Tectonic history of East Asia and the Asiana hypothesis

Douwe J.J. van Hinsbergen , Shihu Li, Zhenyu Li, Bram Vaes, Peter Lippert, Ruiyang Chai, Bitian Wei, Teng Wang, Grant Rea-Downing, Douwe G. van der Meer, Alexis Licht, Nalan Lom, Pietro Sternai , Yanan Zhou, Chenglong Deng, Bo Wan, Wim Spakman , Ding Lin

When almost all continents were assembled in the late Paleozoic supercontinent Pangea, East Asian continental blocks existed as distinct, separate entities. Ocean closures and stepwise assembly of these blocks into larger continents were the main paleogeographic changes to influence paleoclimate and biogeography during Pangea time. In this Perspective, we review how Triassic assembly of the East Asian blocks formed the only major continent, the size of South America, that was never part of Pangea: we name this continent Asiana. To quantify its paleogeography, we computed site-level based paleolatitude paths based on an up-to-date paleomagnetic database. Asiana formed in the Northern Hemisphere (sub)tropics, bounded in the south by the Mesotethys and in the north and west by the Mongol-Okhotsk-Waser ocean. Asiana then traveled 2000-3000 km towards 'Eurussia' in the early Cretaceous, forming Eurasia. Puzzlingly, absence of a widespread geological record of intracontinental shortening suggests that this convergence closed the Mongol-Okhotsk-Waser ocean at a sparsely identified suture, yet Asiana dinosaurs suggest that transient Triassic and Jurassic land bridges must have existed: their locations remain unconstrained. Subduction remains of Asiana’s assembly and evolution are seismically imaged as the deep-mantle 'slab graveyard' below Asia. The Asiana hypothesis affects paleoceanography and paleoclimate, biogeography, and geodynamics, and requires field mapping to unravel its approach to and collision with Eurussia.