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Fault sets in the North Alpine Foreland Basin in Bavaria and their relation to subduction processes in the Alps

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

Details

Author
Martin Elsner1
Institutionen
1ERDWERK GmbH, Germany
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/cxrh-as65
Geolocation
Central Europe