Orogen-parallel strike-slip faults bordering metamorphic core complexes: the Salzach–Enns fault zone in the Eastern Alps, Austria

Abstract

The approximately ENE-trending Salzach–Enns fault (Eastern Alps) contributed to late-stage exhumation of the Tauern metamorphic core complex in response to oblique convergence of European and Adriatic plates. Six stages of kinematic evolution with early ductile and later brittle deformational structures were recognized as follows: (1) Initial ductile deformation is represented by a combination of sinistral shear-dominated noncoaxial strain and coaxial strain. (2) Early brittle sinistral strike-slip is combined with a pure shear deformation and represents roughly N–S contraction. It is followed by (3) sinistral strike-slip and (4). ca. N–S extension due to normal-slip striations. (5) Subsequent N–S compression resulted in counterclockwise rotation of the maximum principal stress from NE to NW and led to final dextral strike-slip displacements along the Salzach–Enns fault. The exhumation of the Tauern Window was accommodated by dip-slip on the fault plane at shallow levels and coaxial flattening at deeper structural levels. Brittle sinistral faults at shallow structural levels produced a larger amount of strike-slip displacement than ductile shear zones at the deeper structural levels, which is explained as a scissors-like movement and which resulted in the eastward tilting of the Tauern Window.