EGU2012-7764.pdf

The Matsch Unit in the Austroalpine crystalline basement of the Eastern Alps experienced three tectonometamorphic events: Variscan amphibolite-facies metamorphism, a Permian low-pressure event, and a Cretaceous greenschist-facies metamorphic overprint. This study compares deformation and reaction microstructures in high- and low-strain domains of Cretaceous deformation affecting Permian pegmatites and metapelitic host rocks. Microfabrics show dynamic recrystallization of quartz and feldspar, with lattice preferred orientation and bulging recrystallization indicating Cretaceous deformation. Pre-Cretaceous microfabrics are characterized by medium to coarse grained recrystallization without a clear lattice preferred orientation. The study aims to investigate the effects of Cretaceous deformation on the Rb-Sr isotopic system of biotite, white mica, and feldspar to better understand the interrelation of strain and isotopic re-equilibration in deformed, polymetamorphic rocks.