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Structural geological investigations and stress field analysis in the western Vorderer Bayerischer Wald

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

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

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

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

Details

Author
Sophia Methner1, Bastian Wauschkuhn1
Institutionen
1Geologischer Dienst, Bayerisches Landesamt für Umwelt, Germany
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/1x72-vb18