis of environments and surface conditions during the development of early life on Earth. The Moodies Group was cored in the framework of International Continental Drilling Project (ICDP) “Barberton Archean Surface Environments” (BASE). Here, we focus on the fluvial-marine transition zone in the Moodies Group using outcrop data and cores recently extracted in the so-called Lomati Delta Complex (LDC, Sites 4A-C). To reveal the dominant sedimentary processes within this dynamic depositional environment, we present results from petrography and detailed sedimentological logging in cores and outcrops.

The LDC is a stratigraphic unit with a wedge-shaped geometry that is approximately 300 m thick at its thickest point and pinches out over a distance of 7 km. The deposits consist of cross-bedded siliciclastic coarse-grained sandstones and conglomerates that transition into finer-grained and tuffaceous sandstones. Sedimentary structures include tangential and tabular cross bedding, desiccation cracks, conglomeratic beds, rare microbial mats, and soft-sediment deformation related to fluid escapes. Based on these features, the LDC has been interpreted as a fluvial-marine system with highly variable energy conditions, likely linked to the ephemerality of local rivers. This analysis provides the sedimentological context for follow-up geochemical and stratigraphic work, aiming at a detailed reconstruction of Paleoarchean environmental dynamics and conditions under which early life spread.

The floors of river-valleys range from kilometer wide, densely populated plains to deeply incised gorges with narrow or no floodplains. Valley cross-sections are the product of the interplay between tectonic uplift and erosion by rivers. Rivers deepen valleys by cutting into the underlying bedrock or sediment deposits and widen valley floors by lateral erosion of enclosing valley walls. While the incision rate is thought to mainly compensate tectonic uplift, little is known about the controls of valley widening and valley-floor width.

Field measurements of valley floors are sparse, but generally indicate that valley floors are wider at sites of greater river discharge and in softer lithologies and narrower with enhanced uplift. However, order-of-magnitude scatter in those datasets suggest further, so far unknown controls on valley-floor width. Here, we systematically quantify valley-floor widths along 84 rivers draining the Western Andes. At each of the ~126,000 measurement sites, we quantify four potential control parameters on valley-floor width (river discharge, uplift rate, lateral sediment supply from valley walls, and rock erodibility) and investigate their respective influence. In general, river discharge seems to be the most important control parameter on valley-floor width at locations close to the ocean at low elevations, while uplift and/or wall height becomes more important at high elevations farther away from the ocean. A better understanding of controls on valley-floor evolution will both enhance future prediction of valley floor response to climate change and enable past climate and tectonic reconstructions from valley topography.

Orogenic Au deposits formed in metamorphic belts over most of the Earth history and the genetic models developed since the three last decades aim to provide a general model for these gold-only deposits. However, some deposits, known as orogenic gold deposits with atypical metal associations, show enrichment in base and critical metals, mainly Cu, Co, sometimes Ni, Sb, U and (REE) that are not explained by the current models (i.e. metamorphic devolatilisation, subcrustal fluids, magmatic-hydrothermal model). The Pohjanmaa Belt in western Finland hosts both typical and atypical gold mineralization and is a natural laboratory to decipher the genesis of orogenic Au-Cu-Co-Ni deposits and establish a genetic deposit model including both type of deposits. This study explores the origin and nature of the mineralizing fluids and precipitation mechanisms by combining multiple methods as follows:

(1) microthermometry and in-situ geochemistry on well preserved primary fluid inclusion assemblages;

(2) whole rock geochemistry for basic geochemical characterization and identification of metal enrichments in hydrothermal alteration zones;

(3) in-situ geochemistry on hydrothermal mineral separates (amphibole, biotite, chlorite, sericite) to highlight potential sources of fluid and metals;

(4) Halogen ratios (Cl, Br, I) for identification of potential fluid sources, including evaporites;

(5) In-situ S isotope analysis and geochemistry of sulfides to characterize the S source, redox-related precipitation mechanisms and link with the mineralizing fluids.

Research cruise SO299 to the New Ireland Basin, Papua New Guinea, discovered the active Karambusel vent field that combines characteristics of magmatic-hydrothermal venting and hydrocarbon seepage. The vent field is located at an eruptive centre on the western flank of Conical Seamount, previously known to host epithermal-style mineralization near its summit. Mineralization at Karambusel consists of disseminated sulfides and polymetallic epithermal amorphous silica veins crosscutting altered ankaramite breccias. Gold occurs as up to 20 µm sized electrum grains (Au/Ag = 5-12) in the matrix of amorphous silica veins and associated with Zn-As-Sb-Ag sulfosalts resulting in bulk rock concentration of up to >30 ppm Au. The main Au precipitation stage was overprinted by a younger Hg- (up to 500 ppm), Sb- (up to 5850 ppm), and As-rich (up to 6.5 wt.%) stage possibly related to the currently active venting of methane-rich, low-temperature (up to 50°C) fluids. Variable δ³⁴S (-14 to 2‰) in sulfides from different stages suggest complex S isotope fractionation processes related to magmatic, hydrothermal, and biogenic processes.

Here, we use a combined approach of bulk methods and high-resolution sulfide trace element and S isotope micro-analysis to reveal the enrichment processes of vein-style submarine precious metal mineralization. Comparison of our results with the Au-rich mineralization at the summit of Conical Seamount (up to 230 ppm Au) and with the world-class Ladolam Au deposit (50 Moz Au) on nearby Lihir Island will allow us to develop a comprehensive mineralization model for Karambusel, which may also be linked to active hydrocarbon seepage.

The Eocene to Miocene Urumieh-Dokhtar Magmatic Arc (UDMA), Iran, hosts numerous porphyry Cu deposits including the large Sarcheshmeh and Miduk deposits. The formation of porphyry intrusions with economic ore deposits is restricted to the Miocene arc magmatism in the southeast. In this study, a compiled arc-wide geochemical dataset of Eocene-Miocene magmatic rocks was combined with new whole-rock geochemical and isotopic data from Sarcheshmeh and Miduk drill cores to decipher the magmatic evolution of the UDMA. Two magma series with typical subduction zone-related geochemical signatures exist in the UDMA, which both range from ~50 to 75 wt.% SiO₂ implying magma formation in the mantle followed by crystal fractionation. The Eocene-Oligocene magmatic rocks along the entire arc and Miocene rocks in the central UDMA are calc-alkaline and characterized by Dy/Yb systematics indicating amphibole fractionation. By contrast, Miocene magmatic rocks in the southeastern UDMA have high La/Yb and Sr/Y resembling adakitic compositions. These were previously attributed to garnet fractionation due to extensive crustal thickening during continent collision in this region. However, we do not find evidence for garnet fractionation in the Sarcheshmeh and Miduk samples, nor did residual garnet affect partial melting in the mantle, which is consistent with pressure conditions corresponding to a crustal thickness of ~45km in this region. The compositions of the UDMA magmatic rocks suggest a sediment component derived from the subducted slab, with the high La/Yb and Sr/Y of the Miocene porphyry rocks possibly reflecting either slab melts of sediments with residual garnet or variable degrees of melting.

The worldwide progressing green energy transition requires high quantities of critical raw materials such as Ni, Cu, Co and platinum-group elements (PGE). The demand for these metals in Europe has largely been covered by imports, however, frequent supply shortages resulted in new exploration and research interests regarding domestic resources. With view on Germany, exploration efforts are currently focused in the Lausitz area. There Ni-Cu-(PGE)-bearing magmatic sulfides are associated with dike- to stock-shaped Devonian gabbroic intrusions that crosscut Cadomian granodiorites of the Lausitz Block (northern Bohemian Massif). Several of these intrusions, i.e. Sohland-Rožany, Angstberg and Sora, already revealed spatially limited ore bodies with disseminated, net-textured and massive sulfides as well as sulfide-matrix ore breccias, which are characterized by high Ni, partly elevated Cu, Co and highly variable Pt, Pd and Au tenors. Another mineralized gabbroic body is the ~376 Ma stock-shaped Valtengrund intrusion. The mineralogical and geochemical features of the Valtengrund magmatic sulfide enrichment have hitherto not been studied in detail and are the focus of this study. First findings show that the gabbroic body represents a composite intrusion with fine- to medium-grained olivine-gabbronorite and olivine-gabbro at the margins and medium- to coarse-grained gabbro in the central parts. Magmatic sulfides are hosted in the olivine-gabbronoritic lithologies along the footwall and hanging wall contacts of the gabbroic intrusion. The mineralized samples show variable ore textures including globular and interstitial disseminated sulfides as well as up to 5 cm sized variable-shaped sulfide patches with pyrrhotite, pentlandite and chalcopyrite as major sulfide phases.

The Swedish part of the Fennoscandian Shield, hosting the largest rare earth element (REE) reserve in the EU and several active base metal mines, shows great potential for yet undiscovered critical raw material deposits. The new Marie-Curie project (ID: 101154535), "CRITTER: Strengthening the Critical Raw Material Independence of the EU through Thermochronology," aims to reconstruct the thermal history of the Bergslagen ore province. We will employ in-situ Rb-Sr dating of mica at the University of Gothenburg and zircon and rutile in-situ U-Th-He dating at the University of Göttingen. These interdisciplinary methods will be applied to the least altered and deformed granites and pegmatite bodies around key mineral deposits (e.g., Bastnäs REE and Håkansboda Cu-Co deposits). The new data will fill a crucial knowledge gap in understanding the timeline of cooling, reheating, and potential ore re-mobilization events for the last 1.8 Ga.

Geoscience investigations by nature require the ability relate data across scales. For example, observations made from the meter to sub-micron scales may be used to understand geological processes over much greater length and time scales. An emerging challenge is the ability to collect accurate, precise and high resolution geochemical and mineralogical data at the hand specimen scale that allows: 1) data at the scale of typical human observation (e.g., visual logging of drill core); 2) robust down-sampling decisions that will make the most efficient use of more expensive analytical techniques and thus best leverage the data from them, and 3) provide a scaling step from micron-scale observations (e.g., SEM) back to those of a drill hole, deposit, or even regional scale. Within this context, and that of the growing need to integrate multiple data types within more expansive datasets, additional challenges are apparent regarding data accessibility and operability that will require a collaborative approach between instrument vendors, those who capture data, and end-users to solve. This poster will present how micro-XRF mapping data helps to bridge the gap in scale between large-scale characterization and focused fine-scale analysis, but equally and important, present discussion points regarding the challenges of data accessibility that limit overall utility in mineral deposit discovery and extraction.

Durch die Energie- und Mobilitätswende, den Klimaschutz, den generellen technologischen Fortschritt und die Digitalisierung steigt global die Nachfrage nach mineralischen und metallischen Rohstoffen. Der zunehmende Rohstoffbedarf verdeutlicht die Notwendigkeit eines verantwortungsbewussten Bergbaus. Recycling und Kreislaufführung steigen, können alleine den Rohstoffbedarf oder die benötigte Materialqualität nicht decken. Deutschland und andere europäische Länder verfügen kaum mehr über Großunternehmen im Bereich metallischer Rohstoffgewinnung mit globaler Handelskette. Dahingegen agieren andere Länder global und investieren direkt in den Bergbau, beispielsweise in Afrika. Afrikanische Länder beherbergen eine Vielzahl metallischer Bodenschätze und mineralische Rohstoffe, darunter besonders auch Botswana, Marokko, Namibia und Simbabwe. Diese Länder bieten länderspezifische Möglichkeiten im Bereich Bergbau, der Aufbereitung und der Rohstoffsicherung, die aktuell noch kaum von deutschen Investoren wahrgenommen werden. Die Rohstoffsicherung und die resiliente Versorgung mit kritischen und strategischen Rohstoffen sind nicht nur für den technologischen Fortschritt und zum Erhalt der Industrie in Deutschland notwendig, sondern auch für strategische Sektoren der EU wie Erneuerbare Energien, Elektromobilität sowie Verteidigung und Raumfahrt.

For its thermo-electric properties, the mineral tennantite is a much sought-after commodity which occurs in historic mine waste heaps. The mining site Nöckelberg, located near Leogang in the province of Salzburg, offers such a waste heap. Here, copper, nickel and cobalt mining took place in the 19^th and early 20^th century. Dominant ore minerals include tennantite, chalcopyrite, cinnabar, galena and bornite, embedded in a matrix of magnesite, dolomite and quartz. The waste heap consist of pebble- to boulder-sized rock fragments which still contain visible quantities of tennantite.

To define the geometry of the waste heap, quantify its volume and characterize the ore content, a multi-disciplinary study was carried out. Terrain modelling aimed at reconstructing the ground surface prior to mining. Geochemical analyses comprised whole rock XRF to quantify element concentrations, XRD to describe bulk mineralogy, and SEM to study mineral composition.

3D modelling reveals a mean waste pile thickness of 4.2 m and a volume of 26,000 m³. The material contains 4% copper iron sulfides (bornite, chalcopyrite and tennantite) and As and Cu elemental concentration of 2% and 3% respectively. The 100 µm-sized tennantite grains are intertwined with chalcopyrite and show a typical composition of 37 at.% Cu, 10 at.% As, 3 at.% Sb, 7 at.% Fe and 43 at.% S.

These results indicate a (small) tennantite resource potential sourced from mine waste material. Separation and beneficiation tests are currently ongoing.

The START project is co-funded by the European Union. Views and opinions expressed are those of the authors.

A novel spectral gamma logger is presented as a versatile instrument in laboratory or in situ gamma ray and K-U-Th concentration pattern logging. It includes an array of novel compact and high sensitivity radiation detectors embedded in efficient shielding and in a close contact with the measured sample (core). Its design minimizes the requirement for shielding size and weight while achieving the accuracy and precision of larger conventional setups.

The revolutionary modular architecture can combine a series of standardized instrumented segments to perform simultaneous measurements along core samples and provide customizable statistical precision. The performabce of the new logger is demonstrated on several real cores from the country.

The two granite domes of Schenkenshöhe and Hegelshöhe are Sn-Li-W Greisen deposits in the eastern Erzgebirge. The Schenkenshöhe and Hegelshöhe are located approx. 5 km north of the town of Altenberg on the eastern rim of the Altenberg-Teplice Caldera (ATC) and belong to the late magmatic phase, in which highly specialized A-type granites intruded into the ATC area. In contrast to other greisen deposits the polystadial granite intrusions of Schenkenshöhe and Hegelshöhe intruded into the rim fill of the ATC. These intrusions lead to the formation of exogreisen- and endogreisen-mineralization, which are enriched in tin, lithium and tungsten. This is the reason for many years of historical Sn mining and extensive exploration phases. This exploration works mainly related to Sn mineralization with a total length of drill core of approx. 32 km in the Schenkenshöhe and Hegelshöhe areas.

The two granite domes are multiphase, granitoid intrusions that became increasingly specialized. In the process, five granite intrusions intruded, which greisenized each other due to the accompanying fluids. This results in the formation of several meter-thick bodies of greisen in the apical area of the granite cuppolas. There are two main groups of Li-bearing bright mica in both the greisen bodies and the granites, which allow conclusions to be drawn about the genetic development of the granite intrusions and the subsequent greisenization phases and hydrothermal overprinting. These geological conditions can be compared with the Altenberg and Zinnwald deposits.

Creating a Critical Metal by-product from an active mining operation is a sustainable way to enhance Europe's self-reliance on these metals without the need to open new mines. In this study, we investigate the presence of Au, Ag, and any Critical Metals (such as Co, Cu, or Ni) in the sulphide-rich flotation tailings at Kaunis Iron's Tapuli mine.
Kaunis' plant produces a magnetite concentrate using two magnetic separators. A newly installed flotation circuit extracts sulphides from the final product. The flotation tailings are therefore enriched in pyrrhotite, and---due to poor liberation in grinding---also pyrite and chalcopyrite to certain extents. Ingoing trace contents of e.g. Cu are enriched in the flotation tailings to potential ore-grade levels. Even grades below traditional ore grade in the tailings might be of economic interest hence converting the waste stream to a mineral resource.

Preliminary results include 2000 ppm Cu, 200 ppm Co, and 4 ppm Ag in the flotation tailings at a low sulphur feeding grade. Further sampling and assaying are underway, while ingoing sulphide content is steadily being increased.

The Outokumpu deposit is an ultramafic-hosted VMS deposit in Eastern Finland. It is of Paleoproterozoic age and discussed as polygenetic in origin. Its primary enrichment in Cu-Zn-Co-Ni is of economic importance. The samples are from ore-rich formations and metaserpentinites retrieved from the Outokumpu Drilling Project, a borehole that crosscut the full sequence of the Outokumpu-Jormua ophiolite. The study utilizes the petrography and mineral chemistry (EPMA, LA-ICP-MS), to distinguish different pyrrhotite and pentlandite generations that might be associated with distinct potential magmatic, oceanic-alteration hydrothermal, or metamorphic-hydrothermal ore-forming processes. It also aims to establish probable relationships between the sample types. First, we distinguished monoclinic ferrimagnetic/fm and hexagonal antiferromagnetic/afm pyrrhotite (using magnetic ferrofluid) and correlated the more Fe-rich afm modification with silicates deposition and the less Fe-rich fm modification with fractures. Three populations are distinguished in terms of Fe/S ratio, ranging from typical ratios of monoclinic modifications (0.85-0.87) to nearly troilite compositions (~0.97). The last corresponds mainly to the ore samples, where the rest to the drillcore. The Ni/Co ratios show a corresponding clustering with the mentioned Fe/S ratios, whereas the enrichments in Pb, Bi and Sn show no correlation with population. Pentlandite shows different population characteristics for the Fe/S (i.e., ~0.85 and ~1.15), and Fe/(Ni+Co) (i.e., 0.6 and ~1.25) indices. The distinction between ore and drillcore samples is expressed in the first being more Fe-rich. The Ni/Co heterogeneity and higher values are attributed to be a result of the pentlandite exsolution from pyrrhotite, exclusively shown in the ore.

The lower parts of the evaporite cycles of the Zechstein Formation within the North German Basin comprise large deposits of several 10 to 100 meters thick sulphates, intercalated with carbonate, dolomite and clay. These sulphates were deposited in the deeper parts of the basin as gypsum that underwent dehydration and compression, forming anhydrite. Also, several thin anhydrite / gypsum layers divide the thick salt deposits of the Zechstein Formation. In these stratigraphic successions of anhydrite, the deposits are often highly textured and show a broad spectrum of structures ranging from pseudomorph crystals to nodular or even layered shapes.

The precipitation of evaporates follows the solubility, resulting in the evaporitic sequence.The dissolution and recrystallisation of evaporite deposits are complex processes that are influenced by several parameters such as temperature, pressure and water availability. Therefore, at low temperatures the anhydrite deposits are supposed to be more stable than other evaporites making them a possible paleo-archive of sedimentary and diagenetic conditions. Furthermore, they can be used to infer halokinetic and halotectonic processes of evaporites.

In this study, we analyse the variation of textures, including laminated, nodular, pearl-like successions within anhydrite deposits of drilling cores and local outcrops. Based on the observation, we suggest evidence for primary and secondary processes occurring during the deposition and diageneses within different regional and tectonic settings in the North German Basin. This study will provide a broader understanding of the rheological behaviour of sulphates, which is important for future subsurface planning efforts and karst development.

Pegmatites are major hosts for critical materials and are thus crucial for the green technology transition. Age information and geochemical constraints are fundamental to understand pegmatite genesis and are thus highly valuable for spatial correlation of pegmatite bodies and for exploration.

Pegmatites commonly carry high Rb minerals such as white mica. These minerals are targeted for in-situ Rb/Sr LA-ICP-MS/MS dating. This ICP-MS has a reaction cell built between two mass spectrometers. Reaction gases such as N2O or SF6 can be induced into the cell to chemically separate ⁸⁷Rb and ⁸⁷Sr. This avoids the isobaric overlap during mass-spectrometric analysis.

LA-ICP-MS/MS Rb-Sr dating of pegmatitic mica has multiple advantages. For example, high sample throughput: the targeted minerals are main phases and rock chips or single crystals can thus be used for dating. This avoids time-consuming and contamination-prone mineral separation. In addition, pegmatitic mica often has not only high Rb mass fractions, it also has very low to neglectable common Sr. Thus, the ⁸⁷Rb-⁸⁷Sr age does not depend on the initial ⁸⁷Sr/⁸⁶Sr composition. More specifically, ⁸⁷Rb-⁸⁷Sr ages can be calculated without ⁸⁶Sr – a main difference to the conventional ⁸⁷Sr/⁸⁶Sr versus ⁸⁷Rb/⁸⁶Sr isochron approach following Nicolaysen. This age calculation strategy will be presented in this contribution using pegmatites from the Gothenburg area (Högsbo) and Mozambique as examples.

According to VDI Guideline 4640 Part 2, the design of a properly sized ground source heat pump requires the performance of a GRT to determine the thermal properties of the ground. Specific parameters to be obtained are the undisturbed mean temperature and the thermal conductivity of the lithologies present. With the first practical tests carried out in Sweden in 1995 and in the USA in 1996, the method is now well established worldwide.

The effective thermal conductivity of the ground and the thermal resistance of the borehole are estimated from the measured temperature evolution in the borehole for a given energy input/output, according to Kelvin's line source theory. While thermal conductivity values for different lithologies published in the literature and VDI Guideline 4640 Part 1 provide rough estimates, only the GRT can provide real scenario values as parameters other than mineralogical and chemical composition can affect the effective thermal conductivity.

In reviewing the GRT reports from across Schleswig-Holstein, we observed very high effective thermal conductivities in some locations that could not be explained by lithology or incorrectly performed measurements or installed geothermal probes. Groundwater flow and, in some coastal areas, even tidal currents were found to influence thermal conductivity.

The ongoing structural change from the hydrocarbon industry towards sustainable green energy is one of the challenges Europe (and the world) faces recently. In Germany, there are approximately 15,000 boreholes with depths ≥ 400 m (deep wells). Transgeo, an Interreg funded transnational project aims at determining the potential of such boreholes for the extraction of Geothermal energy in Germany and 4 other Central European countries. During the 3 years of project duration, data of the deep drillings will be gathered, summarized in databases, and then fed into a web-based IT-tool, showing the potential of the deep wells for geothermal energy extraction. The information gathered and analyzed by the tool comprises not only aspects like the depth and the temperature gradient, but also geological, geophysical and technical information of the wells, as well as the local socioeconomic background and the legal situation. Within the project area, drill holes of the North German Basin, the Molasse Basin, the Vienna basin and the Pannonian basin will be taken into account. Within the North German Basin, about 1330 drillings lie in within the borders of the Brandenburg State. The purpose of these drillings was manifold and included hydrocarbon exploration (ca 50%), geological mapping (13%), underground storage (12%) and other mineral resource explorations (mainly coal, iron, copper, and uranium). Only about 2 percent of the drillings are still “open” (not plugged and/or cemented) and 9 percent count on temperature logs. Temperature gradients vary among the eastern North German basin, influenced mainly by Zechstein thickness.

As part of the German Continental Reflection Seismic Program (DEKORP), the deep seismic reflection profiles GRANU-9501 and MVE-90 were acquired in the Saxothuringian Zone to gain insights into the region’s crustal structure including the Moho. The GRANU-9501 profile is situated in the Thuringian-Franconian-Vogtland Slate Mountains. The east-west oriented MVE-90 crosses GRANU-9501 in the SW Vogtland almost perpendicularly.

The development of advanced seismic processing and imaging methods, as well as the increase in computational capacities enabled us to re-process these datasets to obtain an improved image of the crust and upper mantle in the area.

We applied Kirchhoff prestack depth migration as well as Fresnel-Volume-Migration approaches and compiled the results to a pseudo-3D image together with additional geophysical and geological information.

The results came recently into focus as profiles GRANU-9501 and MVE-90 cross the hidden Schönbrunn/Eichigt granite complex. This pluton is the investigation area of the project E4Geo, in which the principal aim is to get a better understanding of deep fault-bound hydrothermal systems related to this granite complex.

