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.

In Germany, all nuclear power plants have been shut down and some are already in various stages of decommissioning. All waste volumes that are not deposited in a repository must pass through officially approved clearance procedures, which are regulated in the German Radiation Protection Ordinance (StrlSchV 2021). After clearance, the materials can be fed into further material cycles or disposed of in accordance with the type of release. The release values of the Radiation Protection Ordinance are based on the 10 µSv criterion. This criterion is intended to ensure the protection of the population from ionizing radiation.

Numerical groundwater models can be used to simulate the distribution of radionuclides and provide information on concentrations in space and time, which can be used as input parameters for calculating possible ingestion doses for different exposure paths.

The basic transport processes of advection, diffusion, dispersion, and sorption are implemented in the simulation codes "Simulation of Processes in Groundwater (SPRING)" (König et al. 2023), “DuMux – Dune for Multiphase flow and transport” (Koch et al. 2021) and "distributed density-driven flow (d3f++)" (Fein & Schneider 1999, Fein 2004). Decay chains can also be modeled in the codes.

The model area represents a simple 2D model and a generic landfill body with its various layer compartments and an associated aquifer. In a further model, the infiltration of precipitation water into contaminated soil with mass transport into the saturated zone is considered. This work presents the first results of the generic numerical groundwater models.

The main objectives of this research are to access ground water,a primary source of drinking water in the urban areas of Hawler Erbil and Bnaslawa in northern Iraq, and the non -carcinogenic human health risks of nitrate contamination associated with drinking water quality. For this purpose, twenty seven ground water samples were collected from wells to asses the hydrogeochemical characteristics and ground water quality for both natural and anthropogenic purposes during the wet (May 2020) and dry (September 2020) seasons.During the wet and dry seasons, NO3 in ground water ranged from 14to 61 mg/L and 12 to 60 mg/L with an average value of 35.7 and 29 mg /L, respectively. Approximately 25.92% of the samples exceeded the permissible limit of the WHO (2011) drinking water standard.the ratio of NO3 /Na vs.Cl/Na and SO4/Na vs. NO3 /Na indicate the effect of agricultural activities and waste water leakage from cesspools or septic tanks on the quality of ground water during the wet and dry seasons. The entropy weighted water quality index method ranked 62.5% and 75% of the urban ground water as not recommended for drinking, the remaing samples are moderately suitable in both wet and dry seasons.Due to high nitrate in drinking water, non-carcinogenic human health risk levels vary as infants >child> adults.The main findings obtained from this study can assist policymakers in better understanding the hydrogeochemical properties of ground water in terms of drinking water safety, thereby facilitating the management of water resources to take the necessary measures.

Understanding the biogeochemical processes that lead to the enrichment of dissolved phosphorus in groundwater is crucial, especially as concentrations exceeding 1 mg L^-1 occur in many floodplain and delta aquifers. These elevated concentrations of primarily inorganic orthophosphate can cause eutrophication in surface waters and mobilize toxic elements like arsenic.

Here, we provide a comprehensive overview of the biogeochemistry of phosphorus within groundwater systems, aiming to elucidate how phosphorus interactions with other elements influence its behaviour. Our methods include chemical analyses of groundwater and aquifer materials, laboratory and field experiments, isotope analysis, and geochemical modeling.

Our findings indicate three primary processes responsible for the release of phosphorus into groundwater: apatite weathering; microbial mineralization of organic matter, which generates dissolved phosphorus as a by-product; and the reductive dissolution of iron-(hydr)oxides that serve as hosts for phosphorus. Additionally, phosphorus undergoes microbial processing during its transport, as evidenced by phosphate-bound stable oxygen isotope analysis. Phosphorus may also be immobilized by (co-)precipitation of secondary minerals (e.g., calcium-phosphates or iron minerals) or through surface adsorption. Notably, phosphorus immobilization often takes precedence over arsenic immobilization, enhancing the mobility of the latter.

