Lower–Middle Triassic conodont biostratigraphy and evolution from South Tibet, China: Implications for global correlations

Conodonts have played important roles in Triassic biochronology, providing a robust timescale for deciphering the mechanisms and patterns of the Permian–Triassic mass extinction and its subsequent recovery. Studies of Early–Middle Triassic conodonts in South Tibet are relatively scarce and lack high-resolution conodont biostratigraphies. In this study, we have presented 12 interval zones based on the collection, including 58 species in 16 genera of conodonts from three sections (Selong, Xialong and Gyanyima) in South Tibet. The Clarkina taylorae Zone, Neoclarkina krystyni Zone, Novispathodus pingdingshanensis Zone, Triassospathodus homeri Zone, and Nicoraella germanica Zone were first reported in South Tibet. In combination with previous work from the Neotethys, 12 Unitary Association zones (UAZs), comprising two Griesbachian, two Dienerian, four Smithian, and four Spathian UAZs, were recognized, seven of which were documented within South Tibet. Based on the new data from South Tibet, we have identified six stages in the evolution and diversification of the Early Triassic conodonts. Combining the new conodont biozones with published ammonoid UAZs and carbonate isotopic profiles provides a robust integrated Early Triassic stratigraphy, which enabled a more precise definition of the Induan–Olenekian boundary within the Neotethyan realm.