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.