Early metamorphic evolution and exhumation of felsic high-pressure granulites from the north-western Bohemian Massif

Abstract

Several granulite terrains are exposed in the Bohemian Massif of Central Europe. These were metamorphosed at pressures close to 12 kbar and temperatures of more than 800 °C c. 340 Ma ago. The corresponding penetrative deformation almost totally erased the record of the preceding metamorphic evolution. Nevertheless, rare relics such as mineral inclusions in large garnet grains are witness of this earlier evolution, which was previously related to significantly higher pressures and, thus, to a subduction-related event. The exemplary investigation of such mineral relics in a felsic granulite from the Granulitgebirge rather points to pressures of 13–14 kbar only at relatively low temperatures of 620 °C and, thus, to considerable, nearly isobaric heating before the exhumation of the granulites started at 800 °C or somewhat higher temperature.