EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

A large-scale detachment system in the central Eastern Alps (Upper Austroalpine Unit, Austria)

Manuel Werdenich1, Christoph Iglseder3, Bernhard Grasemann1, Gerd Rantitsch2, and Benjamin Huet3
Manuel Werdenich et al.
  • 1Department of Geodynamics and Sedimentology, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria (*
  • 2Department of Applied Geology and Geophysics, Montanuniversität Leoben, Peter-Tunner Straße 5, A-8700 Leoben, Austria
  • 3Department of Hard-Rock Geology, Geological Survey of Austria, Neulinggasse 38, A-1030 Vienna, Austria

Based on new structural field data and Raman micro-spectroscopy on carbonaceous material a major detachment juxtaposing Drauzug-Gurktal Nappe System (DGN) against the transgressive Permo-Mesozoic cover sequence of the Ötztal-Bundschuh Nappe System (BN, Stangalm Mesozoic s. str.) in the area SE of Flattnitz (Carinthia, Austria). An Eo-alpine top-SE kinematic has been identified.

The hanging wall unit comprise lithologies of the DGN phyllites, conglomerates and graphite schists (Stolzalpe nappe), which have experienced only low grade greenschist deformation. Raman constrains 350°C±40°C.

The footwall unit consists of dolomitic ultra-mylonites, calcitic marble mylonites, meta-conglomerates and quarzites (Stangalm Mesozoic and Kuster nappe), which have experienced at least four main deformation phases. The oldest structures (D1) corresponding to Eo-Alpine nappe stacking are overprinted by (D2) isoclinal recumbent folds with E-W oriented shallow dipping fold axis and an axial plane schistosity, dipping shallowly to WSW. Ductile to brittle-ductile top to the E shearing (D3) is indicated by ESE-trending stretching lineation, C-type shear bands, stylolites, crystal- and shape preferred orientations of mineral grains. Late brittle deformation (D4) is recorded in steep joint sets with dip-directions to NW. Raman constrains 480°C±40°C.

The detachment zone comprises a complicate zone of high strain including units from DGN folded together within the Stangalm Mesozoic, which have experienced the same deformation as the BN.

How to cite: Werdenich, M., Iglseder, C., Grasemann, B., Rantitsch, G., and Huet, B.: A large-scale detachment system in the central Eastern Alps (Upper Austroalpine Unit, Austria), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19144,, 2020