High-pressure metamorphism and exhumation rates, Eclogite Zone, Tauern Window, Austria

The age of high-pressure metamorphism in the Penninic units of the Tauern Window has up to recently been unknown, and no exhumation rates were available. In this DFG-funded project, we aim to date both high-pressure metamorphism and different exhumation-related metamorphic stages by Rb-Sr multimineral and U-Pb methods. Such data are required to determine exhumation rates, to get better constraints on the dynamics of deep exhumation, and to understand the syncollisional geodynamic evolution of the Eastern Alps. First results indicate that at 31.5 Ma (Oligocene), eclogite was formed at depths close to 90 km, and then rapidly exhumed in an extrusion wedge, with plate-tectonic rates exceeding 36 mm/a. The 31.5 Ma time mark also sets a starting point for the evolution of the Tauern Window. Extrusion-wedge exhumation started contemporaneously with extensional and strike-slip deformation, processes which lead to exposure of large areas of mid-to lower crustal Penninic lithologies in the Tauern Window until the Middle Miocene.

 

• Contact:  Dr. Johannes Glodny