Zircon U-Pb geochronology of the Baishahe Formation in the western part of East Kunlun Orogenic Belt: Constraints on Precambrian basement evolution

The geochronology of the detrital zircons of the gneiss in the Aquedun region, western part of the East Kunlun Mountains was studied by LA-ICP-MS method.The ages of the detrital zircons of the gneiss vary between 2400 Ma and 410 Ma with a peak ranging from 1650 Ma to 1400 Ma.Minor metamorphic zircons was dated as 1.0~0.9 Ga (Neoproterozoic) and 410 Ma (Early Paleozoic).The dating results imply that the protolith of the gneiss was deposited in Late Mesoproterozoic, and had undergone Neoproterozoic and Early Paleozoic metamorphism.Based on eclogite in gneisses formed in Early Paleozoic (450~410 Ma).Combined with a lot of Early Paleozoic metamorphic information from zircons in gneiss, it is speculated that the gneiss in this region also underwent Early Paleozoic eclogite-facies metamorphism, and gneiss and eclogite is in situ relationship.Combined with regional studies, it is suggested that there may exists a high pressure metamorphic belt of nearly 1000 km long in Early Paleozoic in East Kunlun, which may be the product of subduction and reentry.