In this talk, we will present the seismic images obtained from re-processing compared to previous results as well the resulting geological interpretation and open questions.

Accurate geothermal reservoir modeling relies on a comprehensive understanding of subsurface properties. This study focuses on the Schönbrunn/Eichigt granite complex in Saxony, aiming to develop a detailed 3D model for geothermal resource assessment.

We present an integrated approach that combines geological, geophysical, and petrophysical data, including gravity, magnetic, and seismic data. Through stochastic inversion modelling, we construct a robust 3D model of the granite complex, providing insights into its structure and composition while quantifying uncertainties.

The main objective is to develop a parameterized 3D subsurface model, serving as a boundary condition for geothermal fluid simulation. High-resolution voxel models of density and susceptibility distribution are generated, enhancing our understanding of the subsurface, including the fracture network within the granite.

Incorporating newly acquired gravity and seismic data will improve constraints on the shallower part of the model, crucial for accurate geothermal simulations. This integrated 3D modeling approach facilitates the characterization of reservoir characteristics, advancing our understanding of granite reservoirs in the Schönbrunn/Eichigt complex.

By quantifying uncertainties and employing 3D modeling techniques, our study provides valuable insights for geothermal exploration and development, contributing to sustainable energy solutions.

Long-term safety assessments for nuclear waste disposal face considerable challenges due to uncertainties resulting from the complex geological, geochemical and environmental processes. This work focuses on enhancing the predictive capability of reactive transport models (RTM) for radionuclide migration in fluids within repositories in crystalline host rock. In particular, the work is focused on investigating the influence of uncertain parameters on radionuclide sorption behavior in crystalline rocks. This is achieved by means of systematic Global Sensitivity analysis (GSA) techniques. The distribution coefficient (Kd) is a key parameter quantifying sorption behavior, obtained by means of geochemistry databases. A Quasi Monte Carlo sampling of input parameters, including mineral composition, pH/Eh, and Uranyl concentrations, was employed to study their effects on Kd values. GSA identifies the important variables affecting the uncertainty in the assessment results. Two GSA methodologies where utilized in this work, namely CUSUNORO and High Dimensional Model Representation (HDMR). By performing CUSUNORO and HDMR together, we capture first-order non-linear and second-order effects, respectively, revealing interaction effects between input parameters on the distribution coefficient. Moreover, the compositional data sampling poses a challenge due to the interdependencies which can alter the results of sensitivity analysis. To address this, we implemented transformation techniques to mitigate the interdependency problem. Our findings contribute to a deeper understanding of these processes, providing valuable insights for enhancing the reliability and robustness of long-term safety assessments for nuclear waste disposal sites.

Future glaciations are considered as a major challenge for the long-term safety of repositories for highly active radioactive waste, which has to be assessed for up to one million years. Especially the incision of subglacial tunnel valleys reaches depths of up to 600 m b.s.l., which is within the depth range considered for repositories.

Tunnel valleys are ubiquitous features of formerly glaciated sedimentary basins and are characterised by undulating basal profiles, abrupt terminations and steep flanks, all indicative of their subglacial formation by pressurised subglacial meltwater. To assess the potential of future tunnel-valley formation and its implications for long-term safety, we apply a multi-directional approach:

• By mapping the distribution and maximum depths of Pleistocene tunnel valleys in Germany a zonation map of the regional depth of erosion was generated. These depth zones may be used to define a regionally variable additional depth for a repository (Breuer et al., 2023).
• To understand the impact of pre-existing geological structures on tunnel-valley formation we compared the trends of Pleistocene tunnel valleys to faults, salt structures and the large-scale geometry of the North German Basin. A correlation between those features was only locally observed, presumably if ice-advance directions matched the major structural trends.
• High-resolution 3D seismic data from the central North Sea are analysed to gain insight into the morphology and depositional architecture of Pleistocene tunnel valleys. These insights may serve as analogue for other, less well-resolved tunnel valleys.

References:

Breuer et al. (2023), E&G Quat. Sci. J., 72, 113-125, DOI:10.5194/egqsj-72-113-2023

The Middle Jurassic Opalinuston-Formation (OPA) in Switzerland and Southern Germany is considered as a potential host rock for the deep geological disposal of high-level radioactive waste. For the present study, core samples from the Mont Terri rock laboratory (Switzerland) and from the BGR research project "Sequence Stratigraphy of the Aalenian in Southern Germany" (SEPIA) are investigated using a facies-based approach including mineralogical and geochemical analyses. Special focus is put on the degree of ordering of the irregular illite-smectite (I-S) interstratified clay minerals, which are responsible for the sorption of radionuclides and swelling properties of the rocks.

The results support the classification of OPA into several facies types. The clay fraction present in the samples varies according to these facies, consistent with variations in cation exchange capacity. For the Mont Terri site, crystal structure-based Rietveld refinement indicates strong similarities in the nature of disorder of the interstratified I-S. In all facies and subfacies of the investigated samples from the Mont Terri rock laboratory, the amount of illitic layers in the I-S varies between 73% and 85 % for all refinements and ordering types.

Our ongoing effort is to compare these results with crystal-structure based Rietveld measurements from the OPA in Southern Germany. This comparison will improve our understanding of how results from the Mont Terri rock laboratory can be transferred to claystone formations in Germany.

A robust prediction of recent crustal stress is critical for selecting sites and designing high-level radioactive waste repositories, ensuring their long-term safety and environmental protection. It is also vital for underground activities like hydrocarbon or geothermal energy production. However, while the World Stress Map offers comprehensive information about the orientation of maximum horizontal stress for Germany, reliable stress magnitudes are only accessible in specific areas. To overcome this challenge of limited data availability, geomechanical-numerical modelling is used. Another challenge is, that the crustal stress field is influenced by factors of varying scales, such as plate boundaries and topography. This poses a challenge for numerical stress prediction, as there is a conflict between model size, resolution, and computing resources. Small-scale models offer high resolution but lack incorporation of large-scale influencing factors, while large-scale models have limited resolution.

To solve this, we use models of different scales - a regional model of 200 * 80 km² with 12 units and a site model of 20 km * 60 km² with 18 units and a submodeling approach, combining them to achieve a comprehensive understanding of crustal stress distribution. The research area locates between Baden-Württemberg and Bavaria, covering Teilgebiet 001 in the Molasse basin, focusing on the Opalinus clay with maximum thickness 300 meters. The regional model is calibrated using a Germany-wide stress model, which then calibrates the site model. This submodeling approach extrapolates stress tensors from the larger area to a potential site model, reducing time and resources.

Understanding the thermo-hydro-mechanical processes in various high-temperature/high-pressure underground projects, such as nuclear waste disposal, coal gasification, geothermal energy, and beyond, plays a key role in the assessment and selection of the best and most optimal project sites. Permeability is one of the most important reservoir parameters and is influenced by factors such as stress regime, temperature, rock-mineral composition, and grain size. Within the framework of the AMPEDEK project, the permeability of granites is analyzed under different triaxial stresses, temperatures (30, 60, and 90 °C), and continuous flow. These experiments were conducted using a thermo-triaxial device at the TU Darmstadt laboratory and lasted approximately 12 days each. At 30 and 60 °C, the experimental results show that the permeability changes after one load cycle are small. The initial permeability decreased from 2.72x10^-18 to 2.18x10^-18 m² and from 7.36x10^-19 to 5.78x10^‑19 m² for 30 and 60 °C, respectively. The experiment at 90 degrees showed a significant and progressive decrease in permeability starting from a mean stress of 10 MPa. The initial permeability decreased from 5.1x10^-18 to 4.48x10^-20 m² after 12 days of the experiment. It can be concluded that the coupling effect of high temperature and increased stress has a direct effect on the permeability of the sample. Additionally, two phenomena can be observed during the experiment: 1) the decrease in permeability due to the increase in mean stresses, and 2) the progressive deformation at 90 degrees, and the resulting decrease in permeability, which is amplified by the increase in stresses.

Size-dependent mechanical properties have been extensively investigated with rocks (e.g., basalt, granite, norite and marble) through compression experiments. However, the obtained empirical correlations of these rock strength properties (UCS and Young’s modules) with sample sizes show discrepancies with the ones obtained from the same experiments with some sedimentary rocks (e.g., limestone and sandstone). There is a lack of microstructural understanding of size effects. In this study, we combine petrographic analyses and uniaxial compression experiments with Rotliegend sandstone to shed light on the controlling mechanism of size-dependent rock strength. Cylindrical samples with diameters of 25, 38, 50, and 75 mm and length/diameter aspect ratio between 1.6 and 2.1 were prepared. UCS and Young’s modulus of different-size samples are systematically compared. Thin section analyses including the initial intact samples and some selected failed samples were performed to link the microstructure with the rock strength at different scales. Additionally, P-wave velocity and porosity were also measured to have comprehensive results. The ongoing experiments indicate UCS between 52.9 and 72.2 MPa, and Young’s modulus between 12.9 and 15.5 GPa. We will also make a comprehensive comparison with published results of different rock types. Understanding size effects in strength properties of sedimentary rocks may contribute to the upscaling of the laboratory results, and may also indicate the reliability of experiments performed with a smaller sample size (e.g., 25 mm in diameter), which is the most common dimension of plugs prepared from drill cores.

Im Jahr 2019 startete die European Geoscience Union (EGU) eine neue Initiative zur Verbesserung der geowissenschaftlichen Schulbildung, die Geoscience Education Field Officer (GEFO) Initiative. Sie beauftragt GEFO damit, interaktive Workshops für Lehrkräfte durchzuführen, die geowissenschaftliche Inhalte gemäß ihren Lehr- und Bildungsplänen oder Fachanforderungen unterrichten müssen.

Während eines etwa 120-minütigen Workshops machen die Teilnehmenden sich mit 6-8 praktischen Übungen und Modellversuchen aus der Earth Learning Idea-Datenbank vertraut. Dadurch lernen sie die Datenbank mit ihren Zugriffsmöglichkeiten auf derzeit 450 weiteren Earth Learning Ideas in englischer Sprache kennen, viele sind bereits auf Deutsch übersetzt. Im ersten Jahr haben 85 Lehrkräfte an den Workshops in Deutschland teilgenommen. Die Resonanz ist durchweg positiv.

GEFO kooperieren für die Workshops auch gerne mit Museen. So lernen Lehrkräfte die dortigen Angebote kennen und erhalten durch die Earth Learning Ideas Anregungen, wie sie ihre Schülerinnen und Schüler auf einen Ausflug vorbereiten können.

Das Poster zeigt den bewährten Ablauf eines Workshops, ausgewählte Rückmeldungen der Lehrkräfte und wie Sie einen Earth Learning Idea-Workshop an Ihre Einrichtung holen können.

Carbon Capture and Storage (CCS) is becoming a widely used technology to achieve the climate goals and reduce atmospheric carbon-dioxide contents and achieve net CO₂ neutrality. Over the past decade there have been an increasing number of studies on storing carbon-dioxide in saline aquifers. While reservoir properties have been well studied, less is known about caprock integrity and permeability. Therefore, we carried out permeability measurements on low-permeable rocks, as it is one of most important physical properties determining the quality of both reservoir- and caprocks. Permeability was measured using Helium, with corrections made for gas slippage using the Klinkenberg-correction on shales, claystones, and evaporites. In our measurements we noticed the effect of increased confining pressure over time, highlighting the stress equilibration of cap rocks has to be considered. For the comparative study we measured permeability of select cap rocks at a constant isostatic confining stress of 300 bar (30 MPa) over a period of 5 to 7 days to show that repeatable measurements of cap rock permeability at subsurface stress conditions require an equilibration period. This equilibration period is a function of the rocks mineralogy and texture. The results suggest, samples, which contain abundant ductile clay minerals, should be kept under elevated confining stresses for at least for 3 days to obtain reliable permeability data. Evaporite samples have been shown to be less sensitive to elevated confining stresses and show an equilibration of repeatable permeability measurements after 1,5 days.

Wasserstoff wird in Zukunft weltweit eine bedeutende Rolle bei der Dekarbonisierung des Energie- und Wirtschaftssystems einnehmen. Da die Herstellung von Wasserstoff aus erneuerbaren Energien noch vergleichsweise teuer ist, stellt sich die Frage, ob kommerziell nutzbarer Wasserstoff im geologischen Untergrund vorkommt. Wasserstoffkonzentrationen von über 10 % wurden weltweit bereits an über 300 Orten gemessen. Diese und weitere kleinere Funde haben in den letzten Jahren international das wissenschaftliche und kommerzielle Interesse an Wasserstoff aus dem geologischen Untergrund stark zunehmen lassen.

Gemessene Wasserstoffkonzentrationen ermöglichen kaum Rückschlüsse auf Bildungsmechanismen und potentielle Ansammlungen im geologischen Untergrund. Jedoch lässt die Anwesenheit von Ophiolithen auf Serpentinisierung als einen bedeutenden Bildungsmechanismus für natürlichen geogenen Wasserstoff schließen. Als weiterer wichtiger Bildungsprozess wurde die Radiolyse ermittelt. Forschungsergebnisse zeigen, dass Wasserstoffvorkommen existieren, wie zum Beispiel in Mali und Albanien. Wir präsentieren hier ausgewählte Beispiele zu geogenen Wasserstofffunden und Aktivitäten in verschiedenen Ländern, beleuchten geologische Hintergründe und ordnen veröffentlichte Zahlen zu Wasserstoffmengen im geologischen Untergrund quantitativ in den Kontext des Wasserstoffmarkts ein.

Underground hydrogen storage in porous rocks is a promising method for large-scale energy storage. However, results for the geochemical reactivity of hydrogen with reservoir rocks are still rare, particularly for their potential effects on reservoir performance. Some minerals such as hematite, pyrite, and calcite can react with hydrogen under certain temperatures. These mineralogical transformations due to the presence of hydrogen may change the pore structure and affect the storage properties. In this study, we investigated the geochemical reactivity of hydrogen with Buntsandstein reservoir sandstones, collected from hydrocarbon wells at a depth of about 2.5 km. The experiments were performed at 100 °C under 150 bar for one month. Four different scenarios including dry hydrogen, dry air, synthetic saline fluid-saturated rocks with pure hydrogen and with pure helium were systematically compared to understand the reaction attributed to hydrogen instead of fluid-rock interactions or temperature effects. Permeability, porosity, magnetic susceptibility and fluid element concentration were measured before and after experiments to shed light on the potential reaction. The results indicate that no fundamental and substantial changes in the minerals were induced by hydrogen reaction under the simulated conditions. Magnetic susceptibility reveals that no magnetic minerals (e.g., magnetite) were formed. The slight variation of permeability and porosity is mainly due to fluid-rock interaction indicated by the changes in the fluid element concentration. Our results reveal that there is no risk of hydrogen loss and reservoir (Buntsandstein sandstone) performance reduction due to geochemical reactions of hydrogen under temperatures up to 100 °C.

Underground hydrogen storage (UHS) technology promotes large-scale energy storage and balancing of energy grids due to mismatch between renewable energy production and demand patterns. As this technology is significantly dependent on the use of subsurface porous rocks for hydrogen storage, an adequate understanding of the porous media properties and flow behaviour of hydrogen is crucial for implementing UHS. Modelling porosity and permeability is vital for understanding storage and fluid flow in porous geological media such as depleted hydrocarbon reservoirs and saline aquifers. Porosity and permeability depend on the size, shape and connectivity of the pores, making modelling of pore-scale properties a challenging task in the GEOZeit project to investigate the suitability of potential sandstone formations in Germany for UHS. This work presents a pore scale Finite Element Modelling (FEM) using scanning electron microscopy (SEM) images of Bentheimer sandstone to evaluate critical reservoir properties like porosity and permeability in tandem with fluid properties and in-situ reservoir conditions, and allows the comparison with measured experimental values. The model is implemented in COMSOL Multiphysics software using the creeping flow interface which computes permeability based on Darcy’s law. The production rates of different fluids (hydrogen, nitrogen, methane, carbon-dioxide and water) were determined based on the evaluated porosity and permeability from the Bentheimer SEM image. The result of the integration of SEM scanning and computational methods to model porosity and permeability offers more insight into understanding the complexity of fluid flow in porous media for accurate assessment of the subsurface before and during UHS operations.

Among the search for naturally occurring hydrogen, serpentinization was identified as an important hydrogen producing process. As such, understanding of the formation history of typical serpentinite occurrences is critical. The Münchberg Massif in northeast Bavaria in Germany contains serpentinite bodies in the lowermost unit, namely the Prasinite-Phyllite-Series. Several of the bodies are exposed because of uplift and denudation of the Münchberg Massif. Study of these serpentenites and their geological context can give important insights into the serpentinization process. Serpentinite samples were taken at the locations of Peterleinstein and Zell, situated about 20 km from each other. Petrological analyses were carried out on the recovered samples. Samples from Peterleinstein are completely serpentinized and the serpentine has a platy structure. In samples from Zell, mesh serpentine is present together with numerous orthopyroxene and olivine relicts. The chemical analyses point to a rather harzburgitic to dunitic protolith for both locations, suggesting a depleted mantle source. However, the serpentinite at Peterleinstein is enriched in light rare earth elements and depleted in heavy rare earth elements compared to the serpentinite from Zell. This could be explained by mantle heterogeneities. The petrological and chemical differences between the studied locations show that the process of serpentinization is complex and variable. Therefore, in depth study of this process is imperative for the exploration of naturally occurring hydrogen.

In July 2023, we conducted a measurement campaign to examine soil gases from 8 locations and gases from 16 natural springs in the northwestern foothills of the Pyrenees, near Biarritz (France). The aim was to test whether natural hydrogen gas (H₂), formed by the hydration of mafic minerals in an exhumed mantle body beneath the Pyrenees, migrates to the surface along deep-rooted faults.

In-situ measurements of soil gas compositions were carried out using various methods and devices: a landfill gas analyzer GA 5000, a Testo 316 detector, a Dräger Multiwarn X-am 8000 and a portable mass spectrometer “miniRUEDI”. The concentrations of H₂ in the soil measured with these devices were in the range of 0 – 2,000 ppmv.

Further measurements of gas samples collected from springs and degassed water samples in the GFZ laboratories showed H₂ concentrations between 5 - 4,300 ppmv. The spring with the highest H₂ concentration also shows very high (65.1 vol.%) CH₄, 1.7 vol.% CO₂ and +12.7 ‰ δ¹³C (CH₄) at -12.8 ‰ δ¹³C (CO₂).

At GFZ, we also carried out noble gas analyzes on several gas and water samples using a VG 5400 noble gas mass spectrometer. The idea behind this is that when mantle minerals hydrate, noble gases released from fluid inclusions should also migrate to the surface, along with the natural H₂. However, measured noble gas isotope ratios hint at a crustal origin of both the noble gases and the natural H₂. Additional sampling and analysis are planned to verify these first insights.

Cherts are robust geological archives, yet the multitude of factors controlling silicon isotope fractionation still limit interpretations of silicon isotope signatures (δ³⁰Si). In this work, we compare petrographic features of cherts with bulk rock δ³⁰Si and major element ratios to assess the paleo-environmental significance of δ³⁰Si_chert and to investigate the possible origins of silica of Lower Carboniferous cherts from the Rhenohercynian basin. For this investigation, we selected a section on a paleo-high position in the basin that was mostly shielded from the influence of detrital material. Variations in the abundance of radiolarian molds do not appear to influence the silicon isotope signatures of the bulk chert, indicating that the original δ³⁰Si signature of radiolarians is overprinted. Instead, we observe decreasing δ³⁰Si values with increasing Al/Si, suggesting an influence of interbedded layers of metabentonites on the δ³⁰Si in chert. We tentatively suggest that the pure cherts attain a Si isotope signature that is set during equilibration of siliceous ooze with paleo-seawater.

The up to 2000 m thick Zechstein succession was deposited in an epicontinental sea during the Late Permian. These deposits are virtually fossil-free and do not contain radiometrically datable volcanic layers. Thus, chemostratigraphy is currently the best method to assign absolute ages to these sediments.

We present ⁸⁷Sr/⁸⁶Sr data of the Zechstein succession at the northern rim of the Thuringian Basin. We sampled 26 gypsum and anhydrite samples from drill cores situated at “Alter Stolberg” (Niedersachsen, Germany). The drill cores include the Werra, Staßfurt, and Leine Formations. Our data allow a chemostratigraphic age assignment of these formations at 257-254 Ma. Moreover, we observe frequent outliers towards higher ⁸⁷Sr/⁸⁶Sr ratios, which could be interpreted as the contribution of meteoric water to the brine, in-situ Rb decay, or post-depositional hydrothermal or diagenetic overprint. The combination of the ⁸⁷Sr/⁸⁶Sr data with mineral composition data of the samples suggests a contribution of meteoric water, probably river water, to the Zechstein Sea as the main reason for the observed outliers. Modelling the amounts of sea water and meteoric water in the brine indicates that 83‒99% of meteoric water would be necessary to explain the highest ⁸⁷Sr/⁸⁶Sr ratios observed in the Werra Formation.

The number of zircon age studies being published from all regions of the planet is consistently growing, as is for continental or global zircon ages databases. Unfortunately, a considerable amount of such data is often not utilized for future studies after their publication. Consequently, there is a considerable amount of valuable data that is waiting to be discovered for further use that could reach much further than reconstructing supercontinent cycles. An initial compilation of pre-Mesozoic zircon age data (N>5000, n>275000) characterizes the circum-Atlantic (s.l.) zircon provinces. Despite having compiled an initial zircon age database, further effort is necessary to reach the required sample density for mapping the age spectra of (meta)igneous host rocks and primary sediment flux in appropriate statistical, spatial and temporal frameworks. Nonetheless, this is a primary goal that will allow for more precise palaeogeographic reconstructions of terrane configurations in conjunction with additional data. To date, the zircon age database permits the identification of the primary zircon provinces and some sub-provinces at a reasonable terrane-scale resolution. The database also identifies distinct zircon age populations that can be used as "unique identifiers", e.g. to distinguish the western and the eastern parts of Cadomia or the role of the Kunene Intrusive Complex in southern Africa. Additionally, the presented compilation outlines the key zircon age provinces in large parts of the circum-Atlantic. Therefore, this study aims to present an initial impression of typical zircon age patterns found in the aforementioned areas at certain periods of time.

In Saxothuringia, widespread magmatic activity occurred from Mid Carboniferous time until Permian. Mid-Carboniferous magmatic activity resulted in pluton generation, exclusively, while the earliest volcanites are documented beginning in the late Carboniferous in intra-montane basins and in the Eastern Erzgebirge region. Volcanism started to dominate the magmatic activity during Carboniferous-Permian transition. Recently, several high-precision CA-ID-TIMS zircon ages allow to reconstruct the sequence of magmatic activity for the Western Erzgebirge (Tichomirowa et al., 2019), for the Eastern Erzgebirge (Tichomirowa et al., 2022) and for several intramontane bassins (Thuringian Forest basin – Lützner et al., 2020; Chemnitz and Döhlen basins – Käßner et al., in prep). These new high precision data allow a better understanding of the sequence of magmatic activity in general as well as the temporal relationships of special volcano-sedimentary formations.

Zircons (Zr[SiO₄]) are minerals that crystallize out of the melt at an early stage, primarily in felsic and intermediate magmatites. They are characterised by their particular resistance to mechanical and chemical influences and are therefore preserved for a long time in sediments that emerge from such magmatites. Besides their U-Pb age determination, studies regarding their morphological features help to improve provenance studies. Since different areas of origin of sediments are usually delimited by different age populations of the zircons depending on the geological evolutionary histories, areas of origin can be reconstructed by dating the zircons in the sediments. A sediment is therefore virtually the last link in a possible chain of geomorphological cascades. This so-called provenance research is a standard method in geology today, but is still rarely used in Quaternary research. In addition to the dating and thus assignment to a supply area, features on the grain surfaces of the zircons can provide information on the geomorphological transport mechanisms, an approach that is only slowly finding its way into research.
The aim of the lecture is to demonstrate the potential of provenance analysis and, in particular, surface morphological methods for Quaternary geomorphological questions using examples from the south-west of the USA.

