Early Carboniferous blueschist facies metamorphism in metapelites of the West Sudetes (Northern Saxothuringian Domain, Bohemian Massif)
Abstract
The metamorphic evolution of micaschists in the NE part of the Saxothuringian Domain (SD) is characterized by the early HP assemblage with cld in cores of garnet and Grt-Chl-Phe-Qtz-Pg ass. in the matrix. Minerals of M1-M2 stage were overprinted by LP assemblage Ab-Chl-Ms-Qtz-Ep.Thermodynamic modelling suggests that mineral ass. record peak-P conditions of >=18-19kbar at 460-520°C followed by decompression 10.5-13.5kbar and final decom. to <8.5kbar and <480°C.The peak PT indicate a HP/LT thermal gradient of 7-7.5 C°/km.Laser ablation ICP-MS isotopic dating and el. microprobe dating of monazite from the M1-M2 mineral assemblages give ages of 330+/-10 and 328+/-6Ma,which are interpreted as the timing of a peak pressure to early decompression stage.The met. record and timing of metamorphism show striking similarities with the evolution of the central and SW parts of the SD and suggest a common tectonic evolution along the eastern flank of the SD during the Devonian-Carboniferous periods.