The determination of the age of Jiayuqiao Group in northern Gangdise of Tibetan Plateau

Abstract：The formation age of Jiaoyuqiao Group, i.e., the metamorphic rocks in the northern margin of Gangdise, is still in controversy. High resolution LA-ICP-MS in situ U-Pb analysis was conducted for the intercalation of garnet-bearing green schist in marbles of upper Jiayuqiao Group at Bajian Village, Baxoi County, Tibet, and an upper intercept age of 566±27 Ma was obtained. This result cinfines the formation age of the Jiaoyuqiao Group to late Sinian. Combined with related data, the authors hold that there existed a large continental margin rift in the northern margin of Gangdise in late Sinian-Cambrian period.