End-Permian to mid-Triassic termination of the accretionary processes of the southern Altaids: implications for the geodynamic evolution, Phanerozoic continental growth, and metallogeny of Central Asia

Abstract

The Altaids is one of the largest accretionary orogenic collages in the world with the highest rate of Phanerozoic continental growth and significantmetallogenic importance. It is widely accepted that subduction-related orogenesis of the Altaids started in the late Precambrian and gradually migrated southward (present coordinates). How- ever, it is uncertain when and how the building of the Altaids was finally completed. Based on structural geology, geochemical, geochronological, and paleomagnetic data, this paper presents late Paleozoic to earlyMesozoic accretionary tectonics of two key areas, North Xinjiang in the west and Inner Mongolia in the east, together with neighboring Mongolia. The late Paleozoic tectonics of North Xinjiang and adjacent areas were characterized by continuous southward accretion along the wide southern active margin of Siberia and its final amalgamationwith the passivemargin of Tarim, which may have lasted to the end-Permian to early/ mid-Triassic.