Seasonality and extreme weather events are key aspects of past, present and future climate systems. Few climate archives preserve long enough continuous time series in sufficiently high temporal resolution to analyse (sub-)seasonal aspects of past climates. (Sub)tropical marine giant clams (Tridacna) are fast growing (mm-cm/year) and long lived (up to 100 years) organisms which build large aragonitic shells (up to 1m). Therefore, their shells are ideally suited to evaluate seasonality and extreme weather events in (sub-)tropical reefs, ever since their emergence in the early Miocene. Here we present a Miocene multiproxy palaeoenvironmental record from the Indo-Pacific region, specifically the Makassar Strait (East Borneo), spanning over 50 years. The temporal resolution of the oxygen and carbon isotope record is sub-monthly to seasonal, while it is sub-daily for elemental ratios (X/Ca; X=B, Na, Mg, Sr, Ba). The internal age model was determined using Daydacna, our recently developed Python script that uses wavelet transformation of measured daily elemental cycles to quantify growth rates within the shell (Arndt et al. 2023; G-cubed). This established a 57 years long growth duration. The seasonal patterns of the proxies measured in the fossil clam suggest that the Miocene reef was affected by precipitation and discharge dominated seasonality, affecting the availability of light and nutrients throughout the year. Extreme peaks in elemental ratios occurring together with structural changes in the shell could indicate extreme weather events.

Annual lake sediments are excellent high-resolution archives for reconstructing historical pollution. Usually, pollution reconstructions date back to the beginning of industrialization in the early 19^th century. Here, we present a long-term record form Lake Stadtsee located in the city of Bad Waldsee. Using historical written documents, the history of pollution can be linked to the economic activities in the city. In an absolutely dated sediment core we explored the concentration and composition patterns of Polycyclic Aromatic Hydrocarbons (PAHs) and heavy metals together with macro charcoal record at 1 cm steps.

First findings indicate that PAHs were primarily derived from pyrogenic, rather than petrogenic sources throughout the entire time interval. These most probably correspond to urban fire or domestic heating. The general trend observed by using PAH diagnostic ratios, is that the sources have shifted from low temperature pre-industrial combustion processes towards high temperature combustion processes in more recent times. Macro charcoal analysis revealed two main phases of biomass burning, which were separated by a fire free interval for more than 200 years. The first phase in the late Medieval period (653−533 cal BP), shows high proportions of burned grass and monocot leaves, whereas in the second phase in the early Modern Times (313 cal BP until today) wood was the main fire fuel. The molecular ratio pattern of specific methylated-phenanthrene isomers also indicates a change of fuel sources. Heavy metal analyses are currently being conducted. We expect chemical signatures of historical town main crafts (tanneries, smithies, textile bleaching).

The globally warm Miocene epoch is considered a model case for the near future climate. In view of the current coral reef crisis, studies on Miocene reefs can contribute to predictions regarding the stress resilience of today's reefs against global warming.

Here, we present stable isotope (δ¹⁸O, δ¹³C) and biomineralization (annual extension rate, skeletal density, annual calcification rate) records of massive reef corals of Upper Oligocene to Middle Miocene age (28 – 15 Ma) from the Aquitanian Basin (SW-France). The Aquitaine Basin formed a large, shallow-marine embayment of the North Atlantic at a paleolatitude of ~40°N, making this one of the northernmost reef coral environments at that time.

We find very low extension rates, typically indicative of low sea surface temperatures (SSTs), which are consistent with a habitat at the outer margin of the Oligocene-Miocene reef belt, but contradicting with measured low bulk densities, typically indicative of warm SSTs. According to clearly expressed annual δ¹⁸O and δ¹³C cycles, maximum skeletal growth and zooxanthellate photosynthesis occurred in winter – not in summer. This is surprising, since modern high-latitude reef corals preferentially grow in summer due to critically small radiation doses for zooxanthellae photosynthesis in winter. As published Miocene TEX₈₆-based SST reconstructions are critically high for reef corals, we currently test the hypothesis that high SSTs in summer were more limiting to reef coral growth than a low dose of photosynthetically available radiation in winter. Our findings tentatively suggest mid-latitudes may indeed represent refugia for reef corals in a warmer world.

Beginning in 1876 when Alfred Russel Wallace speculated on the biogeography of major mammalian groups in his seminal work, “The Distribution of Animals, with a study of the Earth’s Surface”, biogeographers have noted that the major groups of terrestrial mammals originated in the Northern Hemisphere and dispersed south. These dispersals supposed took place in the Mesozoic. With preponderance of relevant fossils in the Northern Hemisphere during that era and few from Gondwana, this hypothesis was strengthened with the collection of additional specimens over the last 150 years.

A handful of fossils discovered in the Southern Hemisphere during the past quarter century, indicate caution. Early Jurassic Argentine fossils of stem therians occur 50 million years earlier than undoubted therians (marsupials/placentals) in the Northern Hemisphere. Cimolodontan multituberculates are the most common Late Cretaceous mammals in the Northern Hemisphere, persisting until the Eocene. The oldest cimolodontan occurs in the late Early Cretaceous of Australia {two lower jaw fragments}, about 8 million years prior to appearance in the Northern Hemisphere.

Dispersal between South and North America was likely across the Panamanian region. From Australia to Asia dispersal may have been by island hopping as Australia was much further south in the late Mesozoic than at present.

Whether less than a dozen fossils is a harbinger of a replacement of a well-established biogeographic hypothesis will only be known when further specimens in the Southern Hemisphere come to light.

Scleractinian reef corals are excellent climate archives, frequently used for paleoclimate and paleoenvironment reconstructions. Reef corals capture environmental signals during the growth of their aragonite skeleton and can therefore record local variations in sea surface temperature (SST), light availability and water chemistry over decades. Thus, fossil corals hold a unique potential to provide insights into past climate. However, the application of ancient corals requires a careful assessment of the preservation state of their aragonite skeleton to identify diagenetic effects in proxy data.

Here, we present sub-annually resolved sclerochronologies of coral calcification and geochemical proxy data of zooxanthellate corals (Astreopora sp.) from the Eocene Greenhouse (Bartonian, 40 Ma) in northwestern France (Paris Basin) to investigate variable calcification responses to growth site specific environmental conditions. During the Bartonian, the Paris Basin embayment was located at a paleolatitude of about 45°N, which marks the northernmost range limit for reef coral growth in the Cenozoic era. Our results indicate that the corals were subjected to increased environmental stress, which is reflected in overall low skeletal growth rates (1.3 ± 0.6 mm/year, n = 15), the frequent occurrence of lesions and high density stress bands in the coral skeletal structure as well as ambiguous cycles of temperature sensitive geochemical proxy data.

This study provides implications on the adaption of calcifying organisms to unfavorable growth conditions including high seasonal contrasts (SST variability and light availability) and critical ocean water chemistry (freshwater inputs, evaporation, and seawater carbonate chemistry affecting Ω_arag).

Reconstructing the climate of the past requires archives that bear proxy information on temperature, precipitation, or atmospheric composition, for example. In this study we use contour marks as potential water level marks in mud sediments to reconstruct local evaporation rates at the Bromacker lagerstaette site in the Early Permian. The measured values indicate a daily evaporation of 1.5–3.75 mm with a median value of 2.25 mm/day. The calculated evaporation rates are compared with modern ones to estimating moisture, precipitation and seasonal climate. For evaluating reconstructed precipitation and evapotranspiration rates, values simulated by global climate models and calculated from geochemical datasets are furthermore incorporated. For the first time, quantitative data and models elucidate the climate of the Tambach Formation and Bromacker lagerstaette against the background of the pivotal transition from the Carboniferous Ice House to the Permian Hothouse climate. Our results suggest a strongly seasonal climate with wet summers and dry winters in a mountainous region based on unexpectedly low temperatures (10.9-15.0°C) considering the palaeo-location of the site in the tropical belt during the Early Permian. According to the modern vegetation model by Holdridge a moist forest biome is suggested for the Bromacker lagerstaette.

Voluminous pyroclastics are known to be formed in catastrophic caldera-forming eruptions. The reconstruction of the magma’s origin and lithospheric evolution beneath such calderas is still a challenging task in igneous petrology and volcanology. Probably one of the most interesting areas for studying volcanic activities is the Late Paleozoic of central Europe. Here, the deeply eroded Tharandt Caldera of the eastern Erzgebirge is one of the oldest volcanic edifices, comprising two crystal-rich rhyolitic ignimbrites, a vitrophyre, and microgranites.

In the present study, the pyroclastic record is characterized using a multifarious approach including whole-rock and µ-XRF analyses on fiamme, as well as electron microprobe data of glass and phenocrysts. Based on the results, the pyroclastic sheet within the caldera distinguished two rhyolitic ignimbrite units, the Lips Tullian and Mohorn members. The densely welded Mohorn member (welding degree VI) includes a vitrophyre, which can be interpreted as a rheomorphic diapir.

Thermometry of the ignimbritic members yield crystallization at 835 to 840°C for K-feldspar, apatite at 900 to 920°C, and zircon at 765°C to 800°C. It should be noted that the low zircon saturation temperature of 755°C in the vitrophyre shows that the agglutination and rheomorphism processes occurred in a short period during the eruption. The applied barometers unravel magma bodies in different lithospheric levels: an upper crustal magma body (5 to 10 km, P_Qtz = 1.2 to 3 kbar), a middle crustal magma body (20 km, P_Qtz = 5.6 kbar), and a lower crustal magma body (30 km, P_Qtz = 9 kbar).

Zircon megacrysts of gemstone quality hosted at different localities within the Lusatian Volcanic Field. Here two of them, the scoria cone of the basanitic Hofeberg volcano and an alluvial placer Hirschbörnel Creek downstream of the Buchberg trachyte dome, were dated and chemically analysed. The genetic interpretation within their geological context results in two different genetic models: In case of the first locality entrainment of the zircon with primary intergrowth phases in a basanitic melt resulted not only in resorption and reaction zones in the enclosing melt but in recrystallization of the zircon and its intergrown phases. In case of the placer locality the zircon crystals are unresorbed and can be deduced to have been derived from the initial explosive eruption of the highly evolved cupola of the trachytic melt system that is documented by the Buchberg trachytic dome being located upstream. Both, the U/Pb ages and the Hf isotopy of the zircon grains 28.2 ± 1.8 to 32.2 ± 2 Ma and εHf +3.1 to +6.8, respectively, correspond with those of the zircon host rocks. This implicates a cogenetic origin and a complex magma feeding system below the two monogenetic volcanoes.

The Lusatian Volcanic Field (LVF) is part of the Central European Volcanic Province, exhibiting magmatic compositions that manifest an alkaline trend, spanning from olivine nephelinites and basanites over trachytes to phonolites typical for intraplate settings.The volcanic field covers an area of about 6,000 km² and is situated in the border triangle between Poland, the Czech Republic and Germany. It represents the northeastern margin of the Ohře/Eger Graben (OEG). More than 1,000 volcanic structures associated with approximately 500 to 600 vents have been located within the LVF. Residuals of scoria cones, lava lakes, lava flows and maar-diatreme fillings occur in situ near the level of the original pre-volcanic terrain. Evolved rocks occur as monogenetic domes or intrusions in diatremes, while their volcaniclastic equivalents are rarely observed. In the center of the volcanic field, a central volcano is assumed which is proved by widely distributed tephra and a large variety of different volcanic lithologies. Parasitical smaller volcanoes are situated on the so-called Lusatian Central Volcano. The volcanic center of LVF occurs within the graben (OEG) structure. Based on recently determined eruption ages spanning from 32.9 to 29.3 Ma by ⁴⁰Ar/³⁹Ar dating, it has been established that the Lusatian Central Volcano remained active for a considerable period of 3.6 million years. This duration corresponds to the temporal emphasis observed throughout the entire volcanic field.

Located in the eastern part of the High Atlas Mountains, the Upper Jurassic-Lower Cretaceous magmatic complexes intrude predominantly along the thick Mesozoic sedimentary anticlinal ridge and within the Mouguer-El’Bour Paleozoic inlier. They are range in composition from mafic to felsic, including gabbro, diorite, and syenite.
Petrography admits that these intrusions show three types of gabbro as mafic facies: ordinary, biotite-bearing, olivine-bearing Gabbro as for the intermediate term diorite then the syenite.
Ordinary and biotite-bearing Gabbro are mostly coarse-grained and composed mainly of euhedral plagioclase, clinopyroxene, Biotite, alteration minerals including amphiboles, chlorite, sericite, and epidote, secondary minerals like apatite, sphene and opaque minerals included in the biotite grains. As for the olivine bearing Gabbro, olivine euhedral minerals are abundant with serpentinization faces mainly in the cracks these facies are exclusively found in the Tazmamart intrusion. Diorite is the intermediate facies it mainly comprises plagioclase, clinopyroxene, amphiboles, opaque minerals, and apatite. The syenites comprise aphanitic to phaneritic textures with both potassic, plagioclase feldspar and quartz which combined in a mermekitic texture, amphiboles, opaque minerals, apatite, and sphene.
Previous geochemical studies reveal a trend from mafic to felsic rocks, with transitional to alkaline affinities. These studies indicate a heterogeneous mantle source. Several researchers suggest that these magmatic intrusions occurred during the late Jurassic to Cretaceous period, which coincides with the closure of ocean basins and the final phase of continental plate collision.
We attempt to undertake mineral geochemistry in order to gain additional insight on magmatic process and the origin of these intrusions.

Im Untersuchungsgebiet NW-Böhmen / Vogtland treten an mehr als 300 Lokationen juvenile Fluide an Mineralquellen oder Mofetten aus, hauptsächlich von CO₂ magmatischen Ursprungs. Anomal hohe Mantelheliumanteile sind ein weiteres Zeugnis der im oberen Mantel zu suchenden Fluid-/Magmenreservoire. Die zahlreich bekannten sowie einige neu entdeckte Basaltstrukturen bekräftigen die Hypothese, dass es einen lateralen Zusammenhang zwischen den ehemaligen Vulkanschloten (Diatreme, Dikes) und den CO₂-Entgasungsstellen gibt. Unsere Untersuchungen bestätigen die bereits vor ca. 80 Jahren geäußerte Vermutung, dass die Vielzahl der magmatischen Eruptionen seit dem späten Oligozän mit den dabei geschaffenen tektonischen Strukturen die wichtigste Grundlage für die Ausbildung von rezenten Migrationspfaden für die Entgasung darstellen. Eine besondere Rolle für die Kontinuität der rezenten Entgasung spielt dabei aber auch das regionale Spannungsfeld und die seismische Aktivität, speziell der lokalen Schwarmbeben.

The Late Paleozoic North Saxon Volcanic Complex, situated east of the city Leipzig (Germany) hosts two nested caldera systems: the Rochlitz (RVS) and the slightly younger Wurzen Volcanic System (WVS). In addition to the voluminous Wurzen caldera fill ignimbrite, the WVS also comprises small-volume precursor eruptions (e.g. Cannewitz ignimbrite), whose classification as a post-climactic eruption of the RVS or as an initial eruption of the WVS remains uncertain. This study includes modal and geochemical investigations along an almost completely cored 648 m long profile through the deposits of the WVS at Großsteinberg (Grimma, Saxony). The observed depth-dependent and continuous changes in modal composition and geochemistry within the caldera ignimbrite facies suggest a close genetic relationship between the Cannewitz and the Wurzen ignimbrites. We, therefore, propose the new name Cannewitz member to emphasise the affiliation to the WVS. Characterised by a rhyolitic composition and low crystallinity (ca. 30.9 vol%), the Cannewitz member represents the initial eruption of the WVS from a rhyolitic cap of the magma chamber. During the continuous volcanic activity, the transition to the crystal-rich (up to 50.4 vol%) monotonous intermediate Wurzen ignimbrite, fed by a voluminous trachydacitic magma chamber, occurred. Based on the newly established minimum thickness of the caldera filling in the drilling, the erupted minimum volume could be recalculated to 838 km³. The resulting volcanic explosivity index of 7 qualifies the WVS as a supereruption.

The Athesian Volcanic District offers important insights into how volcanic activity influenced ecosystems during the Cisuralian, particularly at low latitudes, thanks to sedimentary successions intercalated with the volcanic units. By combining sedimentological, paleobotanical, palynofacies, qualitative and quantitative palynological, and stable carbon isotope studies, we reconstructed the depositional environments and vegetation dynamics across two distinct successions. The two studied sections reflect different depositional environments: one proximal and one more distal with respect to the margin of the lake and the source of the organic material. Pollen assemblages and plant fossils reconstruct a flora dominated by xeromorphic and xeromorphic-hygromorphic taxa, such as conifers (Collia, Feysia, Hermitia), seed ferns (Lodevia, Peltaspermum, Sphenopteris), and ginkgophytes (Sphenobaiera). Hygromorphic elements like lycophytes and ferns are rare but more abundant in the marginal succession of the lakes. The δ¹³C_org values are comparable with those of other Cisuralian continental successions, but a small variability is observed that correlates with the abundance of xeromorphic elements. This multidisciplinary approach suggests that one or more water bodies existed in a megacaldera setting, with water depth influenced by the palaeotopography. The climate was semiarid to arid, typical of the Cisuralian at low latitudes. The differences observed in the successions are not linked to climate shifts but to deposition of plant micro- and macroremains under different environmental conditions and, thus, reflect a taphonomic and paleoenvironmental signal.

Remote sensing methods proven to be useful for monitoring earth surface changes and identifying new patterns. In this study, our focus is to identify features such as moffetes based on their morphological characteristics (small cone or crater shapes) and patterns of degassing around them and along the rift zone. Here, we investigated Hartousov, Bublak and Milhostov areas which are known for their seismic and degassing activities. We conducted close-range aerial mapping surveys using UAVs (Unmanned Aerial Vehicle) with cameras and LiDAR sensors on board. In order to map and detect degassing areas, we process the camera data using SfM (Structure from Motion) to generate very high resolution orthomosaics. Using this data we are able to develop an inventory of the visible, spectral and topographic expressions of the degassing sites in the Eger Rift. In this presentation we will summarize the techniques used and provide an overview into the different types of mofettes, some building up topographic highs and others developing crater-like structures. Results underline that a combination of multispectral and LiDAR-based data analysis can help us not only study the known areas but also detection of new areas of degassing and moffetes. We believe such systematic studies can be widely applied and help identifying mofettes and degassing sites elsewhere.

A comprehensive time-series of integrated chemical and textural data from products of the 2021 eruption on La Palma, Canary Islands, using scanning micro-XRF are presented. Within our data we observe critical changes in plumbing system dynamics, including a progressive shutting-down of deep magma supply, weeks before the eruption concluded. These data and our workflow demonstrate how near-real-time volcano petrology can now be delivered. Answering “what is happening now?” has long been the highest priority for volcanic observatories, and approaches with rapid and data-rich returns like geophysics, and less so gas geochemistry, are favoured. This is like listening to the heartbeat or smelling the breath of volcanoes respectively, which can indicate changes are occurring deep within the plumbing system. Yet with approximately 20% of the world’s increasing and interconnected population now living within a 100 km of an active volcano, answers to new questions are being urgently demanded. To understand the driving mechanisms of melting, storage, crystalisation, volatile charging, ascent, and eruption of magma, comprehensive “blood tests” are needed which can help answer “what will happen next?” and “how long will it continue?”. This is shown to be possible with scanning micro-XRF. Moreover, geophysics and gas geochemistry cannot be used to look back into the past of a volcano, and so are faced with an unaddressable lack of empirical historical comparisons. Our study disproves the traditional view that petrology is too slow, too expensive, and too specialized to deploy in many volcano monitoring settings.

The geology at the margins of continental collision zones is characterized by a pronounced three-dimensionality, whereby crustal thickening, lateral material flow, and crust-mantle interaction are acting processes. The region of the eastern syntaxis of the Himalayas, parts of which are located in Myanmar, China, and India, is an ideal natural laboratory for studying the processes at the transition from continental collision to oceanic subduction. We report an investigation of the location of the continental collision‒oceanic subduction transition in the upper plate (see Min et al., 2022 for a study on the lower plate), the Mogok metamorphic belt, an equivalent to the Lhasa Terrane and the Gangdese magmatic arc in Tibet. Our working hypothesis is that crustal thickening by shortening, Barrovian metamorphism, anatectic melting characterize the continental collision section and arc magmatism, Buchanan metamorphism, and lack of major shortening characterize the oceanic subduction section. Therefore, we reconstruct the pressure-temperature-deformation time (P-T-d-t) history along several transects along-strike of the Mogok metamorphic belt from Yunnan in the north to the Mergui archipelago of southern Myanmar in the south. Transition zones from continental collision to oceanic subduction may also trigger the initiation and subsequent sideway propagation of slab break-off (e.g., Webb et al., 2017). Such a location may be characterized by advective heat input, manifested by ultra-high temperature metamorphism and a flare-up of magmatism. We present first results from several traverses concerning this research questions from petrology, and Lu/Hf garnet, U-Th-Pb zircon, monazite, titanite, Ar/Ar amphibole, mica, feldspar, fission-track zircon, titanite, and apatite, and (U-Th)/He apatite geochronology.

The Greek island of Nisyros, located in the Aegean Sea and part of the Cyclades Arc, is known for its hydrothermal alterations and phreatic explosions, forming the Stefanos crater. Sudden explosions, like the one in 1887, pose a significant hazard. The aim of this work is to identify and locate the various degrees of hydrothermal alteration with a combination of point-wise rock sampling and geospatial data analysis. For the petrological study different lithologies at different degrees of hydrothermal alteration are sampled and analyzed with the XRF. Geospatial analysis is realized by drones equipped with optical and thermal cameras. The data are processed and analyzed with Metashape and ArcMap software. Photogrammetric processing of the drone data allows generating orthomosaics of the Stefanos crater with a resolution of 2.94 cm/pix. The infrared data show an increased apparent temperature at the fumarole fields of up to 50°C. Using Principal Component Analysis (PCA), the geological units are classified in temporal lake (0), outer crater wall (1), upper crater wall (2), tuff layer (3), lower crater wall (4), sediments – divided into debris flow (5A) and crater ground (5B), a mixture of lower crater wall and fumarole crust (6) and fumarole crust (7). The degree of hydrothermal alteration increases from unit 0 to 7, with unit 7 being the most altered, covering an area of approximately 1.1e+4 m². The classification and XRF analysis are used to determine the relationship between temperature, distance to the crater center, sulfur content and degree of alteration of various lithologies.

The Late Cretaceous succession of the Münsterland Basin is up to 2,000 m thick and comprises mainly limestone, marlstone and chalk. As flooding came from the north, siliciclastic coastal sediments dominate along the southern margin. Several large limestone quarries in the area of Lengerich at the today´s northern basin margin give detailed insights into distal Early to Late Turonian deposits (Hiss et al. 2007). These marine sediments were uplifted, folded and overturned along the Osning Fault Zone. Wiese & Kaplan (2004) argued to use the good quality exposures as Global Boundary Stratotype Section and Point (GSSP).

The Dyckerhoff quarry near Lengerich-Hohne in the SW Teutoburg Forest show intercalations of thin marly limestone and marlstone beds of the Lengerich Formation, which is part of the Upper Plänerkalk Subgroup. A few altered tuff horizons (TD1, TC and TF) occur within the succession, which have REE pattern with distinct negative Eu anomaly implying a volcanic origin (Wray et al. 1996).

