Palaeobiogeographical analysis of the Mississippian (early Carboniferous) brachiopod fauna in the Tibetan Plateau

The Tibetan Plateau comprises several allochthonous terranes/blocks originated from the northern margins of eastern Gondwana. Brachiopod faunas from different terranes were referred either to Gondwana province or Cathaysia province through the Late Palaeozoic. They are very important in studying the palaeobiogeography regarding the early development of the Palaeotethys Ocean. However, due to tectonic complexity and uneven research in fossil groups through time, the palaeobiogeographical connections and geodynamic history of these terranes in the Mississippian (early Carboniferous) remain ambiguous. In this study, the brachiopod dataset was compiled and reviewed at three critical intervals in the Mississippian (Tournaisian, early Vise ' an, and late Vise ' an), based on material from 13 sections in the Tibetan Plateau (the Himalaya, Lhasa, North Qiangtang, and Qamdo) and those from adjacent areas in the Qaidam terrane, Baoshan terrane, Kashmir, Alborz Mountains, and western Australia. We utilized a community detection approach from network theory that incorporates presence-absence patterns of brachiopod genera. The results demonstrated increasing provinciality and endemicity through Tournaisian-Vise ' an, and supported a trend for the North Qiangtang and Qamdo terranes from the transition zone in the Tournaisian and early Vise ' an to a station far from the northern Gondwana margins since the late Vise ' an. This evidence further proves that the Longmu Co-Shuanghu suture zone serves as an effective palaeobiogeographic barrier and represents the main branch of the Palaeotethys Ocean during the Mississippian. The remarkable palaeogeographical reconfiguration represented by the significant palaeobiogeographical frag-mentation appropriately indicates a moderate to low palaeolatitude for the North Qiangtang and Qamdo terranes regarding a persistently widening eastern Palaeotethys Ocean in the late Vise ' an.

Automated summary

By studying the brachiopod faunas from different terranes in the Tibetan Plateau, it was found that there was an increasing trend of provinciality and endemicity in the Mississippian period. Additionally, the Longmu Co-Shuanghu suture zone was identified as an effective palaeobiogeographic barrier during this time.