The occurrence of these mobilization and/or immobilization processes largely depends on local groundwater characteristics and the aquifer's mineralogical composition. Our results highlight the intricate links between the fate of phosphorus and the biogeochemical cycles of calcium, carbon, iron, arsenic, and possibly sulphur, suggesting potential strategies for in-situ groundwater remediation approaches.

The structural integrity of geological materials are closely tied to their porosity. Accurate knowledge of microspores in potential host rocks such as Opalinus Clay is essential for assessing their physical properties, including permeability and strength. Traditional methods for porosity analysis, such as mercury intrusion porosimetry (MIP) and gas pycnometry, provide valuable quantitative data on porosity and pore size distribution but do not offer insights into pore morphology or spatial distribution.

A methodological advancement comes with the combination of broad ion beam (BIB) milling and scanning electron microscopy (SEM), which allows for the visualization of pores at the nanoscale and facilitates detailed analysis of pore structures. However, segmenting pores from BIB-SEM images poses challenges due to the complexity of the images and the variability in pore shapes and sizes. This task is further complicated by the limited resolution of SEM and the subjective nature of manual pore identification.

To address these challenges, machine learning (ML) has emerged as a useful tool for automating the segmentation of pores from BIB-SEM images. We explore the use of conditional random fields (CRFs) as an ensemble method that improves segmentation by utilizing spatial and contextual information within the images. CRFs enhance segmentation accuracy and offer a robust framework for integrating results from multiple ML-classifiers. This probabilistic approach not only refines the segmentation accuracy but also enables the assessment of uncertainty levels in segmented pores, which is beneficial for accurately interpreting the microstructural properties.

In the past years numerous machine learning based applications have been introduced to the field of seismology. These applications for example address issues such as earthquake detection, event classification, feature extraction and waveform data analysis.

In this study we focus on the denoising of waveform data by separating the seismic signal from different noise sources. Machine learning models are able to recognize noise patterns and can effectively suppress unwanted noise, enhancing the quality of the waveform signals. A deep learning based denoising autoencoder algorithm is tested on regional and teleseismic seismological and hydroacoustic datasets, which are compiled from the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organisation. We focus on seismic and hydroacoustic stations which can be relevant to investigate North Korean nuclear tests.

We investigate the performance of different denoising autoencoder models, for short- and long waveform periods, trained on the complete station network as well as on individual stations. We investigate if the denoised waveform signals are useful for seismic source analysis and if the denoised waveforms can reliably be used in further analysis steps, such as the comparison of computed array beams, seismic phase picking and or amplitude estimation.

The declared North Korean nuclear tests are a suitable benchmark test set, as they have been extensively researched and their source type and location can be assumed known. Further the verification of the source type is of particular interest for potential nuclear tests under international law.

Monitoring local seismic events is among the responsibilities of the German Federal Seismic Survey. This entity comprises a seismological subdepartment responsible for overseeing the operations of the German Regional Seismic Network and a data center tasked with collecting, archiving, and distributing continuous seismological and infrasound waveform data. As the amount of recorded seismic data dramatically increases every year, the imperative for an appropriate automatic real-time monitoring system becomes apparent. Leveraging advances in deep-learning methods in seismology, we develop a Python wrapper for the automatic estimation of hypocenter, magnitude and first-motion polarity in real time. To assess the performance of our algorithm, we compare the resulting event locations with catalogs of manually located events, with promising outcomes.

