Establishment of the Upper Permian Mujiu Co Formation and rugose coral assemblage in the Xainza area, northern Tibet

The authors found an up to2348m thick sequence consisting dominantly of dolomite and dolomitic limestone.This sequence lies conformably on the Lower Permian Xiala Formation and contains at its base important elements of the early Late Permian coral fauna of southern China,such as Waagenophyl-lum indicum crassiseptatum Wu and Liangshanophyllum streptoseptatum H.C.Wang,in addition to their associated elements Lobatophyllum zakangense S.Z.Wu and Waagenophyllum megacolumetum.All these ele-ments combine to form a rugose coral assemblage characteristic of the early Late Permian,named the Waagenophyllum-Liangshanophyllum-Lobatophyllum.The authors establish a new formation-Mujiu Co Formation-with the sequence dominantly of dolomite and dolomitic limestone containing this coral assem-blage.This formation is stratigraphically equivalent to the Upper Permian Wujiaping Formation in southern China.