Although intensively bentonized, several idiomorphic zircon grains with high-T typologies (850-900°C) could be separated for radiometric age determinations from the TD1 layer in the basal Late Turonian strata. The zircon grains yield an U-Pb age of 91.5 ± 0.7 Ma, allowing correlations with tuff horizons found in Upper Cretaceous sediments in NW Europe (Wray 1999) or in the Polish Carpathians (Bąk et al. 2001). The new data may also help to identify the source area of these pyroclastic layers of supposed acidic composition.

One of the most tectonic active regions in central Europe is the Cheb Basin at the western margin of the Ohře/Eger Rift, which is characterized by earthquake swarms and spots of mantle-derived carbon dioxide exhalation (mofette, spring). This prompts the Geological Surveys of Bavaria and Saxony and their cooperation partners to detect suspected sites of gas exhalation in dry mofettes.

Digital elevation model-based geomorphic indices and color infrared image data were acquired to decipher fault systems and emphasize differences in vegetation. This led us to the finding of a ca. 20 km W-E-directed active fault system that extends from Selb-Reuth via Aš to Bad Brambach and finally borders the N-S-oriented Plesná-Počátky Fault. Throughout the fault zone, the conspicuity in the vegetation (circular cover of sedge and reed) points towards CO₂ gas exhalation.

Geophysical reconnaissance at the Brambach spar garden confirmed the presence of gas caverns at the contact between the Fichtelgebirge/Smrčiny Granite and the mica schist. First emission measurements at the Brambach Mofette Field yield flux rates of ca. 16340 mg/(m²*h). Although significantly lower than in the mofettes of the Soos swamp, our results confirm the occurrence of a dry mofette in Saxony.

The conchostracans (clam shrimp) are bivalved crustaceans that belong taxonomically to the branchiopod Diplostraca. Their chitinous carapace valves are often only some millimetres, or rarely view centimetres, in total length. Most records of fossil conchostracans have been made in fine-grained sediments that have been deposited under quiet water conditions in ponds or lakes. The fossil valves are preserved as imprints and casts in sediments, but their chitinous shell substance or its derivate can be preserved as well. In contrast, preservation of the conchostracan body parts are rare in the fossil record. For the present study, the literature of fossil conchostracans has been reviewed, in order to compile a listing of occurrences that bear fossilized soft parts of the conchostracan body. In result, more than 20 fossil occurrences of conchostracan “soft body” preservation were recorded. These examples are presented herein, based on the referenced literature.

The still active part of the Los Tuxtlas Volcanic Field (LTVF), is located between the eastern edge of the Trans-Mexican Volcanic Belt (TMVB) and the Central American Volcanic Belt (CAVA). The field stretches over 2400 square kilometers and includes ca 350 well preserved and another ca 200 less preserved volcanic edifices. In respect to phreatomagmatic eruptions, and thus related volcano-types, the LTVF is the most populated volcanic field in Mexico, and comparable to the densely maar-populated West-Eifel volcanic field in Germany with numbers around 70 to 90. Only 67 of these structures in the LTFV have been morphologically analyzed. About 21% of these contain a lake, while 70% are dry, and 9% are not maars but tuff cones. Only about 40% are simple structures, while the rest are either compound or complex.

The volcanic field, and hence the spatial distribution of its members is defined by a large NW-SE fault system, a compressional-strike slip regime and a central shield-like volcano. The high clustering of volcanoes in space together with the field evidence of contemporaneous emplacement of individual monogenetic volcanoes in form of compound (≥two volcanoes of the same kind, either maars or scoria cones) or complex systems (mixed scoria cone-maar constructs), together with morphological evidence shows that the monogenetic volcanoes are not only clustered in space, but also in time. Many of these volcano-clusters are only a few thousand years old. This fact, together with the abundance of phreatomagmatic eruptions in the field imply a considerable risk for the population.

The continental crust was formed predominantly by magmatism at subduction zones. Peaks in the age distribution of detrital zircons derived from the continental crust have been interpreted to indicate that the generation of new crust was a non-steady state process. Here we show that the composition and thickness of subduction zone crust, as well as arc lava compositions, are correlated with arc duration. Older, long-lived arcs have thicker crust than younger arcs, a higher proportion of zircon-bearing felsic middle-upper crust, and erupt lavas with higher (La/Yb)_N and Zr/Yb_6.0 ratios and Zr_6.0 values. The global average crustal thickening rate of active arc segments is 0.12 km/Myr, yielding a present-day global crustal growth rate at arcs of 0.71 – 0.87 km³/yr. Our observations provide a means to estimate the longevity of extinct arc segments from the incompatible trace element ratios of their lavas. Since long-lived arcs with a thick felsic crust component contain a higher proportion of zircon-bearing felsic rocks, and are more resistant to destruction by subduction, variations in the average lifetime of arcs over Earth’s history will influence the detrital zircon record. We propose that the long-lived arcs associated with supercontinents may explain the peaks in detrital zircon age distributions.

Catastrophic lava dome collapse is considered an unpredictable volcanic hazard because the physical properties, stress conditions, and internal structure of lava domes are not well understood. To better explain the locations of recent dome instability events at Merapi volcano, Indonesia, we combined geochemical and mineralogical analyses, rock physical property measurements, drone-based photogrammetry, and numerical modelling. We show that a linear fissure and a horseshoe-shaped alteration zone that formed in 2014 was buried by lava extrusion in 2018. The linear fissure controlled the location of the new lava dome, while the horseshoe shaped zone influenced subsequent instability. Geomechanical, mineralogical, and geochemical data suggest that such alteration zones are characterised by mechanically weak, hydrothermally altered materials, and we show that the new lava dome is collapsing along this now-hidden horseshoe shaped and comparatively weak alteration zone. To derive an improved general understanding of this phenomenon, we then combined recent laboratory data for the mechanical behavior of dome rocks with discrete element method models to show that the presence of weak zones within lava domes increases instability, which is exacerbated when the size of the zone increases or when the zone is positioned off-centre. Our results highlight that improved understanding of dome architecture and compositional variations due to hydrothermal alteration within domes is essential for assessing hazards associated with dome and edifice failure at volcanoes worldwide.

The Late Palaeozoic continental rift system in Central Europe was the cause of pronounced magmatic activity, which led to the intrusion of numerous plutonic and subvolcanic bodies and voluminous pyroclastic deposits in numerous calderas. In particular, the petrogenetic evolution of magmatic systems provides an interesting field of research due to the heterogeneous composition of the basement. Hence, geothermometers are an important analytical tool for understanding such petrogenetic evolution and are used to determine the formation temperature of the post-orogenic igneous suite between the Altmark (Saxony-Anhalt) and the granulite massif (Saxony).

Calculated saturation temperatures of zircon and apatite from igneous rocks of the Central European Extension Province of the present study show two significant trends. The comparison of the saturation temperature values of zircon (T_Zrn) and apatite (T_Ap) from rocks of well-known Cenozoic deposits of the Basin and Range Province in the southwestern United States with that of the Central European Extension Province suggests that large differences between the saturation-temperature values (T_Ap >> T_Zrn) indicate a zoned magma chamber, while saturation-temperature values close to each other (T_Ap ≥ T_Zrn) indicate magma mixing.

The DFG-funded project Chatseis (BU3894/3-1, KO6375/2-1) intends to combine high-resolution seismic reflection imaging and full waveform inversion (FWI) for better understanding of overdeepened valleys. By combining both methods, we expect an improvement in resolution, accuracy, and reliability of the data analysis. To develop our workflow and answer scientific questions regarding the ICDP project Drilling Overdeepened Alpine Valleys, we record seismic datasets at ICDP sites 5068_3 (Schäftlarn, GER) and 5068_5 (Bad Aussee, AUT).

At Schäftlarn, about 30 km south of the city of Munich, we acquired three high-resolution P-wave profiles with various receivers (Burschil, 2024). Seismic sources are the 4 t hydraulic vertical mini-vibrator MHV4P, vertical and horizontal wheelbarrow-size ELVIS vibrators, and 26 explosions of 1 kg, conducted by the LfU.

Preliminary results show the structure of the valley, which are in accordance with the interpretation of the ICDP drill core. Reflections from the valley base are caused by the strong impedance contrasts of Quaternary sediments and Molasse bedrock. Basin internal reflections mark the boundary between gravels and glacial sediments. A first arrival traveltime tomography (FATT) of the explosive source data was performed as preparation for the FWI. The FATT velocity distribution shows high velocities for the gravel units and decreasing velocity towards north. Reflection image and velocity distribution are in good agreement.

The seismic campaign at Bad Aussee is scheduled for June 2024.

Burschil 2024. Seismic measurements, Project Chatseis. BGR Survey report. doi:10.25928/pet1-6838

The sea floor drill rig MARUM-MeBo70 was deployed in summer 2023 in order to install observatories for the investigation of hydrothermal circulation in young oceanic crust. The expedition went to the southernmost tip of Reykjanes Ridge – a part of the Mid-Atlantic Ridge. We were able to set two pairs of observatories in 1500 and 1700 m water depth, respectively. At each site two holes with 103 mm diameter were drilled through a 5 to 30 m and an additional 5 to 13 m into the underlying ocean crust. The drill string was lifted by one drill pipe before a last prepared rod – the observatory rod - was screwed onto the drill string. The observatory rod sealed the drill pipe from sea water and was equipped with temperature sensors. One type – the injection observatory – also contained a system for releasing a tracer to the base of the borehole where it has contact to the fluid circulation system within the upper ocean crust. The second type – the monitoring observatory – was installed in a distance of a few tens of meters and contained an additional osmo sampler for sampling the fluids from the upper crustal aquifer the base of the bore hole. The osmo-samplers will be recovered during an upcoming expedition in late summer 2025. This experiment will help to better understand the relevance of hydrothermal circulation in the flanks of ocean ridges for the exchange of elements and heat between the ocean crust and the oceans.

The chemical composition of magmatic sulphides can be used to comprehend the chalcophile element fractionation processes in magmatic systems that reached sulphide saturation [1-2]. We performed LA-ICP-MS analyses of sulphides hosted by gabbros of the Pacific (ODP147), Indian (ODP176, ODP179, IODP360), and Atlantic (OPD209 and IODP305) spreading centres, as well as from the Raoul Island and Troodos Ophiolite. Our results show that most gabbros contain large magmatic sulphides (mostly above 100 m to 1 mm). These sulphides can be classified as former sulphide liquids that crystallised as Fe- and Ni-rich monosulphide solid solutions, mainly consisting of pyrrhotite, and Cu-rich intermediate solid solutions. A few sulphides found in the Mid-Atlantic Ridge and South West Indian Ridge show lower Cu contents and consist only of monosulphide solid solutions.

Interestingly, sulphides of the Troodos Ophiolite and Hess Deep (Pacific Ocean) show a large variation in Ni and Ni/Cu ratios. We believe this indicates that these magma reservoirs possibly experienced an onset and offset of sulphide saturation, reflected by different Ni content. Furthermore, particular elements with intermediate solid solution affinity, including Cu, Se, Ag, Sb, Au, Te, and Bi, show a higher content in arc and the Pacific sulphides. This indicates that the initial Cu content of a magmatic system strongly influences the chalcophile element content of magmatic sulphide droplets.

[1] Wood, B. J. and Kiseeva, E. S. (2015), Earth and Planetary Science Letters, 424, 280-294. [2] Patten, C. et al. (2013), Chemical Geology, 358, 170–188.

The Late Miocene Cooling (LCM) has been recognized as a global event in the climate record, and the start of modern ecosystems between 7.0 - 5.5 Ma occur globally; little is known about changes in aquatic ecosystems especially shallow water carbonate ecosystems, such as coral reefs, where few good proxy records exist. A “reef gap” existed during the Pliocene in the area of the Central Indo-Pacific, where reefs that had been present during the Messinian (7 - 5 Ma) drowned by the Early Pliocene (5 - 3 Ma). Here, we present a TEX₈₆^H-based sea surface temperature (SST) record for the Coral Sea, suggesting that the LMC was more pronounced in the Central Indo-Pacific than previously thought. During the LMC, the SSTs at ODP Site 811 declined by about 2-3ºC, and cooling lasted from 7 Ma to possibly as late as 5 Ma. Therefore, the timing of this event is the same as the “Pliocene reef gap.” The timing of the onset of this event matches the cooling in the records. This suggests that the LMC was a final stressor that provided a regional driver for the collapse of reefs and, therefore, a potential cause for the “Pliocene Coral Gap.” The relatively rapid and intense change in SST and other stressors associated with the cooling caused coral reef systems to collapse across the Central Indo-Pacific.

Continuous mapping of drill cores in the sub-mm range with µ Energy dispersive x-ray fluorescence (EDXRF), laser induced breakdown spectroscopy (LIBS) and hyperspectral imaging (HSI) can provide chemical, mineralogical and textural information in such a detail, that systematic larger scale textural changes and mineral chemical repetitions can be recognized bringing new aspects into debate. We investigated three magnetite horizons from drill core BH7772, Marula Mine, Eastern Lobe crossing the Upper Zone of the layered Bushveld Igneous Complex. The three methods applied provide information at different pixel size 20/40µm for EDXRF, 75µm for LIBS, and for HSI 150µm, 400µm, and 400µm for VNIR; SWIR and LWIR were recorded. Whilst µEDXRF and LIBS provide a grid of identical pixel sizes based on step by step or on the fly data acquisition, HSI uses a linear detector generating optically distorted pixels. Therefore co-registration becomes problematic for small grains and in peripheral zones. Additionally LWIR pixels show blur effects since information of a shown 400µm pixel integrates approx. 1mm² area, adding spectral features of neighbor phases. We used a first supervised classification of phases for both µEDXRF and LIBS by ENVI software and spectral angle mapper algorithm. Selected phases were used as masks to obtain LWIR spectral changes due to mineral orientation. Larger monomineralic areas provide good grain size information, whilst small areas are influenced by other phases. Beside this problem, grain sizes can be obtained without using thin sections.

We present a new high-resolution XRF dataset offshore Africa in the equatorial Atlantic to investigate elemental ratios reflecting e.g. terrigenous input and/or bioproductivity. The data will be analyzed cyclostratigraphically using spectral analysis, evolutionary approaches and correlation techniques. Special focus is placed on the Mid-Pleistocene transition (MPT) and the Mid-Brunhes Transition, two periods which are characterized by changes in the amplitude and frequency of glacial-interglacial variability.

Another focus of the cyclostratigraphic analyses is the sub-Milankovitch frequency domain. Half-precession (HP) signals (~9,000 - 12,000 years) are still poorly understood, despite their occurence in several African terrestrial records. One main goal is to characterize the evolution of the HP signal during the Mid-Pleistocene Transition (MPT) unitl present at sites 662 and 663. Since precession is modulated by eccentricity, a similar relationship can be assumed for HP and eccentricity. The newly spliced dataset and its submillennial resolution will provide a clearer insight into the presence, amplitude and role of HP during the Pleistocene.

The Mid-German Crystalline Zone (MGCZ) plays a key role to unravel the complex pre- to syn-Variscan tectono-magmatic evolution in central Europe from the Neoproterozoic to the late Carboniferous. The most complete record of this evolution is preserved in basement rocks of the Bergsträsser Odenwald, even though highly ambivalent. While a large number of (isotope)geochemical and geochronological data and geodynamic models exist for the Variscan evolution of the Bergsträsser Odenwald (between 360 and 320 Ma), information about pre-Variscan events is scarce, although lately published zircon ages constrain pieces of Cadomian basement and Silurian intrusiva. Our new results of zircon U-Pb dating confirm these findings and point to a widespread occurrence of pre-Variscan intrusive rocks in the Bergsträsser Odenwald, which are known so far in this extent only from the Böllstein Odenwald.

Detrital zircon grains reveal very different age spectra, suggesting a wide range of source areas and supply routes of the protoliths of the investigated metasedimentary rocks. Maximum depositional ages range from the Precambrian to the Variscan era and indicate that the Odenwald basement preserves different periods of a prolonged geodynamic evolution, much longer and complex than previously thought. Our new findings have consequences for the evolution of the MGCZ and adjacent areas within the Central European Variscides.

First phase of the GRIND project (Geological Research through Integrated Neoproterozoic Drilling) is focused on the Ediacaran-Cambrian Transition (GRIND-ECT) in southern Namibia. The drills are cored into Lower Kuibis and the Upper Schwarzrand subgroups. Both form part of the Nama Group. Within the mixed siliciclastic-carbonate succession several ash layers occur. According to U-Pb TIMS ages of ash layers such sequences were deposited in a timeframe of c. 555 to 538.35 Ma during the Late Ediacaran to the Early Cambrian. Six boreholes were drilled into the sedimentary sequence and cover most parts from the Kanies to the Spitskop members. Whole-rock geochemistry in selected sediments provide clues to show shifts in the plate tectonic setting, the palaeo-environment and the evolution of life. In this regard, major and trace element contents in both subgroups are generally higher than values suggested for the Upper Continental Crust, while varying with respect to the Post-Archaean Australian Shale. Ratios such as SiO₂/Al₂O₃, Al₂O₃/Na₂O or K₂O/Na₂O indicate slightly higher compositional maturity in the lower subgroup than in the upper one. Trace element ratios such as Th/Sc, La/Sc, Th/Sc, Cr/Th and La/Co indicate predominantly felsic sources. However, elements associated with mafic input such as Sc, Cr, Co are more abundant in the upper subgroup, while elements such as Zr and Hf, related to higher felsic elements from stable areas, are more frequent in the lower subgroup. Such key elements indicate a change of the tectonic evolution from a passive margin setting to a continental island arc scenario.

Great subduction earthquakes cause Coulomb stress changes that can trigger intense aftershock seismicity, including strong earthquakes in the upper plate. The Coulomb stress changes are commonly computed assuming that the regional stress field does not change in the earthquake and that gravity can be neglected. However, geophysical observations from great subduction earthquakes indicate that the regional stress field changes in the earthquake and that aftershock seismicity in the upper plate may be driven by gravity.

Here, we use finite-element models of force balance to evaluate upper-plate stress changes in great subduction earthquakes. We show that gravitational stresses greatly influence the Coulomb stress change in a megathrust earthquake and cause a dependence of the stress change on the pre-earthquake stress conditions. While the dependence on pre-earthquake stress conditions complicates the assessment of the Coulomb stress change, accounting for it provides important information on the factors controlling the aftershock seismicity in the upper plate. We discuss these aspects at the examples of the 2011 M9 Tohoku-Oki (Japan) and the 2010 M8.8 Maule (Chile) earthquakes.

The North Alpine Foreland Basin (NAFB), or Molasse Basin, represents the northern foredeep of the Alps. In southern Bavaria, geothermal exploration of the past two decades resulted in new seismic surveys and wells, and subsequently to a better understanding of the structural evolution of the central NAFB. Three main fault clusters can be distinguished: The most prominent (1) is trending East-West parallel to the orogenic front and the basin axis and is – so far – attributed to simple extension during basin formation. Less prominent are faults running Northwest-Southeast (2), located mainly around the intra‑basinal high of the Landshut‑Neuöttinger‑Hoch, a tectonic feature already existing since Permian times. Fault cluster (3) strikes Southwest-Northeast. We attribute the latter to Miocene orogenic processes in the Alps, in particular to the clogging of the subduction in the Eastern alps, which led to formation of the Adriatic indenter and subsequently to the uplift of the Tauern window and an eastward shift of the alpine nappes along Northeast-trending, sinistral strike-slip faults. Focal mechanisms indicate the same type of motion for fault set (3) within the NAFB. These faults therefore acted as shear zones between the Eastern NAFB with a clogged subduction in the Eastern Alps, and the Western NAFB, where southward subduction underneath the Western Alps persisted. The orogen parallel faults (1) of the eastern NAFB, so far only seen as being extensional, experienced a sinistral shear during the Miocene (like the nappes of the Eastern Alps), whose intensity was decreasing with increasing distance to the orogenic front.

The Bergell Pluton (BP) is a calc-alkaline intrusion located in the Italian Alps, north of the Insubrian Line. The intrusion continues into the Southern Steep Belt (SSB), an E-W-striking, north-block-up mylonite zone that affects the pluton and the underlying high-metamorphic nappe pile.

In the upper Valle dei Ratti, a large antiform (VRA) is exposed, which translates the base of the BP and the underlying gneisses into the SSB. We present a new geological map, structural field data and microstructural observations from this area. Petrological mapping reveals an alternating sequence of different gneisses and schists below the BP and metasedimentary and ultramafic rocks at its margins. Previous maps displayed the two limbs as derived from fundamentally different tectonic units below the pluton. Continuous metasedimentary layers, however, indicate a single basement unit. The VRA and associated small-scale folds show E-plunging fold axes and pronounced stretching parallel to fold-axes orientations. This stretching lineation is found in the entire area, also further north (Galli et al., 2013, doi:10.1007/s00015-013-0120-1), and is related to top-east shearing. In the study area, it continuously translates into the lineation associated with north-block-up, left-lateral shearing in the SSB. We propose that the shear zone of the SSB is folded together with the base of the BP and thus identical to right-lateral, south-block-up shearing at the northern border of the Gruf complex. This scheme would explain the metamorphic gap on both sides of the Gruf complex and why the SSB does not exist east of the BP.

In the vegetated German uplands many outcrops are temporary and the information they hold is easily lost. In fortunate cases, publications give insights into outcrops long since gone and provide the opportunity to reinterpret the old observations. I report the example of a roadcut created during construction along the A7 motorway near Göttingen in the 1950s. The geology exposed is documented as detailed line drawings in a paper (Wunderlich 1959). The main feature exposed was an arched, antiformal contact between Lower Jurassic shale above and Middle Triassic Muschelkalk limestone below it. The Muschelkalk beds beneath the contact are folded and truncated against it. In the south, the Jurassic strata are overlain by Muschelkalk and upper Buntsandstein. This seemingly chaotic arrangement was interpreted by Wunderlich (1959) as the effect of a landslide that had emplaced a jumble of Triassic blocks floating in Jurassic shale over Triassic bedrock. Kinematic modelling shows that the arched contact can be interpreted as an originally planar normal fault of > 1 km displacement that was later folded together with its footwall. Folding and the Triassic rocks overlying Jurassic in the south indicate reverse reactivation of the normal fault, but also a new thrust fault splaying from it. The major normal fault modified by later shortening matches the evolution of the adjacent Lower Saxony Basin with Late Jurassic to Early Cretaceous extension and Late Cretaceous inversion. The relatively low-angle normal fault may help explain a main feature of two short, nearby seismic lines acquired for research purposes.

In the Variscan Batholith of Corsica large-scale, variably trending magmatic flow patterns are developed with steep magmatic foliation. This pattern is intensified by magmatic layering, mainly km-long lenses and layers of mafic and intermediate intrusions in the granitoids. Fabrics on the macro- to micro-scale indicate magma mingling and mixing. This reflects the complex intrusion history and the compositional variability of the Corsica Batholith on various scales.

At Abbartello, north of Golfe de Valinco (southern Corsica) in an area of at least 100 km² diorite, tonalite and granite form alternating layers and lenses from several hundred meter down to millimeter thickness. Together with aligned platy feldspars, amphibole and biotite, these layers represent a flow foliation that results from several pulses of fragmentation, magma injection and mingling. Deformation of magma is indicated by boudinage, melt-injected micro shear zones, fragmenting and pseudo-folding with axial-plane parallel alignment of amphibole and biotite. The intensity of grain alignment roughly correlates with the thicknesses of layers. Weak sub-solidus deformation is indicated by chessboard subgrain patterns in magmatic quartz and by rare, up to 1 mm large, recrystallized plagioclase and amphibole grains.

Anisotropy and variable intensity of crystal alignment, together with melt-present fragmentation are interpreted as variations of flow intensity and strain-rate. The repeated injections of mafic to felsic magma and crystallization in the presence of a regional stress field reflect large-scale movements during late-Variscan crustal reorganization and represent an excellent example of localization of deformation into magma-enriched parts of the continental crust.