Aleatoric uncertainty, inherent in the variability of data itself, presents a significant challenge in predictive modeling, especially in scenarios with intrinsic randomness and noise. Traditionally viewed as irreducible, this type of uncertainty fundamentally limits the precision of predictions, as it is directly tied to the stochastic nature of the underlying data. However, this research proposes a methodology that combines clustering with subsequent predictive modeling to mitigate the effects of aleatoric uncertainty, thereby enhancing the transparency and reliability of model outputs. Our approach begins with a clustering process, where data points are grouped based on similarity in features to form homogeneous subsets. Following clustering, we employ quantile random forests on each subset rendering the modeling tailored to each cluster's specific characteristics. This strategy allows for the models to not only be more sensitive to the subtle nuances within a group but also more robust against the noise inherent in the dataset. Finally, we estimate heat flow over continental Africa. Through extensive quantitative analysis, this study demonstrates that while aleatoric uncertainty is indeed irreducible from a theoretical standpoint, practical interventions like quality data acquisition combined with clustering can effectively diminish its impact on predictive accuracy.

Geological mapping is essential for understanding the Earth's surface and subsurface structures, aiding resource exploration, environmental monitoring, and hazard assessment. Semantic segmentation, a computer vision technique, has shown promise in automating geological mapping processes by classifying image pixels into meaningful categories. This study explores the integration of semantic segmentation into geological mapping workflows by leveraging an artificially blended texture dataset.

Traditional geological mapping relies on extensive fieldwork in combination with manual aerial or satellite imagery interpretation, which can be time-consuming and subjective. Semantic segmentation can efficiently classify geological features by learning distinctive patterns and textures from data. However, obtaining high-quality datasets for this purpose is challenging due to the heterogeneous nature of geological formations and limited ground truth data.

We address this challenge by employing an artificially blended texture dataset that combines real-world geological textures. This blended dataset aims to enrich the training data with diverse texture and geological feature combinations, potentially enhancing the model's ability to generalize to unseen terrain conditions. Moreover, it reduces the potential for label bias by eliminating the need for manual delineation of label classes in the image, instead relying on generated borders.

Through experimental evaluation, we explore the effectiveness of semantic segmentation with the blended texture dataset in accurately delineating geological units and structures. We also discuss the implications of incorporating semantic segmentation into geological mapping workflows at the Baltic cliff coast, including its potential for improving mapping efficiency, reducing human bias, and facilitating remote sensing data integration with geological interpretations.

Machine learning approaches are increasingly used to predict groundwater levels, with local models for single monitoring wells currently being state of the art. Global models enable training and forecasting at multiple monitoring wells simultaneously, incorporating dynamic (e.g., meteorological) and static (e.g., hydro(geo)logical) features. These models can generalize predictions to wells with similar site characteristics and offer computational scaling benefits by requiring only one model for a larger area.

This study presents two global machine-learning models for short-term groundwater level prediction (up to 12 weeks): the Temporal Fusion Transformer (TFT) and Neural Hierarchical Interpolation for Time Series Forecasting (N-HiTS). The TFT combines recurrent neural networks with an attention mechanism and can determine the significance of individual input variables (feature importance). The N-HiTS model uses a fork architecture with multiple stacks to model different data frequencies, enhancing prediction accuracy.

We used a dataset of approximately 5300 monitoring wells across Germany, with groundwater levels from 1990 to 2016 (around 4.5 million values). Input features included groundwater levels, meteorological parameters, and site-specific environmental features such as hydro(geo)logical, soil, and spatial characteristics.

The TFT model showed a median NSE of 0.34, while the N-HiTS model performed better with a median NSE of 0.5 for the 12-week forecast. Around 25% of the test sites achieved an NSE over 0.68. Key features for forecast quality included historical groundwater levels, precipitation, the standard deviation of groundwater levels, and major hydrogeological districts. The topographical wetness index was the most important static feature, though its impact on model performance was minimal.

A swarm of devastating caldera-forming eruptions (>VEI 6) blanketed the Permo-Carboniferous of central Europe with voluminous pyroclastic deposits within a long-lasting period of 50 Myrs. Although of different tectonic setting, the pyroclastic record of this ignimbrite flare-up is similar to the Cenozoic deposits in the western USA, ranging from crystal-poor rhyolitic Snake River-type and compositionally zoned tuffs to crystal-rich monotonous intermediates and rhyolites.

