Abstract
The western Tauern Window of the Eastern Alps constitutes a mature
transpressive wrench zone generated by Oligocene-Miocene convergence
between the Dolomites Indenter and the European foreland. As a major
structural divide, it translates convergence-parallel north-south
shortening into convergence-perpendicular eastward lateral extrusion.
About 7000 foliation, lineation, fold-axis, axial-plane, shear-zone, and
shear-band measurements at ~1800 sites detail the
structural geometry and evolution during indentation and transpression,
modeled by numerical and analogue-material experiments. The results
outline the western Tauern Window as an orogen-scale zone of localized
deformation, consisting of tight, upright folds, reactivated by a
sinistral shear-zone network. It connects the Giudicarie Belt southwest
of the indenter salient with the Salzach-Ennstal-Mariazell-Puchberg
Fault (SEMP) in the northeast. This transpressive zone has a sigmoidal
vortex geometry, decoupling the Ötztal Basement in the west from the
extruding wedges of the Eastern Alps in the east. Shortening was
successively absorbed by nappe stacking, upright folding, and dome
formation and then maintained by transpressional shearing that led to
lateral extrusion, probably promoted by a change in the lithospheric
configuration. The western part of the SEMP likely rotated ≥20°
clockwise around a pole approximately halfway along its entire length
during the indentation.