The western border of the Bohemian Massif is characterized by a complex pattern of major NW-SE striking fault zones which form the tectonic boundary to younger sedimentary rocks to the west. To date, data about orientations, kinematics and the spatial distribution of brittle faults across the Moldanubian basement is scarce.

In 2023, geological field mapping focusing on structural features was carried out in the Bavarian Forest between the Pfahl fault zone and the Czech-German border. A total of 1070 fault planes were measured in outcrops of late to post-Variscan magmatic rocks, metamorphic rocks of the Moldanubian sensu stricto as well as in metabasites of the Teplá-Barrandian unit. After reconstructing their hypothetical paleo-stress fields, a total of six different main stress regimes were derived, representing the plate tectonic evolution in central Europe from Carboniferous-Permian to recent times: (1) Late-Variscan NNW-SSE compression is characterized by a conjugate fault set (WNW-ESE, N-S) with abundant muscovite on slickensides. Most noteworthy, partial reactivation under today’s similar stress field is likely. (2) N-S trending normal faults represent E-W extension presumably during the Permian. (3) Sinistral reactivation of NW-SE striking faults and dextral activity on WSW-ENE faults can probably be assigned to a Permian event with E-W shortening. (4) Presumably Late Jurassic to Early Cretaceous NE-SW Extension activated NW-SE trending normal faults. (5) Late Cretaceous to Paleogene NE-SW compression led to extensive dextral reactivation of N-S to NNE-SSW striking faults and sinistral motion on ENE-WSW trending structures. (6) Cenozoic rifting caused normal motion along NE-SW striking faults.

The offshore flank of Kilauea volcano (Hawaii, USA) is mobile, experiencing both earthquakes and intermittent landslides. A basal décollement underlies the entire mobile flank on which seaward movement occurs due to the gravitational loading and lateral push of the magmatic plumbing system. The Hilina Slump rides on top of the mobile flank, and the structures bounding the Hilina Slump activate concurrently with large earthquakes. The Midslope Basin is also located on the mobile flank northeast of the Hilina Slump and was likely formed by an ancient landslide, whereas the easternmost part of the mobile flank appears to be unaffected by landslide activity. We created two-dimensional finite-element models to understand why the Hilina Slump formed in its present location and why the eastern part of the mobile flank remains intact. The preliminary results show that movement of the mobile flank along the basal décollement leads to the formation of shear zones within the flank, suggesting that the Hilina Slump formed in response to long-term flank mobility. The implications for the current stability of the Hilina Slump are subject of further investigations. Ongoing research will include direct shear experiments on samples collected from the submarine flank of Kilauea to investigate the mechanical properties of the mobile flank and inform the finite-element models.

The western part of the Vordere Bayerische Wald (WVBW) forms the south-western part of the Bohemian Massif. Mainly it consists of metamorphic units of the Moldanubicum sensu stricto which were intruded by late-Variscan granitoids such as the Metten or Regensburger Wald Plutons. To the west and north-west, post-Variscan units are incised by the Regen river.

The dominant tectonic structures are the (W)NW-(E)SE striking Pfahl fault and Danube fault. Smaller fault systems occur parallel to these. They are locally dissected by NNE-SSW trending faults, such forming a mosaic of smaller blocks. Major NNW-SSE trending faults, e.g. the Keilberg fault, which marks the western boundary of the basement against Mesozoic and Cenozoic strata of the South German basin.

Extensive structural data were collected in the WVBW in order to capture the fault inventory beyond the main fault zones. Based on 428 fault measurements with kinematic indicators, eight palaeo-stress fields could be identified: 1) (N)NW-(S)SE compression; 2) NE-SW compression; 3) E-W compression; 4) N-S compression, 5) NW-SE extension; 6) NE-SW extension; 7) E-W extension; 8) N-S extension.

With exception of the probably Permian E-W compressive regime, the temporal assignment of the stress fields shows that older, presumably late-Variscan structures were repeatedly reactivated. Thus, it is highly probable that under the present stress field (+/- NW-SE) older, mainly N-S striking faults were reactivated. A conjugate set of NE-SW and NW-SE striking faults formed under N-S compression could also be reactivated by today’s similar stress field north of the Alps.

The Bavarian Pfahl Zone represents a late Variscan, NW-SE striking, transpressive shear zone intruded by large volumes of syn- to post-kinematic felsic plutonites. In this setting, we investigate the relationship between anisotropic plutonic fabrics and the regional tectonic setting for a series of granite intrusions. We combine the analysis of crystallographic preferred orientation (CPO) and shape preferred orientation (SPO) of rock-forming minerals with the orientation of microfractures. Large-area electron backscatter diffraction (EBSD) is used to analyze the CPO and SPO of the main mineral phases. The orientation of open and healed microfracture sets is determined by U-stage measurements. Early healed microfractures recorded by secondary fluid inclusion traces are interpreted to result from hydraulic fracturing in a deviatoric stress field. Samples show up to two orthogonal fracture sets per sample, explained by the orientation of σ2 and σ3 shortly after crystallization. Quartz indicates common, weak, but distinct, rhomb-dominated CPOs for all samples. With respect to the geographic reference frame, three orthogonal rhomb maxima are independent of magmatic flow fabrics, but correlate with the orientation of healed microfracture sets. We interpret these CPOs as the result of stress-induced Dauphiné twinning. Furthermore, we discuss the common spatial relationship of quartz rhomb distributions and healed microfractures on the late- to post-magmatic stress field of felsic plutonites.

We present petrological data and seven Lu-Hf garnet–amphibole–whole rock ages obtained from a single garnet-hornblende-mica schist sample from the Isua supracrustal belt (West Greenland). Garnets grew during prograde metamorphism toward regional amphibolite-facies peak conditions, and a mylonitic foliation formed during and after garnet formation. Garnet crystals show typical prograde zoning with no visible traces of a relict garnet generation. They do show various degrees of retrogression. While some crystals are perfectly euhedral with only minor chemical alteration along cracks, others are elongated in the foliation and either grew in this shape or were deformed. Some grains have disintegrated into clusters of resorbed smaller ones. Six garnet splits were separated from crushed single crystals and one from a crushed bulk sample. Individual three-point garnet–hornblende–whole rock ages scatter between 2.603 ± 0.018 Ga and 2.432 ± 0.059 Ga for single garnets. The garnet split from the bulk sample defines an age of 2.463 ± 0.031 Ga, the data point farthest from the regression line for all data points (2.551 ± 0.074 Ga, mean square of weighted deviates = 25). We interpret these data to indicate partial retrogression of a Neoarchean garnet population not significantly older than the oldest obtained three-point age. Well-preserved garnet zoning, regional peak temperatures well below the closing temperature of the Lu-Hf system, and the small scatter of Lu-Hf ages preclude an interpretation of the observed metamorphism and deformation as being Eoarchean in age.

Through almost the entire mantle column, oceanic crust is denser than ambient mantle. In a ca. 100 kilometers thick channel below the lower-upper-mantle boundary (LUMB), however, this relation is reversed. Hence, this channel constitutes a trap for oceanic crust and several recent studies have indeed proposed large ponds of crust at this depth. Accumulation of crust would be expected to be continuous, while sequestration into the lower mantle should be episodic due to the metastable nature of the gravitational trap. Non-steady-state concentration of crust in the channel would be associated with variations in Earths volume in the order of several millions of cubic kilometers. While transfer of crust from the upper mantle into the channel causes volume increase, the collapse of crust into the lower mantle would be associated with net volume decrease. We propose that collapse events could be associated with rising mantle plumes, hence, a net volume decrease of Earth would precede the eruption of large igneous provinces (LIP). A dramatic volume loss in 650 kilometers depth might be able to pull down the surface for a brief time. Such an event might be expressed in an outstanding sea-level-drop before the eruption of LIP. This hypothesis is confirmed by a review of eustatic sea-level changes accompanying late Paleozoic – Cenozoic LIPs activity showing that a majority of LIP emplacement are shortly (< 500 kyr) preceded by an episode of up to 50m (average of 25m) eustatic sea-level fall, with return to pre-perturbation levels at the onset of LIP eruption.

We present the results of reprocessing the reflection-seismic traverse E1, which was acquired as part of the Swiss National Research Program using explosives and Vibroseis trucks as sources. The E1 transect spans from North to South, crossing the allochthonous Helvetic nappe stack, the eastern extensions of the Aar- and Gotthard-massifs, the Northpenninic Bündnerschiefer nappe, and finally the Middlepenninic Suretta-nappe along with the underlying metamorphic Sub-penninic nappes. We applied Kirchhoff prestack depth migration (KPSDM) and interpreted the results with the aid of geological surface data. In addition, we employed another advanced depth migration method, Coherency Migration (CM), for the reprocessing. This migration was conducted in 3D, taking into account the true coordinates of the sources and receivers. Unlike the processing done in the 1980s, we migrated the shot gathers separately and stacked them afterward. The migration results so far reveal a south-dipping Moho on the European side, extending as far south as Swiss coordinate 180, with an up to 5 km thick band of reflectors above the Moho, interpreted as reflective lower crust. A prominent discrete reflector is located at the top of this band. Our initial 3D cube suggests a west-dipping component of the Moho orientation in the northern part of the study area. Additionally, a bright reflector is visible at the Urseren-Garvera zone, which can be traced southward down to a depth of almost 25 kilometers. The next steps include analyzing the Vibroseis data to investigate whether an Adriatic indenter can be identified in the southern section of E1.

Quantifying the topographic evolution of mountain ranges through time is essential for our understanding of geodynamic forces that shape Earth’s surface, orographic and regional climate change, and the distribution of biodiversity.
Altough being one of the most studied mountain ranges worldwide, the surface elevation history of the European Alps is not well constrained. Stable isotope paleoaltimetry relies on the systematic decrease of oxygen (𝛿¹⁸O) and hydrogen (𝛿D) isotopic composition of precipitation with increasing elevation. Contrasting temperature-corrected near-sea level pedogenic carbonate 𝛿¹⁸O values with time-equivalent 𝛿D of K-Ar dated, clay-bearing fault gouges allows for the calculation of the differential elevation between a foreland basin and an orogen’s interior through time. Recent paleoaltimetry research with focus on the Central Alps indicates elevations >4 km during the Mid-Miocene. With a spatio-temporally enhanced coverage of the European Alps, we present estimates of the paleoelevation covering the time interval between ca. 23 and 12 Ma. By integrating our results with paleoclimate simulations across various topographic scenarios, the contribution of local elevation, complex climate change and regional topographic configuration may be isolated. Our estimations indicate peak elevations of >4 km in the Central Alps already during the Early Miocene (ca. 23 Ma). 𝛿D values from fault gouges suggest that the Eastern Alps were significantly lower than the Central Alps between 21 and 16 Ma. Finally, our results highlight the Mont Blanc massif in the Western Alps, did not exceed an average elevation of ca. 1 km until the end of the Miocene.

The Sibela Mountains of Bacan island in eastern Indonesia contain one of the Earth’s youngest metamorphic complexes, now exposed at elevations up to 2000 m. Exhumed basement consists of Permo-Triassic (c. 249-257 Ma) granitoids and metamorphic rocks. Mica ⁴⁰Ar/³⁹Ar and apatite (U-Th-Sm)/He data from these rocks indicate that they were rapidly exhumed in the Pleistocene (c. 0.7 Ma) accompanied by partial melting. The rapid exhumation observed on land was associated with significant subsidence in adjacent basins offshore that reach depths up to 2.4 km. Neogene metamorphic core complexes and other metamorphic complexes are well-known from eastern Indonesia, and they usually record much higher exhumation rates than those reported from older classic metamorphic core complexes found in other parts of the world and require a different formation mechanism. Unlike classic metamorphic core complexes that are characterized by low-angle detachment faults, the Bacan metamorphic rocks were exhumed on steep bounding normal faults forming a rectilinear block pattern. A similar exhumation mechanism can be observed on the island of Sulawesi. We suggest such complexes be termed metamorphic block complexes (MBC). The Bacan MBC is exceptionally young and like the other east Indonesian complexes was rapidly exhumed during subduction rollback.

The coupling of laser ablation systems with inductively coupled plasma-mass spectrometers (LA-ICP-MS) was introduced in the 1980s. Since then, this technique has become indispensable for rapid, in-situ trace element and isotopic analysis of both natural and synthetic solid samples. Its applications extend across various fields, including chemistry, material science, geosciences, as well as biological and environmental analysis, bio-imaging and forensic investigations.

The software G.O.Joe is designed to calculate trace element concentrations in solid samples analyzed by LA-ICP-MS analysis, incorporating several types of optional interference corrections. Written in the Dart programming language using the Flutter framework, G.O.Joe operates online, eliminating the need for installation and allowing access from any location with an internet connection. This facilitates immediate data evaluation and the efficient processing of large datasets.

G.O.Joe features an intuitive user interface that simplifies the data evaluation process. This includes straightforward selections of peak- and background signals, importing instrument settings and reference material compositions to convert the measured raw signals into element concentrations. A major advantage of the software is the implemented correction measures for isobaric interferences and abundance sensitivity. The output, in the form of an Excel (.xlsx) file includes calculated element concentrations, associated statistical parameters, and input data alongside instrument settings to ensure transparent data processing.

Key features of G.O.Joe are demonstrated by processing the mineral chemical analyses of tungstates (e.g., scheelite) and silicates (e.g., garnet), demonstrating that G.O.Joe is a time-efficient, transparent and user-friendly software for LA-ICP-MS trace element analysis.

Analytical methods for inorganic chemistry are found to be differentially effective for specific combinations of target elements, sample matrices and concentration ranges. Consequently, it is a significant challenge to ensure that the results provided in element concentrations are independent of the analytical method employed on the sample matrix. In order to address this issue, reference materials are produced and certified. However, even with the most rigorous production and certification procedures, it remains challenging to accurately determine the "true" concentration values due to the combined effects of measurement protocols and sample matrix. In particular, when dealing with "normal" (non-reference) samples, these effects may introduce a bias into the measurements. When compiling measurements from different analytical approaches and time periods into consistent data sets for further data analysis these method induced biases present a significant challenge. To explore and quantify the extent of methods/matrix-specific offsets between measurement batches, we exploited chemical analysis data from the database for reference materials, GeoReM. The selected data sets from GeoREM of the standards AGV-1&2, BCR-1&2, BHVO-1&2, BIR-1, BRP-1, JA-2, JB-1, OU-6 and W-1&2 initially comprised 83,158 measurements. Following homogenisation and filtering of the samples to ensure robust statistical analysis, 55,413 measurements remained. The statistical analysis (ANOVA) shows that the most frequently occurring offsets between methods are LA-ICP-MS to ICP-MS, followed by XRF to ICP-MS and finally XRF to LA-ICP-MS.

A sample of the leucomonzogranite from the central area of the Meißner Massif (Germany, Saxony), also known as 'Riesensteingranit', was the subject of round 51 of the GeoPT proficiency testing programme that included participation by 112 geoanalytical laboratories from 43 countries.

In the 1960s, the ‘Riesensteingranit’ was previously sampled and certified as the reference material GM by the Zentrales Geologisches Institut Berlin (German Democratic Republic) in the 1960s, in accordance with the Council for Mutual Economic Assistance Standard 2299 (1) .

To enable full certification of materials from the GeoPT proficiency testing programme in accordance with the latest version of ISO Guide 35:2017, a rigorous certification protocol has been developed and published (2).

This protocol has now been applied for the first time in GeoPT Round 51. Certified values for the new certified reference material IAG GMN-1, Meissen granite is certified for nine major elements and thirty-nine trace elements, values of which are reported together with a thorough description of the sample (3). These results are presented and compared with the data from GM.

1 Kaemmel, T., Schrön, W., & Störr, M. (2011) in Zur Geschichte der Geowissenschaften in der DDR - Teil 2, Vol. 18, M. Guntau, W. Pälchen, M. Störr, & O. Hartmann (Eds), Verlag Störr, Ostklüne, pp 167 - 174

2 Potts, P.J., Webb, P.C., & Thompson, M. (2019) Geostandards and Geoanalytical Research 43, 409-418 doi:https://doi.org/10.1111/ggr.12261

3 Potts, P.J., Webb, P.C., Gowing, C.J.B., & Renno, A.D. (2024) Geostandards and Geoanalytical Research, doi:https://doi.org/10.1111/ggr.12553

Handheld and portable X-ray fluorescence (XRF) spectrometers have evolved in recent years from being used primarily as metal sorting tools in scrap yards to becoming instruments of high analytical performance. However, this trend has not been fully embraced by the academic and research community, and there are several reasons for this. In this presentation we will provide a comprehensive description of the capabilities of these instruments, particularly in the context of geoanalysis and archaeometric research. We will cover typical analytical performance indicators, including instrument stability, limits of detection, precision and accuracy, and reproducibility of quantification. The latter is strongly influenced by different types of sample preparation, i.e., pressed pellets, packed powders, or loose powders - considerations that need to be addressed before taking these instruments into the field.

For analysis, we will use a TRACER 5g and different preparations of soils and archaeological ceramics. We will show that the different types of sample preparation lead to different quantifications, and we will evaluate what measures can be taken to avoid such pitfalls. Analysis of soils and ceramics directly in outcrop is a common practice that presents additional complexities for accurate elemental characterization. For this application, we will explore how the combination of sample characteristics, analytical questions, and XRF physics are directly related. The presentation will provide a realistic assessment of the analytical performance of portable XRF instruments by offering a robust analytical evaluation that dispels existing myths surrounding this technique.

The synergy between Geoparks and research facilities provides unique opportunities to promote young researchers and to exchange present state knowledge. In this connection, the Geo-Umweltpark Vogtland and the Faculty of Spatial Information of the University of Applied Science have collaborated on more than 15 projects in recent years.

The research activity includes several areas of geomatics, comprising spatial data analysis, geodata management, adjustment calculations, statistics, and geovisualization. Here, the Geo- Umweltpark Vogtland supports thesis work, seminar papers, and research development projects. Prominent examples are the 3D modeling of the Theuma slate mining, the conception of the geopark trail system, and the cultural heritage visualization of the Falkenstein municipality.

Our example perfectly underscores the fruitful collaboration between science and geoparks. Particularly, the progressive digitalization of geological processes and cultural history, and geological and hydrological mapping are keys to the preservation of our geoheritage.

Geoparks serve as an important link between science and the public. They enhance regional development and sustainable economies while offering fascinating insights into geology and the profound history of our planet. Geoparks provide universal access to the Earth's habitats, fostering a greater respect for nature within society. A special quality seal is the status of "UNESCO Global Geopark," which highlights geoparks on an international level. The preservation of geological heritage is especially significant for this status.

The UNESCO Global Geopark Ries pursues two main strategies to improve geosite protection. Firstly, the designation and expansion of protected areas are crucial. However, the legal protection of geosites poses a challenge for many stakeholders in Germany because there is no explicit protection status for geotopes! Thus, the Geopark Ries collaborates with local nature conservation authorities to protect geotopes by aiming for their designation as natural monuments.

Secondly, geoparks indirectly improve geosite protection by raising public awareness of the region's unique features. In recent years, the Geopark Ries has implemented various projects to better visualize geology. Most of these projects enhance several geological features for visitors with informational offerings. Through active promotion using tours, information boards, and hiking and biking trails, the Geopark Ries conveys geological expertise to the general public. Special programs for schools and families strengthen regional identification from an early age. Moreover, the development of a geotope ensures its ongoing maintenance by partners.

3D prints have proven to be a powerful visualization tool, captivating the interest of the general public and sparking meaningful discussions. However, simply translating digital geological models into 3D files for printing can complicate the process and diminish engagement with the resulting physical prints. Addressing these challenges necessitates optimizing the geological models specifically for 3D printing.

While digital geological 3D models offer flexibility in displaying various geological information, 3D prints are inherently more static. Strategic contextual edits can focus the print on key complexities, guiding viewers towards deeper comprehension. However, caution must be exercised to avoid misinterpretation or confusion through excessive exaggeration or simplification.

The diverse range of printing technologies and materials available requires a thorough understanding of their constraints and limitations, while also claiming the advantages they offer. Models should be tailored for seamless printing on the chosen type of machine, minimizing the need for adjustments or extensive post-processing

Decisions regarding color are crucial in the printing process, as they can significantly influence the effectiveness of the prints based on the context of the models and the target audience.

By meticulously addressing these aspects, 3D prints can serve as compelling introductions to complex digital geological 3D models and the broader topic of geology.

The Federal Company for Radioactive Waste Disposal (Bundesgesellschaft für Endlagerung – BGE) has the task of searching Germany’s subsurface for the best-suited location in terms of safety requirements for a deep geological repository for high-level radioactive waste. In this role and during the current phase of the Site Selection Procedure, BGE is in charge of collecting and interpreting data from existing sources. In this contribution, we focus on the process of collecting, digitalizing, and providing geological data for the evaluation process.

Past data collection efforts have shown that important data frequently only exists on paper and is distributed over various physical locations in the archives of state geological surveys or companies from related industries. Therefore, since 2019, BGE has been scanning and digitalizing significant numbers of data files with support from contractors.

BGE’s own data management team focusses on collecting relevant data, documenting incoming files, and providing homogenized compilations to the site-evaluation teams. The aim is to provide a comprehensive and easy-to-use data basis for the Site Selection Procedure. This final provision step is particularly challenging with regard to the large number of data sources with varying data formats. Current solutions are based around custom in-house software for the identification of well locations, associated documentation, and GIS plugins, e.g., for spatially informed browsing of incoming file metadata. Finally, BGE will present the main decisions towards the identification of siting regions for surface-based exploration in a way that is both understandable and traceable to the public via a web interface.

Regular and irregular hexahedral grids are a common geometric primitive used to represent spatial property distributions. It is often required to calculate closed isosurfaces based on these given spatial properties for visualisation and computation purposes. This talk aims to introduce an efficient method for generating multiple surfaces from a given hexahedral grid. First, it will provide an overview of the structure of different kinds of hexahedral grids, such as regular voxet-based grids and irregular stratigraphic grids. Subsequently, we will present a performant algorithm to generate multiple closed isosurfaces at once for a given hexahedral grid with a specific property and a set of isovalues. Finally we will discuss real-world use-cases and performance numbers.

Die Bibliothek der Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) in Hannover pflegt seit den 1980er-Jahren einen hausinternen Thesaurus, der zur Erschließung der Bibliotheks- und Archivbestände verwendet wird. Anfang der 2000er gab es im Rahmen eines Multithesaurus-Projektes ein Mapping mit dem englischsprachigen GeoRef-Thesaurus und dem französischsprachigen Thesaurus des Geologischen Dienstes von Frankreich. Alle drei Vokabulare haben sich im Laufe der folgenden Jahre auseinanderentwickelt. Der BGR-Thesaurus wurde zuletzt 2018 als Printausgabe veröffentlicht. In einem zurzeit laufenden BGR-internen Projekt werden die Erschließungsarbeit und die hierfür verwendeten Methoden für die Zukunft auf eine zeitgemäße, solide Grundlage gestellt; hierbei spielt Linked Open Data (LOD) eine zentrale Rolle. Um diesem Projekt Vorschub zu leisten, wird der BGR-Thesaurus aktuell in eine LOD-Repräsentation überführt. Im Vordergrund steht neben der Nutzung des Resource Description Framework (RDF), insbesondere der durch das Simple Knowledge Organization System (SKOS) definierten Strukturen, die Anreicherung und Verknüpfung mit sowohl fachspezifischen als auch allgemeinen externen Datenquellen. Ein erster Prototyp für die interne Nutzung in der BGR wurde unter Verwendung der Open-Source-Software Skosmos implementiert. Aktuelle Herausforderungen bestehen in der Datenbereinigung, der Verlinkung zu anderen LOD-Beständen (u. a. GND, Wikidata), der zukünftigen Pflege des Thesaurus und der Aktualisierung des Begriffsvokabulars.

