Redefinition of High Pressure Metamorphic Rocks from West Kunlun Orogen and Its Tectonic Significance

A set of "Grt-Pl-Hbl gneiss and Sil-Grt-Bit-Pl gneiss" has been disintegrated from the eastern part of Tashkurghan area in West Kunlun.According to the geochemical characteristics study, the Grt-Pl-Hbl gneiss was derived from basic volcanic rocks, with the features of island-arc basalt.In the discrimination diagram, their samples are plotted in the field of island-arc basalt.The Sil-Grt-Bit-Pl gneiss was sourced from clastic rocks.In the discrimination diagram, their samples are plotted in the active continental margin and in the continental arc.According to the isotope chronology, the Grt-Pl-Hbl gneiss was formed in early Cambrian epoch.Since the formation of magma, the Grt-Pl-Hbl gneiss has experienced four notable thermal events in Silurian, Permian, Cretaceous and Miocene.The redefinition of high pressure metamorphic rocks in this area has a great significance to discussing the tectonic evolution in West Kunlun.