Metamorphic history and monazite age of pelitic gneiss in the Lhenice shear zone (Moldanubian Zone of the southern Bohemian Massif).

Abstract

Multiple equilibrium stages were identified from Grt-rich gneiss in Lhenice shear zone (southern Bohemian Massif). The geothermobarometory gives following P-T conditions: 1.5-2.3 GPa at 700-900 ^oC for Grt-core (Stage 1), 730-830 ^oC and 1.0-1.3 GPa for Grt-rim (Stage 2), and 740-850 ^oC and 0.6-0.8 GPa for matrix (Stage 3). To evaluate age of multiple equilibrium stages, CHIME age dating was carried out. The monazites which included in the Grt-core give 337+/-4.3 Ma. The monazites which included in the Grt-rim give 335.4+/-7.2 Ma. The monazites in matrix give 334.9+/-3.9 Ma. These results suggest that the studied rock experienced very fast exhumation.