Sachsen ist reich an Bodenschätzen und verfügt über einen einzigartigen geologischen Datenbestand. Einen signifikanten Anteil bilden von der SDAG Wismut erhobene Daten der Buntmetall- und Spaterkundung - finanziert aus dem DDR-Staatshaushalt.

Die Wiedervereinigung Deutschlands 1990 stellte eine Zäsur dar: Der einstige staatliche Auftraggeber verschwand; gleichzeitig wurde die SDAG Wismut in das Sanierungsunternehmen Wismut GmbH umgewandelt, dessen Aufgabe in der Sanierung der Hinterlassenschaften des ostdeutschen Uranbergbaus bestand. Vorhandene geologische Daten aus 45 Jahren Erkundungstätigkeit wurden im Geologischen Archiv zusammengeführt. Ein Mandat, den umfangreichen Datenbestand proaktiv öffentlich verfügbar zu machen, bestand hingegen nicht. Die Nutzung der überwiegend analogen Daten war beschwerlich – auch wegen der Wismut-spezifischen Dokumentenstrukturen und der einstigen Geheimhaltungspraktiken.

Im Zuge des Projektes ROHSA 3 (Rohstoffdaten Sachsen) erfolgte unter Federführung des Sächsischen Landesamtes für Umwelt, Landwirtschaft und Geologie die Recherche, Sicherung und Neubewertung geowissenschaftlicher bzw. rohstoffbezogener Daten. Die geologischen Informationen der Wismut GmbH wurden im Auftrag des LfULG erschlossen, datenbankgerecht aufgearbeitet und in Wert gesetzt. Sie können nun gezielt über die Rohstoffdatenbank (https://www.rohstoffdaten.sachsen.de/suche) recherchiert und online genutzt werden. Durch die digitale Erschließung von Archivdaten konnten bislang unbekannte geologische Informationen öffentlich bereitgestellt werden. Sie flossen bereits in neue 3D-Untergrundmodelle sowie die Vorbereitung neuer Infrastrukturprojekte ein. Ihre digitale Verfügbarkeit eröffnet die Möglichkeit, durch den Einsatz künstlicher Intelligenz neue Erkenntnisse zu gewinnen, um so den Wirtschafts- und Wissenschaftsstandort Sachsen zu stärken.

In Fortsetzung der Kooperation von Freistaat Sachsen und Wismut GmbH soll mit Unterstützung der Bundesregierung die Aufarbeitung der verbliebenen rohstoffrelevanten Wismut-Bestände forciert und somit ein substanzieller Beitrag zur nationalen Rohstoffstrategie geleistet werden.

The GOAL network consists of more than 100 geoscientists from 15 countries (Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, Germany, Mexico, Nicaragua, Paraguay, Peru, Uruguay and Venezuela). Members’ expertise covers geology, volcanology, paleontology, mining, environment, georisk management and climatology. The network, exists since 2002 under the auspices of the German Academic Exchange Service (DAAD) to join Latin American Earth Scientists who carried out their studies in Germany. The network stimulates professional cooperation between the Latin American and German geoscientific communities. GOAL helps to promote exchange, disseminate knowledge of research results and new applied technologies, and initiate joint research opportunities.
Today's dynamic world requires almost constant adaptation. Against the background of growing geo-environmental concerns, geoscientific knowledge dissemination becomes a challenge. This is where GOAL plays an important role, e.g., with the upcoming workshops on ''Geoscience Communication''. Our goal is clearer and more effective communication within geoscience research centers, companies and educational institutions. Advantages of the network are: Joint meetings, fundedfinancially supported by the DAAD;, Aaccess to a powerful international network;, eases Facilitating joint projects between Germany and LatinamericanLatin-American countries. We cordially invite young geoscientists with affinities to Latin America to join the GOAL network!

In abandoned mines in the Harz Mountains, peculiar corrosion phenomena can be observed on steel structures (pipes, steel struts, rails) whose cm-sized structures are reminiscent of closed clam shells. They have an internal cavity filled with an aqueous solution and do not contain any macroscopic organisms. The only known scientific description of these ferruginous shelled structures (FSS) comes from a lead-zinc mine in the Pyrenees (Fernández-Remolar et al., 2015).

The samples were investigated by electron microprobe and Raman spectroscopy. The shells can be subdivided into three layers, an inner layer of spherical crystallised goethite, a central layer of laminated magnetite followed by a layer of goethite and lepidochrochite. The outer two layers (approximately 1 mm thick) are composed of numerous lamellar of approximately 5-10 µm thickness. The spherical crystallisations of the inner layer grow into the aqueous filling. Areas containing magnetite correlate with decreased organic carbon. The highest organic carbon and sulphur in the innermost layer, indicate microbial activity such as a sulphur metabolism.

Microbial formation of the FSS, as described in the literature, could explain the preferred direction of growth direction of the crystallisations and the zoning. The organisms could derive energy from iron oxidation, leading to biomineralisation. The presence of magnetite can be attributed to the biological reduction of iron(III) oxides, as it occurs only in the central layer, where it is isolated from atmospheric oxygen and the aqueous filling.

Fernández-Remolar DC et al. 2015, Formation of iron-rich shelled structures by microbial communities. J Geophy Res, Biogeosci., 10.1002/2014JG002745.

While the sedimentological development of the Quaternary in the northern Upper Rhine Graben is well researched, there is a lack of in-depth investigations for the underlying Iffezheim Formation. To close this gap, detailed sedimentological and sequence stratigraphic investigations were carried out on an approximately 220 m long Pliocene core section of the Riedstadt-Erfelden research borehole drilled in 2020 and 2021, which is also the northernmost borehole of its kind in the Upper Rhine Graben to date. This work presents insights into sedimentary facies of the Upper Pliocene Iffezheim Formation and investigates the cyclicity in sedimentation dynamics based on facies analysis including petrophysical measurements (total gamma ray logging, spectral gamma ray logging and magnetic susceptibility measurements). Relatively thick successions of channel sediments and pedogenetically influenced floodplain deposits accompanied by abundant crevasse splays indicate an anastomosing fluvial style for the river Rhine system during the Upper Pliocene. By analyzing the cyclicity, three orders of magnitude of cycles could be identified, each consisting of predominantly stacking patterns of base-level-rise half-cycles with some intermediate base-level-fall half-cycles. In addition to a detailed facies model of the Rhine system in the Upper Pliocene of the central, northern Upper Rhine Graben, this work thus also offers an approach to correlate further sections of the Iffezheim Formation basin-wide. Based on this, the knowledge gained can be used stratigraphically in a wider region and context.

The Monte Viso Ophiolite complex, situated in the penninic of the Italian Alps, is one of the well studied examples of a subducted oceanic core complex. The serpentinized peridotites comprises enclaves of a wide variety of low temperature, high pressure rocks including eclogites and exceptional rok types such as omphacitite and jadeitites. The occurrence of the jadeitite is particularly intriguing, because the Monte Viso jadeites is one of the only two known examples classified as r-type jadeitites, i.e., formed by metamorphism of a fluid altered protolith.This is a contrast to the jadeitites from China and Myanmar, which formed directly by precipitation from a fluid. This work investigates the formation of these r-type jadeites. Our samples show evidence for the presence of jadeitites in new geological subunit, with significantly different textures. A detailed investigation of the textures and pyroxene composition suggests that original jadeite rich pyroxene can be distinguished from the fluid derived diopside rich crystals. Additionally, a study of the zircons in the jadeitties gives insight into the magmatic protolith, and the degree of fluid alteration in the jadeitites.

Situated in the northeastern part of the Saghro massif within the Eastern Anti-Atlas region of Morocco, the Igudrane/Imiter mine area has undergone significant rifting processes attributed to the formation of the Pan-African belt. These processes, spanning from the Precambrian to the Phanerozoic, have led to the development of intricate deformation structures and distinctive mineralization zones within the mine, making it a compelling subject for further geological studies. Extensive rock sampling conducted in the Igudrane mining area, complemented by detailed field notes, aimed to produce updated maps and deepen the knowledge of the area.

Subsequent studies utilizing optical microscopy revealed the presence of at least two distinct magmatic/plutonic rocks with granitoid composition, alongside metamorphic rocks, all intersected by several andesitic and rhyolitic dyke systems. Despite variations, the majority of the samples share common main minerals such as quartz (Qz), plagioclase (Pl), K-feldspar (Kfs), biotite (Bt) and amphibole (Amp) with apatite (Ap) and zircon (Zr) identified as the principal accessory mineral phases.

Furthermore, scanning electron microscopy (SEM) has been employed to provide further insights into the chemical composition of the minerals under study, enabling detailed analysis of both internal and external textures that reveal significant differences in zonation patterns.

The wide range of chemical and isotopic signatures preserved in minerals of the apatite supergroup makes them truly useful across a broad spectrum of scientific applications, helping geoscientists to understand magmatic, metamorphic, paleoenvironmental, and (paleo)ecological processes. Ongoing progress in method developments has made secondary ion mass spectrometry (SIMS) one of the primary techniques for micro-scale apatite investigations. The ability to sample in situ picogram masses with SIMS allows for isotope studies of both rare and heterogenous samples. However, the availability and quality of reference materials (RMs) necessary for quantitative measurements has hobbled key applications.

Improvements of apatite isotope analysis method have been a major focus of our nearly decade-long initiative [1,2]. We are continuing our efforts to characterize RMs and advance SIMS measurement methodologies for sulfur, boron, oxygen, and U-Pb isotopes in apatite and related materials. By making use of existing mineral collections, we have been investigating the chemistry-dependent behavior of different samples under primary ion beams, along with the surface properties of polished mounts and calibration strategies. Such improvements in our fundamental understanding of these analyses will be crucial for future apatite research initiatives. Characterization studies devoted to the coming generation of apatite RMs have documented the challenges faced even by more traditional analytical techniques operating at much larger sampling scales.

References:

[1] Wudarska et al. (2021), Geostand Geoanal Res. doi:10.1111/ggr.12366.
[2] Wudarska et al. (2022), Geostand Geoanal Res. doi:10.1111/ggr.12416.

Acknowledgements: This research has been supported by the International Association of Geoanalysts (Geoanalytical Research and Networking Grants).

The fast and accurate on-site analysis of brines and ore leaching solutions is still a challenge. Conventionally used laboratory methods such as ICP-OES or ICP-MS are not suitable for on-site applications due to high plasma gas flow rates and power consumption. On the other hand, portable X-ray spectrometers are not able to analyse light elements such as Li, Na or K with adequate accuracy. Therefore, a fast and precise method combining on-site suitability and quantification of light elements would be preferable.

Here we investigated the potential of the Micro-Discharge Optical Emission Spectroscopy (µDOES) for the on-site and on-line analysis of lithium ore leaching solutions, whose industrial end product is an essential precursor for the battery industry. The technology is based on a micro-plasma, which is directly created inside the liquid sample without any carrier gas by applying high voltage pulses to electrodes enabling optical emission spectroscopy on-site^[1].

After parameter optimisation (conductivity, wavelength selection, discharge energy), on-line measurements of different process steps at a lithium hydroxide pilot plant were carried out. In addition to Li, other elements like Na, K, Ca, Mg or Rb were quantified. The technique demonstrated its capability for the fast and precise on-site analysis of major components and trace elements in saline solutions. Results showed good agreement with established laboratory methods, such as ICP-OES and ion chromatography.

[1] B. Wiggershaus, M. Jeskanen, A. Roos, C. Vogt and T. Laurila, Trace element analysis

in lithium matrices using Micro-Discharge Optical Emission Spectroscopy, J. Anal. At.
Spectrom., 2024. DOI:10.1039/D4JA00044G.

The purpose of this study was to investigate the chemical composition of red iron pigments based on waste iron sulfate. As a model waste, waste iron(II) sulfate from Grupa Azoty Zakłady Chemiczne POLICE S.A is used. Obtained pigments were also compared to commercially available materials from various manufacturers like BASF (Germany), Percheza (Czech Republic), Boruta-Zachem (Poland) or Edan (Poland).

Pigments were analyzed with several analytical methods like: X-Ray Diffraction, Dynamic Light Scattering, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, Helium Ion Microscopy and Scanning Electron Microscopy.

In determining the phase and chemical composition, we encounter some limitations of the methods. For example, during XRD analysis using Cu-Kα source, quartz-derived phases were visible in some commercial pigments. Comparing these results with FTIR analysis, the presence of quartz was confirmed, but in addition, vibrations from CaCO₃ were seen, which was not visible in XRD. Only by changing the radiation source in XRD to Co-Kα was it possible to detect phases originating from CaCO₃.

Precise knowledge of the contents of samples is frequently lacking prior to analysis. This is particularly true for external samples, which are frequently examined without prior information. Consequently, it is crucial to combine various analyses to obtain the most accurate results.

The Mesoarchaean West Rand Group displays a layer-cake stratigraphy with lithostratigraphic units correlatable on a basin-wide scale. The ~5 km thick succession consists of fluvial braidplain and shelf deposits, which range from shallow inner shelf marine orthoquartzites, outer shelf argillites to starved shelf iron-formations. Three major sequences are present: Sequence I (Hospital Hill Subgroup), Sequence II (Government Subgroup) and Sequence III (Jeppestown Subgroup).

Sequence I was deposited during a period of highstand of sea-level, sequence II during a period of relative lowstand, and sequence III during a period of relative highstand coupled with high rates of sediment supply. Isopach, depofacies and palaeocurrent analyses indicate that strata in the western to northwestern parts of the basin were deposited under more proximal sedimentary conditions compared to those in the central or southeastern parts. Little relationship between the present outline of the basin and the distribution of depofacies suggests that the original sedimentary basin was significantly larger in areal extent.

Depofacies and thickness distribution, as well as synsedimentary deformation of strata, indicate that the basin was most probably of flexural tectonic origin. These findings support deposition in a wide, shallow, and rather stationary foreland basin, with an axial zone towards the west/northwest and low amplitude peripheral bulge to the east/southeast. Such shallow foreland basins, with abundant sediment bypassing, are thought to be associated with windward-facing orogenic fronts. High rates of erosion along such fold-thrust belts lead to ineffective loading and advancement of the orogenic front, as well as an oversupply of sediment.

The Bromacker Project (https://bromacker.de/) investigates the “Ursaurier” vertebrate Lagerstätte of the same name in Early Permian redbeds of the Tambach Formation. Its geologic-paleontologic subproject contributes key parameters such as paleoecology, paleoclimate, paleogeography, and depositional environments to the reconstruction of the Tambach Basin.

Two research boreholes were drilled in 2022 and 2023 to complement information from outcrops and several legacy boreholes near the Bromacker site. Forschungsbohrung (Fb) Altenbergen 01/2022, located in the northwest of the basin, cored 250 m of the Tambach Formation and terminated in the basal Bielstein Conglomerate Member. Fb Tambach-Dietharz 01/2023 in the southeast of the basin terminated at 199 m depth in the pre-Tambach Rotterode Fm. The Bielstein Conglomerate Member is correlated between both boreholes; it consists of well-rounded volcanic clasts of a braided river setting. In the Altenbergen borehole, fluvial deposits of the Tambach Sandstone Member consist of massive mudstones interbedded with laminated shale in fluvial floodplain settings interspersed with temporary ponds and paleosols; whereas this member is present as gravelly fluvial-channel sandstone facies in the Tambach-Dietharz borehole. Fluvial channel deposition is terminated by prograding alluvial fan sedimentation represented by the Finsterbergen Conglomerate Member present in both cores. The influx of fluvial sandstones bearing plutonic and metamorphic clasts, observed in both boreholes, marks the exposure of the Ruhla Crystalline Complex to the west.

Especially the Tambach Sandstone Member shows different sedimentary facies throughout the core on a distance within the basin of around 4 km, showing also a clear distinction between habitats within the Tambach Basin.

A common tool in provenance studies of clastic sedimentary rocks is the geochemical composition for identification and differentiation of potential catchment areas. However, not only source rock lithologies but also for instance sorting, alteration, leaching or new mineral formation influenced by the climate during erosion, transport and deposition or by diagenesis during burial influence the geochemical provenance signal (Augustsson et al., 2023). Therefore, the consideration of the genetic and diagenetic changes of the deposits, i.e. their development over time, plays an important role for a meaningful interpretation of geochemical data for provenance studies.

To test this, we investigate Permo-Carboniferous terrestrial sandstone and conglomerate. The units represent changing palaeogeographic and climatic conditions. In addition, the deposits underwent diagenetic changes during deep burial and partial uplift to present-day borehole depths of 1500-2500 m. We use polarization, cathodoluminescence, and scanning electron microscopy, microprobe analyses, XRD, XRF, and ICP analyzes. Initial results indicate correlations of the Chemical Index of Alteration and K₂O/Na₂O with the preservation state of detrital feldspar and the diagenetic clay minerals kaolinite and illite. Th/Sc and Y/Zr correlate with lithoclast composition (felsic versus mafic igneous and metamorphic) and the intergranular components (matrix versus cement). This allows the separation of Carboniferous and Permian samples. It is a result of changing climatic and diagenetic conditions.

Reference: Augustsson, C., Aehnelt, M., Olivarius, M., Voigt, T., Gaupp, R., & Hilse, U. (2023). Provenance from the geochemical composition of terrestrial clastic deposits-a review with case study from the intracontinental Permo-Triassic of European Pangea. Sedimentary Geology, 106496.

The Triassic Skagerrak Formation in the Central Graben of the North Sea is a fluvial-lacustrine succession that is historically difficult to subdivide in the subsurface into lithostratigraphic units, and to correlate between different wells and licence blocks. The formation consists of various sandstone members interspersed by mudstone members with relatively poor age constraints. Raman spectroscopy of heavy minerals in combination with chemostratigraphy is an effective tool to identify lithological differences and to reconstruct provenance of the individual members. The lower parts of the Skagerrak Formation (Judy Sandstone Member) are generally characterised by ultra-stable heavy mineral assemblages, indicating multi-recycling of nearby Palaeozoic cover units, while the directly underlying Bunter Sandstone additionally has several unstable mafic heavy mineral species, probably derived from local basement highs (e.g., Forties Montrose High). Up-section within the lower parts of the Joanne Sandstone Member there is a switch to more immature apatite-rich heavy mineral assemblages, likely related to a source change to Fennoscandian basement at the Norwegian margin. A mafic marker horizon within the upper Joanne Sandstone indicates input from contemporaneous volcanism at the Carnian-Norian boundary, and may represent a significant basin-wide unconformity.

The present-day hyperarid Sahara is the largest hot desert in the world, but its development in deep time is largely unknown. The inception of persistent Northern African aridification has been variously linked to the onset of Northern Hemisphere glaciation at the beginning of the Pleistocene. However, eolian bedforms and dust records, reinforced by modelling studies, indicate transient periods of aridity have started North Africa already in the latest Miocene during times of Northern Hemisphere cooling. For the globally warm Pliocene epoch intermittent aridity is suggested for the western Sahara by dust records from the Canary Islands. In contrast, onshore evidence of contemporary North African climate is missing, because of the lack of well-dated Neogene sections in the Sahara.

Here we present a thoroughly sedimentological, paleoenvironmental and geochronological investigation of the Neogene continental Wadi El Natrun Formation in the northern fringe of eastern Sahara (Wadi El Natrun, northern Egypt). We differentiate seven sedimentological facies types, each distinguished by characteristic palaeobiota. These are in an ascending order: braided river and overbank facies, which contain abundant fluvial and riparian vertebrates; a lacustrine black shale facies rich in phytoclasts; a lacustrine limestone facies with characean algae; a marine limestone facies with planktonic foraminifera and marine molluscs; a playa lake facies with a thalassosaline ostracod and gastropod fauna; an ephemeral stream facies with Skolithos and Ophiomorpha ichnofabrics; and finally an eolian dune facies with polydomic ichnofabrics.

These changes in sedimentological facies indicate the long-term temporal progression of desertification in Northern Africa well before the Quaternary.

Deep-time reconstruction of palaeoenvironments is of great importance for many geoscientific and life science disciplines. Various geoarchives provide information on ancient dust fluxes that affect climate and biodiversity and which also hold clues to palaeogeography. Furthermore, "rates" are integral to almost all related research questions, requiring the use of state-of-the-art dating techniques on various materials that act as dust traps.

Intercontinental dust fluxes, such as those from the African deserts to South America cause large-scale geo-bio interactions. Such wind-blown particles fertilise the vibrant ecosystems of the Amazon rainforrest, where the dust is rapidly metabolised or bioturbated by countless organisms. Saharan dust transported to Europe is also difficult to trace back through time, as single events rarely result in detectable deposits. This calls for alternatives to conventional drilling or outcrop studies. Datable dust archives containing detrital heavy minerals provide snapshots of dust transport in a high spatio-temporal resolution. Therefore, analyses like LA-ICP-MS U-Pb age determination on detrital zircon or SEM-EDX chemical characterisation on large numbers of individual terrestrial dust particles are applied.

However, even the most advanced techniques for exploiting new geoarchives are of limited benefit without information on the original dust sources and their availability over time. For this reason, the evolution of drainage systems through time is studied in particular, as rivers are often the primary source of desert sediments. This whole approach involves compilation and processing of large datasets, e.g. a circum-Atlantic zircon age database (N>5000, n>275000). Initial results are very encouraging and go beyond the proof-of-concept stage.

Clay-rich formations are internationally considered as ideal seals for underground disposal of radioactive waste [1, 2]. In the context of site exploration programs transport characteristics must - among other information – be locally quantified [3].

Here we present noble gas profiles from Hondingen, southern Germany [4], an area already disqualified as a siting region due to the shallow depth of the Opalinus Clay formation and an active fault zone. The sampling procedure generally followed guidelines for drill core sampling of the recent Nagra drilling campaign [5], refining procedures originally developed elsewhere [6 - 10].

We compare our data with analytical solutions [11] and numerical simulation results [12]. The ⁴He concentration profile has reached steady state. Within the clay barrier, the transport is diffusion dominated with the minimum porewater residence time calculating to some million years.

[1] M. J. Hendry et al. (2015) Geofluids 15(3) [2] Clay Club Catalogue (2022) NEA, OECD [3] A. Bath, et al. (2023) Appl. Geochem. 159 [4] K. Leu et al. (2023) J. Appl. Region. Geol. [5] D. Rufer and M. Stockhecke (2021) NAB 19-13(1) NAGRA [6] J. Lippmann et al., (1997) IAEA-SM-349/36; [7] K. Osenbrueck, et al. (1998) GCA 62(18) [8] A. P. Ruebel et al. (2002) GCA 66(8) [9] M. Mazurek et al. (2011) Appl. Geochem. 26(7) [10] D. Rufer, et al. (2017) Proc. Earth Planet. Sci., 17, [11] J. N. Andrews (1985) Chem. Geol., 49 [12] D. L. Parkhurst and C. A. J. Appelo (2013) Techniques and Methods, 6(A43), USGS, USA

The Opalinuston-Formation in Southern Germany comprises a thick (>100 m) sequence of Middle Jurassic claystones. In parts of Bavaria and Baden-Württemberg, the formation has been designated as a sub-area by the Federal company for radioactive waste disposal (BGE), indicating that favorable geological conditions for the final disposal of high-level radioactive waste can be expected there. However, coherent geological data for the complete formation is often lacking. Here we present new data on the geological variability of the Opalinuston-Formation based on four drill cores, each of which penetrated through the entire formation, and parts of the over- and underlying rock strata outside the sub-area. After completion of the drilling work, the cores were examined in high resolution for their petrophysical properties and element distribution using non-destructive analytical tools such as XRF core scanner and multi-sensor core logger. Furthermore, one sample per core meter was taken for a precise stratigraphic classification of the rocks and a geochemical-mineralogical and sedimentological characterization. Results exhibit notable geological variability at the investigated localities, particularly with respect to the Si/Al ratio. This is interpreted as changes in grain size due to relative sea-level fluctuations during deposition, and is thus useful to reconstruct stacking patterns of parasequences. In summary, this contribution highlights the geological variability of the Opalinuston-Formation in Southern Germany and discusses the possibilities of a sequence stratigraphic approach to identify the most suitable parts of sub-areas in claystone formations for the final disposal of high-level radioactive waste.

