A new late Kungurian (Cisuralian, Permian) conodont and fusuline fauna from the South Qiangtang Block in Tibet and their implications for correlation and paleobiogeography

A late Kungurian (Cisuralian, Permian) fauna including conodonts and fusulines is reported for the first time from the limestone units in the lower part of the Lugu Formation in the South Qiangtang Block (SQB) in Tibet. The conodonts include Mesogondolella siciliensis, M. qiangtangensis sp. nov., Sweetognathus subsymmetricus and S. guizhouensis. They all consistently indicate a late Kungurian age. The associated fusulines in the same interval include Armenina asiatica, Neoschwagerina simplex, Pseudodoliolina ozawai minima and Cancellina sp., which reliably indicate a Murgabian age. The coexistence of these conodonts and fusulines provides direct correlation between the base part of the Murgabian Stage in the fusuline-based Tethyan timescale and the late Kungurian Stage in the conodont-based international timescale. The conodont species S. subsymmetricus and S. guizhouensis together with the associated fusulines and brachiopods generally indicate a warm condition when the Lugu Formation was deposited, therefore, the SQB had incorporated into the equatorial warm water province during the late Kungurian. This contrasts with coeval cool water Vjalovognathus fauna from the basal part of the Xiala Formation in the Lhasa Block, the lower part of the Moulmein Limestone in the Hpa-An area in southern Myanmar and the Wandagee Formation in Western Australia. In addition, typical warm water Tethyan fusulines are absent in the Lhasa Block in the equivalent strata. These distinct faunal differences suggest that a wide Bangong-Nujiang Ocean between the SQB and the Lhasa Block probably existed during the late Kungurian.