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The Cenozoic structural history of the Fichtelgebirge, Bavaria – new constraints from field observations

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.

Details

Author
Tobias Eberlei1, Torsten Hahn1
Institutionen
1Bayerisches Landesamt für Umwelt, Germany
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/mnf8-4d95