Petrological Characteristic And Provenance Analysis Of The Trassic Bayan Har Group In Gander, Qinghai Province

The study area is located within the Bayan Har Sub-Orogen of the Triassic Songpan-Ganzi Orogen in the northeastern Tibetan Plateau,and it is joined with the West Qinling orogenic in southwest,purpose of the study is to explore Petrological characteristic and provenance analysis of the Trassic Bayan Har Group in Gander,Qinghai Province. Songpan-Ganzi orogenic belt is evolved from the consumption of a Paleo-Tethys passive margin orogenic belt,it is formed on the final closure of Paleo-Tethys and Qiangtang, Kunlun, North China and the Yangtze in the continental collision process. Bayan Har Group of Qinghai Gander is characterized by Triassic strata widespread,it is a suite of arenopelitic flysch- type flysch deposits,the main rocks of study area are lithic sandstone and feldspar sandstone,these are mostly neritic facies- abyssal facies turbidity current. depositional environment. Bayan Har Triassic sedimentary basin from east to west,from bottom to top having a trend that passive continental margin to active continental margin, continental or oceanic island arc evolution trend.The main rocks of the study area are lithic sandstone and feldspar sandstone,determination of major and trace elements of the study area samples,Si O2 content ranged from 57.09% ~ 73.76%,structural environment of the study area in the Triassic period was mainly continental island arc,followed by active continental margin and passive continental margin,had no oceanic island arc. Eu has negative abnormity,(La/Sm)N mean: 4.03;(La / Yb) N Mean: 10.63,ΣLREE>ΣHREE. The U-Pb ages of LA-ICP-MS of detrital zircon concentrated in 190-558 Ma,787-1144 Ma,1488-2590 Ma,more consistent with the Yangtze block and South Qinling orogenic belt, and detrital zircon Hf isotope characteristics tend to the Yangtze block and South Qinling orogenic belt,significantly associated with the North China Block and Qiangtang characteristics of different, so the source area of Qinghai Gander area mainly based the Yangtze block and South Qinling orogenic belt.