Ensuring the long-term safety of underground repositories for high-level radioactive waste requires a comprehensive understanding of overburden stability. In this BGE-funded project, we investigate past landscape evolution and erosion dynamics in the South German Scarplands utilizing a multidisciplinary approach. Through geomorphic analysis, stratigraphic reconstruction, thermochronology, cosmogenic nuclides, and landscape evolution modelling, we aim to quantify the intricate interplay of geological processes shaping overburden topography over a million to a thousand year timescales.

Our findings reveal that long-wavelength uplift pulses and graben formation control long-term erosion within the region. Notably, the latest post-15 Ma uplift pulse has led to a southeastward shift of the drainage divide between the Main/Neckar and the Danube rivers, accompanied by substantial river captures and localized pulses of erosion. Associated peak erosion rates can be up to several tens of meters per thousand years and create a cascading effect of erosion away from the original capture sites along the antecedent river valleys. The magnitude of these events is constrained by the accumulated differential uplift between the base-level of the Rhine to the west and the uplifted area to the east (i.e., the Swabian Alb).

Furthermore, we highlight the profound influence of the exposure of 'weak' rocks and associated drainage system reorganization on both the past and future evolution of the South German Scarplands. Our comprehensive quantitative analysis contributes valuable insights into the complex interplay of geological processes governing landscape evolution and surface erosion, which are crucial for assessing the long-term safety of underground repositories for radioactive waste.

To assess the present and future conditions of potential deep geological repository sites, understanding their evolution in the past is mandatory. Here, glaciation cycles strongly affected the long-term thermo-hydro-mechanical (THM) evolution of the geosystem.

The AREHS project studies the effects of time-dependent boundary conditions (BCs) on the long-term evolution of large-scale hydrogeological systems. The focus is on numerical modeling using the open-source multi-field finite element code OpenGeoSys with THM couplings. The impact of the glacial THM loading is taken into account using complex time-dependent THM BCs. A generic geological model for a clay host rock formation including predominantly sedimentary rock layers is applied. Assuming the plastic flow behavior of the sedimentary rocks to share qualitative features, the same generic material model is used for all layers: The elasto-plastic modified Cam clay model can describe qualitatively a range of relevant effects (dilatancy, contractancy, consolidation etc.) with few material parameters. Special emphasis is put on the specification of a suitable initial state: To this end, an initial simulation is carried out, where a reasonable plastic pre-consolidation is adjusted. Then, the thermodynamic state is transferred in full to the subsequent simulation of two glacial cycles. As a main result, the glacial cycles lead to persistent deviations in the subsurface, e. g. long-term pressure anomalies due to THM coupling. However, under the chosen assumptions, only the first glacial cycle leads to pronounced (contractant) plastic flow whereas the second cycle merely shows elastic rock behavior.

Funding: BASE Grant No. 4719F10402 (AREHS project)

The lowlands of northern Germany and neighbouring countries have been subject to glaciation several times in the pleistocene. These glacial periods have left behind several erosional features, of which tunnel valleys are the deepest and most remarkable. The current consensus of the respective field of science is that those valleys are formed by the flow of melt water below the melting glacier.

Within the site selection procedure in Germany for a high-level nuclear waste (HLW) repository, a safety assessment for 1 million years has to be conducted. During this time span repeated glaciations are likely to occur in northern Europe, and therefore repeated glacial erosion is to be expected.

However, beyond the safe inclusion in the selected host rock of a HLW repository, a sufficient stability of the overlaying overburden horizons must be ensured.

To address the numerous uncertainties regarding the glacier melting process and the conditions of the sedimentary layers eroded by melt water transport, we have developed a combined modelling approach. This method comprises a three-dimensional deterministic numerical modelling of the tunnel valley genesis with FLAC3D and a multivariate probabilistic modelling with GoldSim to account for the remarkable uncertainties over 1 Ma. The approach allows to evaluate the resistance of different overburden stratigraphies against deep glacial erosion processes and therefore can be a valuable contribution to the site selection process.

The research project presented here is funded by BASE under the grant number FKZ 4721F10401.

Hydrothermal activity is common at active volcanoes. Volcanic gasses rise and form strong acids that lead to fluid-rock interactions affecting a rock’s mineral assemblage by dissolution and remineralization, eventually influencing essential rock parameters like strength and permeability. Despite the far-reaching consequences for the stability of a volcanic edifice, our understanding of extent and variability of hydrothermal alteration is often limited. Within Multi-Marex we aim to better understand the causes and effects of hydrothermal alteration and volcano stability on land and underwater. By close-range remote sensing, we analyze hydrothermal alteration, aiming to describe the morphology (shapes) and optical appearance of hydrothermally active sites over scales and to reveal the general pattern of alteration and its regional variability. We give an overview of optical methods for tracing hydrothermal alteration, compare patterns observed at different systems, and expand our view to the submarine regime. In particular, we compare the alteration pattern at Nisyros, a hydrothermally active volcano in the Aegean Arc with hydrothermal-dominated or magmatic-hydrothermal systems at locations elsewhere. The approaches and the pattern of hydrothermal alterations observed vary, but all systems have in common that there are patterns that can be detected and that indicate variability of gas flux and alteration and therefore zones of contrast considering materials, permeabilities, strength, or other physicochemical properties. Revealing these patterns is beneficial for detailed and focused further investigations and may be particularly useful for monitoring and future risk assessment studies.

The Delitzsch carbonatite complex, located 25 km NW of Leipzig, constitutes a late Cretaceous ultramafic lamprophyre (UML)-carbonatite occurrence covered by Cenozoic sediments [1,2]. We have analysed UML samples from drillcores for their mineral chemistries by electron-probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to better understand their mantle source and magmatic history.

Based on their mineralogy, the rocks can be classified as alnöite, olivine-alnöite, phlogopite-olivine alnöite, and damtjernite [3]. Compositionally, the rocks lie between UMLs and kimberlites with Mg# [= Mg/(Mg+Fe)] ranging from 0.72 to 0.79, and are likely derived from partial melting of carbonated peridotite at pressures of around 5 GPa [4]. Their deep origin is further corroborated by a garnet-peridotite mantle xenolith which equilibrated at 1350 °C and 5.8 GPa.

Olivine is the most common mineral in the studied rocks and exhibits complex zonation. The core compositions show different groups that we attribute to i) mantle xenocrysts (high Mg# and NiO), ii) antecrysts which have crystallized at different levels in the lithosphere (variable Mg# and NiO), and iii) carbonatitic olivines (extremely low NiO). The rims show distinct differentiation trends converging to Mg# of about 0.87 with decreasing NiO contents.

Our results demonstrate the complex magmatic history of the Delitzsch UMLs and provide evidence for a formerly thick lithospheric mantle beneath Central Europe.

[1] Seifert et al. (2000) Lithos 53: 81-100
[2] Krüger et al. (2013) Chem Geol 353: 140-150
[3] Tappe et al. (2005) JPet 46: 1893-1900
[4] Gudfinnsson & Presnall (2005) JPet 8: 1645-1659

Research on hydrothermal alteration investigates the impacts of hot, corrosive fluids circulating within a volcano, which are crucial for comprehending volcanic risks, slope instability, and steam-driven eruptions. Observable phenomena like fumaroles and mineral deposits at the surface offer direct evidence of subterranean hydrothermal systems or volcanic unrest, detectable through remote sensing techniques. In this study, we introduce a novel Hydrothermal Alteration Index (HAI) derived from Ultra Blue, Red, SWIR 1, and SWIR 2 bands of multispectral satellite imagery, facilitated by Google Earth Engine (GEE), to monitor hydrothermal changes. Identifying three primary alteration zones covering a total area of 600,000 m² at Lastarria Volcano, our findings are corroborated by field surveys, affirming the utility of HAI. Through temporal analysis, we pinpoint three distinct events indicating expansion, contraction of alteration zones, and the emergence of new sulfur flows. By aligning spatiotemporal patterns detected by HAI with independent monitoring data, we infer heightened hydrothermal activity. Lastly, we offer fresh insights into the progression of surface hydrothermal phenomena, starting from the summit crater and extending towards the flank region.

North Atlantic rifting during the Palaeocene-Eocene was accompanied by explosive volcanic eruptions. These led to distribution of about 200 ash layers of mainly basaltic composition covering wide areas of NW and Central Europe, also reaching the Tethys realm (Obst et al. 2015).

The ash layers, which are often interbedded in clayish successions, are known from offshore and onshore drillings but also from surface exposures, e.g., cliff sections or clay pits. In part, the pyroclastic material is well preserved in eogenetically carbonate cemented concretions, which occur in northern Germany and Denmark in glacially dislocated rafts of Eocene sediments or as isolated glacial erratic boulders named cement stones (“Zementsteine”).

Petrographic and sedimentological investigations of numerous cemented ashes from several locations in northern Germany (Fehmarn, Klütz Höved, Groß Roge, Grimmen, Wobbanz/Rügen and Greifswalder Oie) allow to distinguish different types of preservation. Single and rarely double ash layers up to 15 cm in thickness may either be preserved undisturbed, intensively bioturbated or reworked. Especially in shallow marine environments, the ashes can partly be eroded by currents or waves, and the basaltic glass particles may be redistributed.

In detail, variations in thickness and grain size as well as varying glass composition and alteration can be used to characterize distinct layers and will help to correlate ashes of the same volcanic event between different occurrences. Furthermore, changes of the sedimentation environment are documented in a NW–SE transect reflecting still water conditions in the central part of the North Sea Basin and near-shore environments at the eastern basin margins.

Volcanic flank instability poses a significant multi-hazard risk, encompassing caldera collapses, landslides, rock avalanches, and potential tsunami generation in active and dormant volcanoes. The mechanical strength and regions of hydrothermal alteration may play a fundamental role in locating and scaling volcano instability. Therefore, investigating hydrothermal alteration, which consequently alters the physicochemical properties of volcanic rocks, is crucial to better understanding the processes that lead to volcanic flank instability and collapse.

Here, we use the southernmost exposure of the Aeolian volcanic archipelago, La Fossa of Vulcano Island (Italy), as our focus site. La Fossa's history of mass wasting, regions of hydrothermal alteration, and episodic fumarole activity make it an ideal natural laboratory for our investigation. Here, we used high-resolution drone remote sensing techniques coupled with in-situ uni-axial compressive strength measurements to identify regions of hydrothermal alteration and assess their associated compressive strength properties. In summary, our results show (1) a heterogeneous distribution of alteration types and intensities, (2) a relationship between increasing alteration intensity and decreasing rock strength, (3) a correlation between regions with the weakest rock strength and the most intensely altered areas, and finally (4) a spatial association of alteration and deep scars resulting from erosion and landslides. Our combined approach allows us to explore the association between rock strength and hydrothermal alteration, enabling us to understand volcanic flank instability better and help us improve future hazard assessment.

Although micro-XRF as an analytical technique was developed over 20 years ago, it is with the continuous advancement of computing and hardware technology that it has become more powerful than ever and a routine part of many geoscience characterization workflows. A principal reason for this is the systems capability to analyse large samples at micrometer scales with very minimal sample preparation. This flexibility makes the micro-XRF system ideal for analysing field samples (e.g., hand specimens, drill cores) in the laboratory, and thus easily and timeously enabling relevant decisions to be made about up- or down-scaling information or additional sample analysis in any given workflow. In addition, micro-XRF can analyse a range of sample sizes, from large specimens (over 10´s of centimeters) to those prepared as the commonly used polished thin sections or epoxy briquettes. Furthermore, results of micro-XRF analysis range from major, minor and trace elemental chemistry in semi- and fully-quantified form, to derived mineralogy, thus yielding data-rich information across a range of geoscience fields such as petrology, sedimentology, geochemistry, paleontology, economic geology, amongst others. The visualization of the elemental chemistry and mineralogy on such a large scale is extremely intuitive and relevant in geosciences, as it enables the user to directly link the sample’s visual structure to its chemistry. This presentation will review these capabilities in the world of geoscience and discuss the possibilities for the future.

µXRF is a versatile technique that has been used in various geoscientific fields, particularly for the mapping of larger hand specimen or drill cores. It is easy to use, non-destructive and requires only little sample preparation, enabling the acquisition of 2D element distribution and mineral identification via EDX spectra. However, a limitation is the diffraction of the X-ray beam by the crystal lattice, which can produce peaks that overlap with actual element peaks, thereby affecting chemical quantification and mineral identification. Previous research, such as Nikonow et al. (2016), has demonstrated methods to eliminate these diffraction peaks from µXRF spectra. Additionally, diffraction can be used to identify individual grains within a mono-mineralic domain, such as quartz, without the need for thin section preparation. Since diffraction depends on the angle between the crystal lattice and the X-ray beam, differently oriented grains will produce diffraction peaks at different energies in the spectrum and can be distinguished from each other in the energy-dispersive µXRF spectrum. This technique enables not only the identification of optically similar minerals in the drill core (e.g. magnetite and ilmenite), but also the extraction of grain shapes and measurement of their 2D size, area, and orientation in the cutting plane and allows for quantitative textural analysis, helping to understand e.g. igneous processes (Higgins 1998). The application of this method is demonstrated on drill core sections from magnetitite layers of the Upper Zone of the Bushveld Igneous Complex, South Africa.

Micro X-ray Fluorescence (MXRF) spectrometers enable non-destructive and elemental analysis of a wide variety of solid samples with a lateral resolution of a few tens of micrometers using focusing optics. Confocal MXRF (CMXRF) offers additional depth-dependent measure­ment capabilities, based on a three-dimensional probing volume created by the confocal ar­rangement of a focusing lens in the excitation and detection channel. Therefore, CMXRF pro­vides micro-scalic resolved measurements of complete sample volumes by depth profiles (1D), cross section mappings (2D) and stacked element distribution images (3D). The strengths, challenges and potential of a modified (confocal) MXRF tabletop spectrometer for non-destruc­tive and depth-sensitive element analysis will be illustrated by geoanalytical and geo-related appli­cations:

The first application is the three-dimensional analysis of mineral inclusions. The sophisticated compositional studies and identification of mineral phases by CMXRF provides micro-scalic resolutions with certain limitations due to X-ray absorption, but also preserves the integrity of isolated inclusions for further analysis.

Another example is the study of biomineralization products, due to the biomimetic behavior of deep-sea sponges under extreme conditions resulting in the formation of novel three-dimen­sional composites. Several mineralization products such as atacamite, goethite and lepido­crocite have been studied by three-dimensional reconstruction of the elemental distribution of the formed composites.

The third application is the depth-sensitive analysis of the elemental composition of ce­ment stone corrosion zones simulating the acidic chemical attack on concrete samples. The interest in describing those corrosion processes is motivated by defining the occurring kinetics and deriving information about the persistence, strength and durability of concrete.

Micro-X-ray fluorescence spectroscopy (XRF) represents a well-established and complementary analytical technique to electron beam energy dispersive spectroscopy (EDS) for the detailed characterization of elemental composition in samples. The integration of the X-ray source (namely XTrace) facilitates the application of XRF technology within a scanning electron microscope (SEM). Micro-XRF excitation analysis is a specialized small-area/volume technique, particularly suitable for beam-sensitive samples due to the absence of charging effects. The technique offers significant advantages, including enhanced sensitivity for trace element detection, the capability to excite higher energy X-ray lines (spanning a full spectral range to 40 keV), and the acquisition of information from greater sample depths even in centimeter level.

The deployment of advanced X-ray polycapillary optics enables the focal spot size of the X-rays to be reduced to 10 microns, all within an X-ray source compatible with SEM ports. X-ray energy detection is performed using the existing EDS detector integrated into the SEM system. Consequently, the SEM system attains dual-source capability, encompassing both electron and X-ray sources (as illustrated in Fig. 1), thereby expanding the possibilities for material characterization. This dual-source capability is termed "Full Range EDS," leveraging the novel analytical potential arising from the combined dual excitation of micro-XRF and electron beam sources alongside an EDS detector. This dual-beam system, allowing samples to interact with either the SEM's electron beam, the XTrace’s X-ray photons, or both simultaneously. Full Range EDS confers numerous advantages over traditional EDS, providing researchers with deeper insights into the elemental and compositional intricacies of their samples.

Brandenburg’s surface geology predominantly consists of Quaternary sediments, with sequences averaging 50 to 80 meters (locally up to 500 meters) in thickness. Research up to 2008 on heavy mineral composition facilitated the lithostratigraphic classification of fluvial deposits, revealing frequency and compositional variations. Stratigraphic classification in Brandenburg relies primarily on pollen analysis of interglacial, predominantly limnic deposits, and small-scale gravel counts of (glacio-)fluvial and till sediments, leaving sandy components unrepresented methodologically.

To establish a comprehensive provenance analysis, the method development presented here includes both the heavy and light mineral fractions. The geochemical composition of the samples is determined semi-quantitatively using spectral analysis. In this project, 24 sand samples from the drill core Kb Borgisdorf 1/06 were examined to reconstruct the distribution patterns of Saale Late Glacial to Weichsel Early Glacial sediments in Brandenburg. The focus of method development is on sand deposits that cannot be classified by pollen and clast analysis. All samples were prepared for both polarization microscopy and Mineral Liberation Analysis (MLA), maintaining a grain size range of <200 μm. This saves time and provides a comprehensive dataset that is better comparable with conventional analyses. The data produced by the MLA are compiled into large databases and statistically analyzed, utilizing mineralogy and grain parameters such as size, length, width, and roundness. By comparing with comprehensive geochemical and mineralogical data, the method was validated. Initial results show that additional preparation yields comparable results and that samples without density separation are statistically reliable for heavy mineral analysis.

Elemental overview of a thin section (2.5 x 2 cm) typically requires large-area mapping over numerous fields, which can take several hours with conventional approaches. To shorten the measurement time without compromising data quality, we utilize the annular EDS FlatQUAD detector, capable of collecting up to 2.4 million counts per second. This speed reduces the required time-per-pixel, dwell time per frame, and overall measurement time, enabling the mapping of major elemental distributions across an entire thin section in under a minute.

In this example of a garnet-spinel peridotite from South Africa, we compare measurements of the entire thin section which took several hours to cover the 8 x 14 fields, resulting in high statistical accuracy compared with ultra-high-speed mappings revealing elemental distribution in less than one minute measurement time for the entire thin section. This example showcases the efficiency and capability of advanced EDS technology in geological studies. Extending the measurement time will result in much better statistics, and the software can detect mineral phases automatically; however, the major elements distribution is clearly visible in a short analytical run time for the entire thin section, including offline extraction of spectra from each pixel in the map for further quantification.

Astronomical insolation forcing is well established as the underlying metronome of Quaternary ice ages and Cenozoic climate changes. However, its effects on earlier eras (Mesozoic, Paleozoic, and pre-Cambrian) are less understood. In the first part of this presentation, I will argue that formally defining 405,000-year eccentricity cycles as chronostratigraphic units (astrochronozones) throughout the Phanerozoic eon is a crucial research goal for the next decade. Establishing a common cyclostratigraphic framework to harmonize cyclostratigraphies between key sections in Europe and North America (in particular for the Devonian) is of primary importance. The goal of defining Phanerozoic astrochronozones would enhance our understanding of how astronomical forcing has shaped Earth's climate over geologic time.

Subsequently, I will discuss several lines of evidence suggesting that Devonian oxygen deficiency was sensitive to rhythmic astronomical forcing. Nonetheless, the question of why some anoxic events were more severe than others remains unresolved. Therefore, it is increasingly important to employ cyclostratigraphy to distinguish between different climate modes of the Devonian and to improve our understanding of the role of astronomical forcing in Devonian ocean anoxic events.

Rhenish Massif and Ardennes are the type regions of the classic Gedinnian, Siegenian, and Emsian stages (and subunits) of the Lower Devonian, which are mainly defined by brachiopods. In the course of the ongoing taxonomic revision of the Rhenish Lower Devonian representatives of the phylum, numerous new biostratigraphic data have been obtained. The revised biostratigraphy includes 25 taxon range and 20 assemblage zones from the Pridoli to the Eifelian, which can be further subdivided into subzones. Although Lochkovian, Pragian, and Emsian GSSPs have long been defined elsewhere on the basis of pelagic guide fossils, the classic Ardenno-Rhenish stratigraphy is still an important reference in the Lower Devonian, e.g., for the envisaged redefinition of the basal Emsian GSSP.

The biostratigraphic utility of brachiopods is restricted both by their limited palaeogeographic distribution and their dependence on the facies. In the case of the Rhenish Lower Devonian, specific subtypes of the rhenotypic facies have to be considered (e.g., eurhenotypic, allorhenotypic and pararhenotypic facies). Nevertheless, the Rhenish brachiopods are excellent guide fossils, and thanks to close palaeobiogeographic relationships the revised biostratigraphy can be used with reservations in Western Europe and North Africa, i.e., within the boundaries of a ‘Maghrebo-European’ palaeobiogeographic unit. Here, correlations of regional brachiopod and global pelagic biostratigraphies are possible. To conclude, it can be said that the revised Lower Devonian brachiopod stratigraphy has the potential of providing a fine-scaled biochronological framework for future stratigraphic, palaeoecological, and palaeobiogeographic studies.

The super-continent Pangea was characterised by strong continentality because of climatic change from an icehouse earth during late Pennsylvanian and early Permian via an increasingly warm earth during middle–late Permian into the early Triassic super-hot house. Consequently, marine incursions, caused by the glacial cycles (cyclothems), decreased during the early Permian. Because of increasingly absent marine deposits in the Permian, the correlation of the continental deposits with marine zone-fossils (ammonoids, conodonts, fusulinids) becomes complicated. Very helpful for the correlation would be radioisotopic ages from intercalated volcanites. Unfortunately, during late early Permian, volcanism decreased in the continental Euramerica. In the middle and late Permian, no radioisotopic ages exist so far for Euramerica. Newest Late Pennsylvanian and earliest Permian radioisotopic ages based on the U-Pb CA-ID-TIMS (chemical abrasion-isotope dilution-thermal ionisation mass spectrometry) method fit well with continental and marine biostratigraphic correlations. However, some new high-precision U-Pb CA-ID-TIMS ages, especially from the Thuringian Forest Basin, conflict with the biostratigraphy and other radioisotopic ages in European basins. They are even in contrast to the climate-stratigraphy in Euramerica, particularly to the outspread of wet and, later, dry reds beds, which, of course, only provide rough interregional time markers. The question arises, what do these highly precise radioisotopic ages tell us? Are they really the decisive eruption ages or do they represent (far) older crystallisation processes in the magma chamber? In any case, we should only trust ages (and even biostratigraphic data) that are supported by cross-correlations with data from different independent stratigraphic methods.