Combined textural and chemical analysis data on whole rock, juvenile fragments (fiamme, glass shards), and mineral phases were acquired to unravel the origin and lithospheric evolution of the magma reservoirs. Two different geochemical suites can be distinguished: (I) a diopside- and (II) a corundum-normative. Examples of the diopside-normative suite are the caldera systems of Wurzen and the Wendland, as well as the vitrophyric Planitz Ignimbrite. Although all pyroclastic deposits show corundum-normative compositions; solely, the magma system of the Flechtingen Ignimbrite crystallizes almandine-garnet in a deep-seated magma chamber. In general, thermobarometric estimations suggest an interplay of hydrous near-solidus granitic systems penetrated by anhydrous SiO₂-rich superheated magmas. These systems can be tracked down to depths of 25 to 40 km (7-12 kbars) and provide insights into the post-Variscan rift-related magmatic activity.

A sudden eruption occurred in December 2022 at Lascar, one of the most popular volcanoes for tourists in Chile. Following the eruption, lava emplacement was observed in summit crater of Lascar. Due to volcanic activity and inaccessibility, we acquired a series of Pleiades tri-stereo satellite images covering this unrest episode. We generated high resolution point clouds and orthomosaics from the satellite images using photogrammetric approaches. We analyze point clouds to quantify morphological and structural details and changes. We found that the crater floor initially uplifted due to lava extrusion and rockfall deposition, and subsequently the crater floor subsided and formed a funnel in the center. To understand the mechanical factors controlling the uplift and subsidence, we designed a novel set of analogue experiments using sand-plaster mixtures to simulate lava extrusion and subsidence from same conduit. We account for topographic effects by running experiments on flat plate and 3D printed mould of the Lascar crater, respectively. We use 2D digital image correlation method to record and visualize displacements during extrusion and subsidence. The results show that extrusion and subsidence occurs along distinct shear faults, which are constrained by conduit diameter and represented as concentric fractures at surface. We develop a conceptual model that lava extrusion is affected by withdrawal from the conduit, forming a funnel-shaped surface depression associated with inward-dipping radial erosion gullies. Thus, combining satellite observations and analogue models help to identify the position and dimension of the underlying conduit, which is essential for understanding future activity of Lascar volcano.

Two diatreme structures in the Lusatian Mountains (CZ) can be assigned to so-called pre-rift period of volcanism within the Bohemian Massif. This is confirmed by Ar-Ar age determinations on intrusive ultramafic melilithic rocks in the diatremes of Dolní Falknov (≤ 68.34 ± 0.33 Ma) and Stožec (68.80 ± 0.85 Ma). Detailed geological mapping of both volcanic structures enabled to clearly demonstrate typical diatreme breccia only in the Dolní Falknov diatreme. In contrast, mapping of the Stožec volcanic structure 5 km to the northeast only revealed an intense red-brown coloured diamictite deposit. This diamictite also occurs in the top of the Dolní Falknov diatreme fill as separated clods and is interpreted as a collapse breccia. The diamictite as well as the diatreme breccia contain numerous rounded pebbles of different lithologies with diameters of up to 0.5 m. Some of these pebbles probably come from Permian rocks (Rotliegend) and indicate a multi-phase redeposition history. These could be erosion products from the Lausitz Block, which is located 2.5 and 5 km north of the two diatreme structures. The Permian sediments eroded here were later rounded off before being redeposited as terrestrial (red) sediments in the uppermost Upper Cretaceous (Campanian–Maastrichtian). These deposits have only been preserved due to their sheltered position within the pre-rift diatreme structures.

