Origin of felsic granulite microstructure by heterogeneous decomposition of alkali feldspar and extreme weakening of orogenic lower crust during the Variscan orogeny
2011
Abstract
This paper answers the question of origin and evolution of a granulitic microstructure typically developed in felsic granulites of the European Variscan belt. It shows that the precursor of the Variscan felsic granulites was a high-pressure alkali feldspar-rich coarse grained layered orthogneiss.
During exhumation and decompression, the fine grained matrix underwent viscous deformation, forming the typical microstructure of the Variscan granulites. It switched to dislocation creep mechanism and a general hardening of the granulites under amphibolite facies conditions.