A new Permian-Triassic paleogeographic reconstruction for the East Asian blocks

The East Asian blocks were important parts involved in Pangea formation, and their paleogeographic evolution during the late Paleozoic was controlled by two tectonic domains: the Paleo-Asian Ocean (PAO) and the East Paleo-Tethys Ocean (EPTO). Although some tectonic reconstructions of East Asia have been proposed, there has been a great contradiction between them and paleobiogeographic models during Permian. We have recently complied the Permian-Triassic East Asian paleomagnetic database and reconstructed the paleogeography of East Asia in combination with paleontological (e.g., data from the Paleobiology Database) and geological evidence. The new reconstruction for the East Asian blocks exhibited that the Xilinhot-Songliao Block was located between the eastern PAO and the EPTO during the early Permian and was the intermediate unit that separated the two tectonic domains. The Paleo-Tethys Ocean was a wider east-west range than most previous version. It strongly supports Torsvik et al. (2008)’s view that the absolute paleogeographic position of the South China Block reconstructed by the eruption of the Emeishan large igneous province (~260 Ma) at the margin of the Large Low Shear wave Velocity Provinces. During 265-255 Ma, the East Asian blocks moved rapidly northward, which probably accelerated the end‐Guadalupian mass extinction in East Asia. The PAO closed completely at 250 Ma, and thus the tectonic framework of the Northeast Asian continent was basically formed. Since then, East Asia began to transform into a new evolutionary stage of the superposition of multiple tectonic regimes: (1) the north Mongol–Okhotsk Ocean (between Siberia and Amuria) had sustained scissor-like closure from west to east during the Mesozoic period; (2) the east Paleo-Pacific oceanic plate had undergone westward successive subduction and accretionary since the early Mesozoic (e.g., formed the Nadanhada accretionary terrane and the Sikhote orogenic belt); (3) the southwest Tethyan blocks (e.g., North/South Qiantang, Lhasa, Indochina, Sibumasu) experienced a rapid northward movement accompanied by intense subduction and collision.