Paleozoic To Mesozoic Magmatic Evolution And Sedimentary Dispersal History Of The Eastern Kunlun Arc,Central Tibetan Plateau

The evolution of the Kunlun arc is central to the reconstruction of the Paleo-Thethys evolution in Asia.To understand the magmatic and tectonic events in the Eastern Kunlun Range,the paper presents an investigation and analysis of the geologic structures of the area and LA-ICP MS zircon U-Pb dating of Paleozoic and Mesozoic magmatisms of granitoids in the basement of the Eastern Kunlun Range on the basis of 6 granitoid samples collected from the East Kunlun Mountains.According to the results in this paper,the basement of the East Kunlun Mountains,has experienced two minor periods of intrusive activities of granitoids since the Early Paleozoic,which are the magmatisms occurring in the Late Cambrian-Devonian(stage I),and the Late Permian-Middle Triassic(stage ?),with the peak ages in the range of 400-450 Ma and 220-280 Ma,respectively.Among them,we find a granitoid gap from 330-390 Ma and the Late Permian-Middle Triassic granitoids form the main components of the basement of the region.The geochemistry data from magmatic rocks can be used to characterize the origin and the tectonic setting.These granitoids geochemistry results are consistent with that the tectonic evolution is probably a process of collision to intraplate-rifting during the Early-Middle Paleozoic to Late Traissic time.The Late Carboniferous-Early Permian volcanic rocks were also formed in a subduction setting.We also got the Late Carboniferous-Early Permian volcanic rock yielded U-Pb inherit zircon age probability peak?2430Ma,is typically used to define a North China block(NCB)zircon signature.In order to define provenance signatures of the Eastern Kunlun region and the effects of its sediment-transport processes on them,we carried out coupled U-Pb dating analysis on five sandstone samples from the Eastern Kunlun Range.We also quoted three samples from our early work to complement our results in this study.And the results show that detritus was sourced the proximal derivation of these strata from the Kunlun arc.According to petrographic observation for two sandstones.we found that they are plotted within the provenance of the boundary between the recycled orogen and the dissectd magmatic arc.This implies relatively more detritus contributed from the Himalayan orogen and magmatic arc where batholithic boots might be exposed.We raise the possibility that there were a big river flowing from Gangdese Shan northward to the Qaidam basin prior to the uplift of the Eastern Kunlun Shan,bringing in 120 Ma zircon grains to this area,but we don't exclude the West Qinling as possible provenance.We suggested three competing processes during the Ordovician to Traissic time(220-450 Ma)to interpret the granitoid gap in this region.i.e.rifting model,erosion model and subduction model.The U-Pb geochronologic data provide important constraints on the development history of the Kunlun arc,the Qilian arc and the Qinling arc.We raise the possibility that the forming time of three magmatic arcs is almost simultaneously,early to middle Paleozoic.However,our U-Pb detrital zircon data suggest that Kunlun arc terrane provides a detrital zircon signature that is unique from that of the Qinlin and Qilian region.