Zircon U-Pb Age And Tectonic Setting Of Permian-Triassic Volcanic Rock In East Kunlun Orogenic Belt

The East Kunlun Orogenic belt locates at the joint region between the North China and South China plate, and which has been formed by multi-period, such as Caledonian and Indo-China period orogenic movements. Its complex tectonic evolution history makes it as a typical complex orogenic belt, which contains lots of important geological information and has been the key study area and focus for the worldwide geologists for many years.This thesis studies the Permian-Triassic volcanic rocks which were outcroped at the north of Xiugou basin, East Kunlun Orogenic belts. Based on the plate tectonic and collision orogenic theory, geochemical analysis and zircon U-Pb dating methods, the geochron of the stratum and tectonic setting are systematically discussed.Based on research and discussion above-mentioned, obtained the following conclusion:1) The results of zircon U-Pb dating show that the age of the stratum locates between Dongwenquan and Hongshishan is late Permian (252-261 Ma) Which was formerly considered as middle-late Triassic, and the Naocangjiangou Formation should be later early-middle Triassic, may not be middle Triassic.2) The geochemical analysis results show that the Permian-Triassic volcanic rocks generated in a typical island arc setting.3)The geochron and tectonic setting of volcanic rocks, together with the previous results sugget that East Kunlun Orogenic Belts underwent three stages during the tectonic evolution from late Plaeozoic to early Meszoic: oceanic spreading and rift formed stage (C-P2), the plate subduction stage (P3-T2) and continent-continent collision stage (T2-J1).