Abstract:
The proto-East Asia continent was build up through Triassic Indosinian orogenesis. Its surrounding three oceans, the Paleo-Pacific ocean to the east, the Mongolian-Okhstk ocean to the north, and the Meso Tethys to the southwest, were quasi-simultaneously subducted under this continent in the earliest Jurassic, which marked the beginning of a new tectonic era called East Asia multi-plate convergence history or for short East Asia convergence. In this paper, by integrating the recent research results of tectono-magmatic studies, we briefly describe the basic features of the three marginal tectonic belts generated by the East Asia convergence, i.e., the Mongolia-Okhstk collisional orogen along its northern margin, the subduction-related accretional orogens along its eastern margin, and the Bangonghu-Nujiang suturing zone along its SW margin, together with widely developed compressional and extensional structures and magmatism produced in the interior of the East Asia continent. A new chronology of the tectonic evolution history was established in which three distinct stages were separated. The Early Jurassic (200~170 Ma) was dominated by coeval landward subduction of the oceanic plates and the development of active continental margins and magmatic activity along the marginal zones. The Middle-Late Jurassic to Early Cretaceous (170~135 Ma) was characterized by the structural development of three marginal orogenic belts (subduction-related accretional and continent-continent collisional orogenesis) and intra-continental orogenic zones, which, as a whole, formed the East Asia convergent tectonic system. The Middle-Late Cretaceous (135~80 Ma) was predominated by crustal extension and lithospheric thinning, with the development of continental extensional tectonic system in East Asia, due in part to the demise of the Mongolia-Okhstk orogeny, and in part to the retreat and/or break off of subducted oceanic slabs of the paleo Pacific Plate. We consider that the sequential evolution and deep-seated processes of Late Mesozoic multi-plate convergence in East Asia not only created complex marginal and intracontinental orogenic tectonic systems, but also controlled the explosive magmatism and mineralization in east China, meanwhile it caused seesaw change of landform in east-west direction. High plateaus possibly generated in East Asia during the middle-Late Jurassic to early Cretaceous convergent orogenesis may have been collapsed during the late-stage extensional tectonism. Coeval with the break-up of the Pangean supercontinent, the East Asia convergence evolved stepwisely from East Asia to Eurasia, then on the way to a future supercontinent.