The world’s largest ammonite, Parapuzosia (P.) seppenradensis (Landois, 1895), has fascinated the world since the discovery in 1895 of a specimen measuring 1.74 metres (m) in diameter near Seppenrade in Westfalia, Germany. Subsequent findings of this taxon have been rare. For this study (Ifrim et al., 2021), the historical specimens have been revised, and abudant material from England and Mexico was documented. It comprises 154 specimens of large (< 1 m diameter) to giant (> 1m diameter) Parapuzosia from the Santonian and lower Campanian, mostly with stratigraphical information. High-resolution integrated stratigraphy allows for precise trans-Atlantic correlation of these occurrences. The Tepeyac section in northeastern Mexico, where 66 specimens of diameters from 10 to 150 cm were found in their original layer was documented with integrated stratigraphy. With 330 ammonoids and >100 inoceramids, among other fossils, it is the section with the richest fossil record in that interval. It has become Associated Stratotype Section and Point for the base of the Campanian (Gale et al. 2023). The high- resolution correlation allows for further insight into the palaeobiology, evolution and dispersal of worlds largest ammonite

References
Gale, A., et al. 2023. The Global Boundary Stratotype Section and Point (GSSP) of the Campanian Stage at Bottaccione (Gubbio, Italy) and its Auxiliary Sections: Seaford Head (UK), Bocieniec (Poland), Postalm (Austria), Smoky Hill, Kansas (U.S.A), Tepayac (Mexico). Episodes. doi: 10.18814/epiiugs/2022/022048.
Ifrim, C. et al. 2021. Ontogeny, Evolution and palaeobiogeographic distribution of Parapuzosia (P.) seppenradensis, the world's largest ammonite. PLoS ONE 16, e0258510. doi: 10.1371/journal.pone.0258510.

After the peak warmth’s of mid-Cretaceous times, progressive climate cooling occurred during the late Cretaceous, with a global temperature decline in the order of Cenozoic cooling without signs of major and persistent glaciation. Thereby, the Maastrichtian marks a cool greenhouse period with different non-analog boundary conditions in comparison to today. Global mean temperatures, polar ice extents, regions of deep-water formation, types of vegetation, as well as patterns and variability of precipitation and evaporation were all different. Repeated multi-million-year long periods of climate cooling and warming occurred during the cool Maastrichtian greenhouse. Particularly, the latest Campanian–early Maastrichtian witnessed substantial deep-water cooling as well as a carbon cycle perturbation expressed by a long-lasting negative carbon isotope excursion. Our understanding of climate and carbon cycle dynamics is still limited for times prior 66 million years, particularly for the Campanian–Maastrichtian transition. The lack of highly resolved stratigraphy introduces severe uncertainties in the quality and interpretation of global correlation. Here we present the present state in the development of an astrochronology for the Maastrichtian stage that integrates sedimentary cyclicity, carbon isotope and magnetostratigraphy in combination with biostratigraphic events from the successions of Zumaia, Sopela, Bidart and the GSSP locality Tercis-les-Bains belonging to the Basque-Cantabrian and Aquitain basins in Spain and France. The development of a Bay of Biscay Maastrichtian record will provide new insights about the phase relation between orbital forcing and carbon cycle response, as well as temporal relations to changes in ocean chemistry, circulation and sea level, and the ecosystem response.

Aim of the project is the collection of data sets of solid material and groundwater physical and chemical properties for suitable host rocks such as claystone and various crystalline rocks. The data sets are stored in a database that compiles measured and already established and technically substantiated reference values from different data sources (databases, scientific publications) worldwide. Statistical variance, localisation and assignment to a certain geological unit are included. However, the main focus is on host rocks that have been investigated in Germany and surrounding countries like Belgium, Switzerland and the Scandinavian Countries.

The derived reference data sets will be used in Step 2, Phase I of the site selection procedure due to legislation of the StandAG to evaluate the geological units of an area of interest. A lack of measurement data is to be expected for many of the areas to be assessed by the BGE, so that the reference data sets are of great relevance for the representative preliminary safety investigations (rvSU). In the case that for an area-specific evaluation no or too few specific measured values are available parameter models have to be developed in order to approximate the site-specific properties. The aim of the rvSU is to be able to differentiate between subunits within a host rock type and within an investigation area. Thus, it should not only be possible to derive generalised reference data sets for the host rock type but also to provide differentiated value ranges based on the geological context.

The combination of TEM, based on focused ion beam (FIB) sample preparation, and high-resolution SEM allows the investigation of grain and phase boundary networks from nanometer to centimeter scale, i.e., over about 8 orders of magnitude. Recent studies show that the boundaries of various minerals in different metamorphic and magmatic rocks are lastingly open on the nanometer scale, due to the elastic response of crystals to temperature and pressure decrease during exhumation of rocks, and can be partly to totally filled with secondary minerals.

SEM measurements on square centimeter large areas in granite indicate that the boundaries between feldspars, quartz and biotite are nearly continuously and up to several hundred nanometer open and partly filled with secondary minerals. It is most likely that the boundaries form networks in even larger parts of the granite, which allow fluid flow. The occurrence of newly grown biotite indicates that open grain and phase boundaries are not just a phenomenon in rocks at uppermost crustal levels but can occur at depths of at least 10-15 km. Open and partly filled boundaries do not only control various physical properties of crystalline material and govern its behavior during different natural and technical conditions as well as in experiment. Such boundaries potentially affect the migration of materials even over larger distances in rocks, for example of radionuclides released from nuclear waste in deep geological repositories. Alternatively, fillings of boundaries by secondary minerals increase the absorptive capacity and, consequently, the bedrock's retention capability of fluid-carried materials.

Ensuring the safety for deep geological repositories for nuclear waste in crystlline host rock necessitates a comprehensive understanding of the far field and it's potential for radionuclide retention. In case of a repository leakage, radionuclides may get mobile and migrate through pathways in rock and aquifers. To asses the uncertainties in forcasting the migration of radionuclides it is essential to incorporate naturally occurring heterogeneities in rock composition and geological structures into the models, e.g. heterogeneities occurring near intrusion margins, tectonically influenced granitic bodies, or metamorphic formations like gneisses. This complexity significantly impacts the modeled radionuclide retention potential compared to simplistic isotropic granite models.
The SANGUR project (Systematic Sensitivity Analysis for Mechanistic Geochemical Models using Field Data from Crystalline Rock) aims to identify crucial parameters and their uncertainties essential for modeling radionuclide retention in crystalline rock. Our study presents a comprehensive workflow modeling how petrological variations in both granitic and metamorphic crystalline host rocks influence radionuclide retention. Utilizing Multinary Random Fields geostatistics, we simulate crystalline rocks based on analyzed spatial rock data to quantify uncertaintiesand to determine the appropriate model scale. The petrological variance is then considered for the chemical modeling through software such as PHREEQC or Geochemist's Workbench©: Surface Complexation Models (SCM) in chemical modeling software calculate partition coefficients (Kd values) for radionuclides, such as uranium, in diverse mineral environments in combination with varying aqueous phases. To enhance and simplify models, global sensitivity anlsysis is applied to determine critical features for radionuclide retention.

A robust prediction of the recent crustal stress field has a crucial role for forecasting the short- and long-term safety of a high-level radioactive waste repository. However, no reliable and comprehensive prediction of the complete stress tensor for Germany is possible with the amount of stress data records available. The only comprehensive data set is the World Stress Map, which, however, only provides the orientation of the maximum horizontal stress. Stress magnitude data records of sufficiently reliable quality are only available from a few boreholes. However, 3D geomechanical-numerical models, which represent the geometry of the subsurface and its mechanical properties and are calibrated with stress magnitudes, allow a continuum-mechanics based prediction of the complete stress tensor and its lateral and vertical variability.

A new geomechanical-numerical model – developed within the SpannEnD 2.0 (Spannungsmodell Endlagerung Deutschland) project - provides new insights into the recent crustal stress field of Germany. A new model, by combining ~25 existing 3D geological models and a five time higher vertical resolution of ~45 m allow a better mechanical representation of individual units and mechanical inhomogeneities. In addition new stress magnitude data records are compiled and used for calibration.

The results provide a comprehensive prediction of the complete stress tensor for Germany and can be used for a wide range of scientific questions and applications. Examples are the prediction of the fracture potential, the slip tendency of faults or as boundary conditions for small-scale models.

The Site Selection Act (StandAG) for Germany´s nuclear waste repository states that the presence of post-Eocene (< 34 Ma old) faults is an exclusion criterion that makes any potential site unsuitable. Identifying such faults is problematic in the German uplands (Mittelgebirge), where large areas have no Cenozoic deposits and exposure quality is generally low. Radiometric age dates of faults are still very sparse and unlikely to become widely available in the near future. We have used different methods to identify potential post-Eocene faults. These include GIS-based analysis of the spatial relationships of faults with post-Eocene units on existing maps as well as automated lineament extraction and visual interpretation of possibly fault-related topographic features from high-resolution DEMs. Fault and lineament density maps were created. All results based on geological maps are affected by their uneven quality and inconsistency. Much of the variation is caused by different mapping concepts, particularly for the 1:25.000 sheets. The fault networks have been analyzed for fault length distribution and topology to identify interpretation problems. Fault lengths and connectivity are underestimated. A Python code has been developed to automatically extract stratigraphic throws of faults from digital geological maps with an aim being to make better predictions about fault trace lengths. A concept for safety distances around faults has been developed that considers not only wall damage along faults, but also damage at fault tips, bends, steps and interaction zones. Proof of post-Eocene faulting will require additional analyses for each suspected case.

Magma contains information on its source and on the processes the magma experienced en route to the surface. This information is, however, locked in the chemical and isotopic composition of minerals and groundmass. Petrologists can help understand volcanic phenomena and geochemical processes. The recent basaltic eruptions on Iceland and in the Canary Islands have now given us the opportunity to study the evolution of individual rift eruptions in extreme detail. Time-resolved sampling of erupted products allows detection of mineralogical and chemical changes on a daily to weekly timescale and gives us the opportunity to correlate this information with seismic data and changes in eruptive style. This allows us to identify rapid changes in magma composition and interpret these changes in respect to magma sources, magma storage, and magma transport.

The recent eruptions at Fagradalsfjall have shown rapid compositional changes in major and trace elements during the eruption, which has been interpreted as reflecting different mantle components that are sampled during a single eruption. Stable isotopes such as oxygen remain virtually unchanged, however, through the 2021 to 2022 events. The 2021 Tajogaite eruption on La Palma also showed rapid changes in lava composition during the first weeks of the eruption. This together with the seismic record indicates that the eruption was initially fed from a crustal reservoir, but later from a deeper upper mantle reservoir. In contrast to Fagradalsfjall, initial magmas show variable oxygen isotope compositions. The implication of these commonalities and differences are discussed in full in this presentation.

The Ohře/Eger Graben (OEG) marks one of the important spots of the Mesozoic to Cenozoic rift-related volcanic activity in central Europe, and extends over a length of more than 250 km. Here, the volcanic edifices comprise monogenetic maar-diatremes, scoria cones, and lava domes as well as large polygenetic stratovolcanoes. Their composition ranges between melilitite, nephelinite, basanite, and phonolite. It is precisely the northern flank of the OEG, where the timing of eruption has been sporadically dated with outdated methods.

Recent 40Ar/39Ar age analysis has provided new insights, revealing a chronological sequence spanning from 77 to 10 Ma and reshaping our understanding of eruption dynamics in the northern OEG rift structure. The oldest volcanics are melilite-bearing rocks with ages of around 77 to 65 Ma. With eruption ages at 10 Ma, the nephelinitic Landsberg and Buchhübel, as well as the basanitic Ascherhübel of the western Elbe Zone are the youngest volcanoes from the northern rift flank. Volcanoes of the Erzgebirge and Lusatia erupted between 37 and 29 Ma and 35 to 26 Ma, respectively. The age determination of the Vogtland yields younger ages at 30 to 23 Ma.

Melilite-bearing igneous rocks are known to be derived from the partial melting of dolomitic garnet-bearing lherzolite under CO₂-rich conditions at pressures between 27 and 40 kbar. However, there are still unresolved questions regarding their magma evolution. The Vogtland volcanic field is part of the Central European Cenozoic Igneous Province and hosts various olivine melilitite and melilite-bearing olivine-nephelinite diatremes, such as those at Bösenbrunn and Burkhardtsgrün.

The olivine melilitite and melilite-bearing rocks of these two locations are characterized by variable olivine content, often with skeletal or "hopper" morphology. They also contain clinopyroxene, melilite with a typical "pag" structure, magnetite, Cr-spinel, rare nepheline, apatite, zircon, and perovskite. Within some melilitites, the presence of reversely zoned melilite in clinopyroxene-bearing melilitites is probably the consequence of the co-precipitation of melilite with clinopyroxene. As clinopyroxene crystallization initiates, the Al/Mg ratio of the residual melt rises, causing a gradual depletion of åkermanite content from core to rim within the crystallizing melilites. Variations in major and trace elements, along with zoning patterns in coexisting minerals, may be influenced by their affiliation with either Ca-rich or -poor magma series. Trace-element fractionation during differentiation of these parental magmas suggests the existence of two mantle-derived magmas: (i) a melilite-bearing series formed at higher pressures (ca. 35 kbar), which was originally enriched in CO₂, Sr, Nb, and REE (La, Ce, etc) and differentiated at shallower depths, while (ii) a Ca-poor magma began fractionating only at around 17 kbar during magma ascent.

Magneto-mineralogical properties of volcanic rocks can be used to study their emplacement conditions and thus the eruptive behaviour of volcanoes. Two ICDP cores were drilled into the effusive and explosive units of the Bažina Maar, located in the Czech Republic. The drilled volcanic units are up to 160 m thick in total, and consist of lapilli tuff and effusive (sub-)volcanic rocks which are overlain by unconsolidated, highly weathered lapilli and scoria deposits. The units are locally overprinted by apatite-bearing sequences, possibly of hydrothermal origin. We used a KLY-5A Kappabridge to measure the out-of-phase (op) in addition to the traditionally measured in-phase (ip) temperature-dependent magnetic susceptibility and determined Curie-Temperatures (T_c), field depend magnetic susceptibility as well as the anisotropy of magnetic susceptibility (AMS). The most common sources for an op component in igneous rocks are vicous relaxation of superparamagnetic/single domain (titano-)magnetite grains and weak field hysteresis of ferrimagnetic phases like titanomagnetite and pyrrhotite. Ip and op T_cs between 170 – 300°C suggest a Ti-rich titanomagnetite as the main ferrimagnetic phase. Higher T_cs within the explosive products between 450 – 580°C suggest maghemitisation of the juvenile titanomagnetite. The ip AMS component for the effusive volcanic rocks reveals a moderate to steeply inclined magnetic foliation, suggesting an upwards flow as emplacement mechanism. For the lapilli units, the op AMS response is oblique to the ip AMS signal, revealing a magnetic subfabric. Our study demonstrates that the systematic study of ip and op susceptibility can add key information to unravel complex volcanological processes.

The Haukadalur thermal area in southwestern Iceland comprises numerous individual thermal springs, geysers, and hot pots arranged roughly in a north-south orientation. Situated on the eastern slope of a hill, this field is delimited by fissures associated with the Western Volcanic Zone. This study is based on high-resolution unmanned aerial vehicle (UAV) equipped with optical and radiometric infrared cameras to identify over 350 distinct thermal spots across various zones, and puts these in a larger context from geophysical experiments undertaken in the region. Close examination revealed that geysers and hot areas are clusters, but are generally aligning with the presumed tectonic trend in the region. Repeat thermal surveys realized in the past 10 years show systematic and chaotic changes in activity of the geysers. This presentation delves into the structural correlation between the deeper and shallower segments of these geysers, influence of the external effects and water table, and is shedding light on the mechanisms underlying geyser and hot pot activity, with broader implications applicable to thermal fields worldwide.

Geosciences represent one of the most diverse fields of research and therefore provide a superb opportunity to study the complex Earth System, offering manifold perspectives and links to connect with other disciplines. Are we fully exploiting this potential, especially seen the role of geosciences for society, interdisciplinary research and international collaboration?

In my talk, I would like to emphasize on the relevance of geoscience for society by (1) informing the future about, for example, the bandwidth of prospective future changes in key parameters of the Earth System such as, for example, temperature and sea level rise, (2) highlight the potential of Geoscience for collaboration within the Earth-Environment-Human System by providing examples from current and ongoing research, combining, for example, approaches from natural and social science, as well as between scientific and local knowledge, and (3) discuss how we can better support innovative research and cooperation.

The Late Cretaceous collision of the Adriatic microplate with Eurasia led to a predominantly southwest-vergent and in-sequence structural architecture in the Dinarides. During the Paleogene, the deformation front migrated from the Internal to the External Dinarides, resulting in about 130 km of crustal shortening. Fault kinematic data and balanced cross-sections across the External Dinarides reveal contrasting deformation styles along the orogen, separated by a roughly 250 km-long dextral transpressive fault. This fault marks the changes from the southern, southwest-vergent nappe stack segment to the northern, northeast-vergent backthrust-dominated Velebit segment. These backthrusts originated at lateral facies boundaries associated with extensional Mesozoic half grabens.

The contemporaneous deformation of these two domains, indicated by the distribution of flexural foreland basin sediments, marked the end of the Paleogene Dinaric orogeny. Within these Eocene to early Oligocene syntectonic and older Mesozoic carbonate platform rocks, horizontal marine terraces are preserved at elevations of up to 600 meters. Using digital elevation models (DEMs), we extracted terrace surfaces along the Adriatic coast, ranging from Istria in the north to Montenegro in the south. All these flat surfaces are degradational, unrelated to bedding or faults, and located between the present-day Adriatic shoreline and the drainage divide. The area of the extracted marine terraces corelates with a reported positive P-wave tomography anomaly. Based on the reported thinned Adriatic lithosphere beneath the internal part of the orogen, our findings suggest that the Dinarides underwent widespread surface uplift in the Miocene due to mantle delamination with limited Neogene crustal shortening.

The Fichtelgebirge is located between the western edge of the NE-SW striking Eger Rift Zone and the Franconian Lineament. The basement mainly consists of late Variscan granitoids, Paleozoic meta-sedimentary rocks and meta-magmatites. Tertiary sediments are limited to isolated occurrences and basaltic rocks occur mainly along isolated outcrops that are located roughly in NE-direction. However, our current knowledge of the structural inventory of the rocks is limited and the interrelations of fault activity, reactivation potential, volcanism and uplift are not yet fully understood.

In order to improve the understanding of the structural history of the Fichtelgebirge, the orientations and kinematics of 193 fault planes were measured. The results show that most faults strike NNW-SSE, while only a minor number strikes in conjugated directions. Based on the field studies, a detailed paleo-stress analysis of the faults has been carried out and four different stress regimes could be identified: (i) Permo-Carboniferous NNW-SSE compression, (ii) a Late Cretaceous NE-SW compression and (iii) a presumably Neogene NW-SE compression with (iv) a contemporaneous or subsequent NE-SW extension. The first regime created pathways for the ascent of differentiated melts during the Late Carboniferous and Early Permian. The other stress regimes are interpreted to have played a significant role in the Cenozoic uplift of the Steinwald and other mountain ranges in the region by reactivating pre-existing fault systems. It is assumed that faults in the Fichtelgebirge, such as the nearby active Mariánské Lázne fault, carry a significant reactivation potential in the currently NW-SE orientated prevailing compressional regime.

The Pamir-Tian Shan-Hindu Kush orogenic segment at the western edge of the India-Asia collision stands high, reaches deep, transitions from flat to rugged, deforms truly 3D, and stretches wide beyond the direct continental collision zone. Based on data from a cornucopia of geoscience disciplines, we show that mantle driving forces and distinct geometrical and rheological boundary conditions govern the tectonic evolution, i.e., the mantle-crust-surface and hinterland-foreland interactions. We will take the subduction of marginal Indian lithosphere underneath the Hindu Kush and the indentation of the Indian cratonic mantle lithosphere into Asian (Tajik-Tarim) lithosphere since 10-13 Ma as an example for processes in the mantle. We show what effects they have on the deep Pamir crust, the Afghan-Tajik foreland basin, and the Tian Shan; those effects are lithospheric foundering below the Pamir, gravitational spreading of the Pamir-plateau lithosphere, Afghan-Tajik foreland-basin inversion, rise of the modern Tian Shan, and Fergana and Tarim block rotation. Our dataset integrates observations from seismology, petrology, petrochronology, thermochronology, and structural geology.

A structural description of the intra-montane basins establishes the deformation field of the southwestern Tian Shan that faces the Pamir and the Afghan-Tajik Basin and thus the Indian mantle indenter beneath the Pamir and the deformation it imposes—northward indentation and westward crustal collapse. Six major Cenozoic faults traceable over >100 km separate rigid basement blocks; tight synclines occupy their footwalls. These ~E-striking faults reactivate Paleozoic ones, indicate ~N-S shortening with a dextral strike-slip component, connect with ~WNW-striking ones with a strong dextral component, and ~ENE-striking ones confined to the western southwestern Tian Shan. The deformation field resembles that in the Afghan-Tajik Basin fold-thrust belt, and mimics in shape the geometry of the intermediate-depth earthquake zone beneath the Pamir. We infer that the southwestern Tian Shan is involved in the northward motion and westward collapse. The basement-rooted Cenozoic faults require a detachment underlying the southwestern Tian Shan, which should root in the delamination zone beneath the Pamir; a depth of the detachment at the brittle-ductile transition is consistent with the regular spacing of the intra-montane basins. A crustal-scale cross section connects the southwestern Tian Shan, the Afghan-Tajik Basin fold-thrust belt, and the delamination zone, and highlights the evaporite-detachment below the Afghan-Tajik Basin, the mid-crustal detachment below the southwestern Tian Shan, and the rooting of faults of the Afghan-Tajik Basin fold-thrust in the deeper detachment; this may run along the Moho.

The transition from subduction to collision marks a pivotal geological transformation as tectonic plates cease their subduction, giving rise to intense collisions that reshape landscapes and foster the creation of mountain ranges. We use thermo-mechanical numerical modeling to address the dynamics of continental margin subduction and the subsequent transition to collision.

Several collision orogens like the Alps document a typical series of events that are not fully understood:

1. Continental high-pressure (HP) units are formed from upper crust and only during early continental subduction. In a mature collision orogen continental upper crust is detached from lower crust at shallow levels, while lower crust might continue to subduct.

2. These units are rapidly exhumed along the subduction boundary and their final position in the orogen is “in-sequence” on top of the continental nappes and below the oceanic suture. Continental HP-units are sandwiched between units that experienced considerably lower peak pressures.

3. Rapid exhumation of HP units is followed by:

3.1 apparently extensional deformation, of which at least the final stage affects the entire nappe pile;

3.2 a phase of magmatic activity, i.e. the formation of granodioritic and tonalitic intrusions that cut the established nappe pile;

3.2 rapid rise of topography in the orogen.

In order to investigate this sequence of events and recognize factors controlling their timings and necessary conditions we reconstruct transition from subduction to collision with forward modeling. Here, we employ visco-elasto-plastic thermomechanical modeling approach to model subduction process followed by collision.

In recent decades, mining-related activities in the Lusatian lignite mining area have led to an extensive pyrite weathering, contributing thereby to the elevation of sulfate and iron concentrations in the groundwater and surface water.

Due to the complicated pathways of pyrite oxidation and the complex spatial distribution of the pyrite-bearing layers, it is difficult to develop a comprehensive restoration plan. Therefore, developing a quick and non-intrusive geophysical measuring technique for estimating pyrite oxidation in various depths and areas is highly desirable. Previous laboratory studies have shown the effect of iron bearing minerals on the nuclear magnetic resonance (NMR) response signal. However, further research is required to link these findings to the subsurface pyrite oxidation state or the accompanied sulfate concentrations in the groundwater.

To this end, column experiments containing different pyrite mass-percentages are performed under various redox conditions. The pyrite oxidation in the columns is measured via the mass balance between the inlet, the initial content, and the outlet. In addition, laboratory NMR is used to constantly monitor the column for the entire experiment duration. For modeling purposes, we developed a PHREEQC-based reactive transport model to simulate pyrite oxidation inside the columns. A comparison between the model results, laboratory NMR data, and the experimental measurements provides a basis for the future surface-based NMR applications in the field.

The outcome ultimately enables us to estimate the groundwater contamination due to pyrite oxidation with a NMR-based technique that is less time-consuming, more reliable, and less labor-intensive.