Buckle folding in the Northern Calcareous Alps - Field observations and numeric experiments

Thrust tectonics in the Wetterstein and Mieming mountains, and a new tectonic subdivision of the Northern Calcareous Alps of Western Austria and Southern Germany

“…Considering relative ages, the Höll shear zone and the ESE-to E-trending folds are contemporaneous. If the kinematic connection between NW-transport of the western Inntal thrust sheet and the Höll shear zone is accepted, the ESE-to E-trending folds of the Wetterstein and Mieming mountains grew during the Upper Cretaceous, and the divergence of fold axis orientations can be explained by strain partitioning across the Höll shear zone as already suggested by Ortner and Bitterlich (2016) and Kilian et al (2021). Growth of the NCA orogenic wedge by thrusting and folding only SW of the Höll shear zone would be difficult, as Cenomanian to Campanian (Weidich 1984) growth strata in synorogenic sediments N of the Wetterstein mountains (10 of Fig.…”

“…This observation is in contrast to the tectonic evolution of the Austroalpine basement units, where Late Cretaceous stretching separates Cretaceous and Cenozoic shortening (Froitzheim et al 1994;Neubauer et al 1995;Fügenschuh et al 2000). This event has not been observed in any of the more recent studies on the tectonic development of the NCA (May and Eisbacher 1999;Auer and Eisbacher 2003;Tanner et al 2003;Behrmann and Tanner 2006;Kilian and Ortner 2019;Oswald et al 2019;Kilian et al 2021), except Froitzheim et al (2012. During the Miocene, renewed NNE-to NE-directed shortening affected the NCA (Decker et al 1994;Ortner 2003b) that was largely related to activity of strike-slip faults and contemporanous to postcollisional transport of the Alpine wedge into the Cenozoic foreland basin on the European margin (Ortner et al 2015;Schuller et al 2015).…”

“…This applies for the Karwendel mountains as well (traces of fold axial planes 2, 3, 4 of Fig. 7a; see also Heißel 1978;Kilian and Ortner 2019;Kilian et al 2021). NW of Telfs, the Höll shear zone is truncated by the Telfs fault (T of Fig.…”

“…The Tannheim thrust sheet is also exposed in some windows in the more internal part of the NCA, like the Puitental window between the Mieming and Zugspitze thrusts, and the Eng Window between the Karwendel and Eng thrusts (Fig. 17), where the Tannheim thust sheet was exhumed by duplexing in response to Late Cretaceous erosion (Kilian et al 2021).…”

Oblique basin inversion leads to fold localisation at bounding faults: Analogue modelling of the Achental structure, Northern Calcareous Alps, Austria

“…Lithotypes consist of lagoonal, reefal and forereefal lime-and dolostones with a fossiliferous content of e.g., stromatolithes, oolites, calcareous algae and sponges; (Sausgruber 1994a) and their fragments. Although the Alpine Muschelkalk Group and Wetterstein limestone show a general thickness between 1000 to 120 >2200 m in the Achensee region (Sausgruber 1994b;Nagel et al 1976;Gruber et al 2022), cross sections in Gruber et al (2022) show a thickness up to 3500 m. These thickness variations are attributed to salt tectonics in the Triassic (see Ortner and Kilian 2022;Granado et al 2019;Kilian et al 2021). The Carnian Raibl event marks the abrupt termination of carbonate sedimentation on the Wetterstein platform (Hornung et al 2007;Krainer et al 2011).…”