West Pacific-type convergent boundaries: Role in the crust growth history of the Central-Asian orogen

Abstract

Convergent plate boundaries like that between the present western Pacific and eastern Asia constitute a special type related to subduction in provinces of mantle superplumes. The West Pacific-type convergent boundaries may reach thousands of kilometers across and consist of several structures that regularly grade one to another from ocean to continent: island arcs, marginal and back-arc basins, and continent-margin rifts with OIB volcanism.Convergent boundaries of the West Pacific type contributed to Phanerozoic crust growth in Central Asia as accretionary structures of the Central Asian orogen on the southern periphery of Siberia belonged to such a convergence zone. The lithosphere of Siberia interacted with hot mantle as the continent moved over the African superplume, or over the respective large low shear velocity province (LLSVP), from the Vendian to the Early Mesozoic. In the Late Cenozoic, Siberia left the African LLSV province and shifted to the Pacific LLSVP. The influence of the latter has controlled the structure and evolution of the convergent boundary in the western Pacific, namely, widespread within-plate magmatism in continental Asia in Late Mesozoic and Cenozoic time.