Recent discoveries and studies of maars in the NE Bavaria-Czech Republic border region have significantly expanded our knowledge of Cenozoic volcanism in the western Bohemian Massif. Using geomorphological and geophysical investigations, two new circular geological structures with partly striking geophysical anomalies were discovered: the Bärnau Maar and the Rohrloh Maar. They were explored with two scientific drillings by the Geological Survey at the Bavarian Environment Agency. Both dry maars form shallow depressions from a few hundred to approximately 1000 m in diameter. In the Bärnau Maar, a 150 m thick sedimentary sequence consisting primarily of laminated, organic-rich clayey to silty sediments with numerous diatomite laminae of a lacustrine depositional environment was drilled, with frequent sand beds and soft-sediment deformation structures documenting repeated turbidity flows and slumps. The upper sedimentary sequence comprises soft-sediment deformed lacustrine sediments overlain by gravelly and sandy deposits. The 70 m thick sediment sequence drilled in the Rohrloh Maar similarly consists predominantly of fine-grained lacustrine sediments with intercalated sandy turbidite beds. Both sediment sequences are composed predominantly of quartz-, mica-, and kaolinite-rich sediments, representing the erosion products of neighbouring crystalline rocks; however, elevated smectite contents near both core bases suggest the contribution of juvenile material. The palynological data from the Bärnau Maar and Rohrloh Maar sediments advocate a Lower to Middle Miocene age and Lower Miocene age, respectively. During this time, the climate was predominantly subtropical to temperate, and swamp forests surrounded the maars, whereas mesophytic vegetation was present in the broader region.

Regions with complex topography display a variable degree of deformation during seismic and volcanic events. In the Reykjanes Peninsula rift, both extension and strike-slip motion result from its highly oblique angle with respect to the plate opening, leading to NE- and N-striking structures, including eruptive fissure swarms, tensile fractures, normal faults and strike-slip faults. Structural domains have been explained by factors like tectonomagmatic cycles or proximity to rift axes. However, pre-existing topographic gradients were not previously considered relevant for the resulting fracture network of the area, as suggested by studies at other sites.

Following a period of uplift in the Svartsengi volcanic system, a 2-meter-deep graben formed in November 2023 due to a ~15-km long dike intrusion. In this work, we use high-resolution photogrammetric data from before and after this event to explore how Mount Thorbjorn, situated on the western part of the graben, responded to this deformation event. A Digital Elevation Model (DEM) difference map suggests tilting of the mountain towards the east and reactivation of pre-existing faults. Comparison of orthophotos before and after the event revealed new surface fractures, many corresponding to reactivated buried discontinuities, mainly expressed as normal motion and with fissures showing opening. Statistical analyses were used to test the topographic controls on the resulting faulting pattern, and sandbox analogue experiments helped better understand the process. Preliminary results suggest that the distribution of the fractures is influenced by topography, with denser patterns observed in higher elevation areas, and changes in their strike due to surface adjustments.

Hekla is one of the most active volcanoes in Iceland, with recent eruptions in 1970, 1980-81, 1991, and 2000. The last three eruptions occurred in the early months of the year when the volcano was heavily snow-covered. As a result, tephra and effusive deposits have covered large amounts of snow and ice causing an insulation effect. Using photogrammetric processing and GIS analysis of historical aerial photographs (1945-1982), recent Pléiades satellite tri-stereo images (2022 and 2023), and UAV data acquired during the 2022 and 2023 fieldwork, we found evidence of intense cryospheric processes such as rock glacier emplacement and multiple thermokarst formations. Our results show that the NW flank of Hekla is covered by 6 distinct rock glacier lobes that were recently (after 1982) emplaced atop previously formed rock glaciers identified in 1945-1982 datasets. The total area of the recent rock glaciers is about 2 km². The longest lobe reaches 1.4 km in length and has a 50 m front thickness. The lobe has advanced by 13 m over 1 year (2022-2023). The newly emerged thermokarst sinkholes have been observed in the field in the summit area and on the NE flank. These aspects of Hekla's evolution may play a significant role in the magnitude of hazards in case of future unrest. The emplacement of lava along rock glaciers and permanent snow raises the risk of impending lahars. Volcanic heat can expedite permafrost degradation and the advancement of rock glaciers, culminating in significant landslides.