Discovery of Permian and Triassic conodonts in the Shiquanhe area, Ngari, western Tibet, China and their significances

Conodonts are discovered in the Angjie, Xiala and Zuozuo formations in the Shiquanhe area, Ngari, western Tibet. The conodont assemblage in the Angjie Formation is roughly correlated to the Middle Permian early-middle Kungurian Mesogondolella idahoensis-Vjalovognathus shindyensis Assemblage Zone, the conodont assemblage at the uppermost part of the Xiala Formation is roughly correlated to the Late Permian late Changxingian Clarkina changxingensis Zone. The Early Triassic conodonts Neospathodus sp. and Gladigondolella sp. are found in the Zuozuo Formation, which conformably overlies the Xiala Formation; therefore the age of the main part of the Zuozuo Formation is Triassic. The transition from the Gondwanic clastic sediments to Tethysian carbonate sediments in the Shiquanhe area started from the terminal Early Permian, and during the Late Permian Changxingian Stage and Early Triassic the Shiquanhe area still remained in a marine environment. So the view that western Gangdise was a land during the Late Permian and Triassic should be reconsidered.