Origin of the Songpan-Garze Terrane on the northeastern Tibetan Plateau, eastern segment of the Tethyan tectonic domain: A Middle Permian−Early Triassic intracontinental rifting system

The initiation of a continental rift or the birth an oceanic basin, and their long-term evolution, are challenges in understanding evolution regional global tectonics. Rifts develop within interior margins plates, essentially as extensional structures, they have been studied widely since discovery plate eastern segment Paleo-Tethys traversed central Asia, its structural features, timing, geological setting, geodynamic mechanisms poorly understood. Songpan-Garze Terrane (SGT) on northeastern Tibetan Plateau has regarded either remnant Ocean basin. Different interpretations SGT lead to various tectonic reconstructions between Gondwana Laurasia. Here, sedimentology, geochemistry, geochronology applied southern northern parts reconstruct Permian system. In this area, for first time, field investigation reveals that is characterized by continuous succession Permian−Lower Triassic terrestrial-neritic deposits ocean island basalt (OIB)-type basalts, it developed intracontinental basin Yangtze Block. Zircons from gabbros with OIB-type geochemical signatures intruded yield U-Pb ages 263−254 Ma, constraining timing initial rifting. Proterozoic felsic rocks collected 761−865 petrologically geochemically comparable Neoproterozoic basement along western margin Middle−Late volcano-sedimentary sequences geochemistry Panxi region Thus, proposed originated Block during Middle Permian−Early Triassic, continued deepen through Triassic.