Late Mesozoic multi-plate convergence in East Asia: Insights from 3-D global mantle flow models

Abstract

Due to the Mesozoic multi-plate convergence, prominent continental marginal tectonic belts were formed in East Asia. The significant intra-continental magmatic events in the interior of East Asia were also closely related to the subduction of the surrounding oceans. Therefore, clarifying the subduction-related mantle dynamics during the Mesozoic super-convergence in East Asia is critical in understanding the crust-mantle interactions and the episodic tectono-magmatism. In this study, we obtain the subduction-related dynamic topography by coupling global mantle flow and plate reconstruction motions to capture the evolution scenarios in 200–90 Ma. Our modeling results are as follows: (1) In the Early Jurassic, the East Asian continental margin breakup is closely related to the mantle-driven dynamic topography. The offshore dynamic subsidence dominates the continental breakup. (2) The closure of the Paleo-Tethys Ocean and the subduction of the Bangonghu-Nujiang Ocean contribute to the southward migration of the dynamic topography. Concurrently, the continuous subduction of the Paleo-Pacific Plate leads to the onshore dynamic uplift, which results in subduction-related orogenesis in eastern East Asia. The dynamic uplift does not massively progress westward in Mainland China, suggesting that extensive intra-continental compressional deformation results from tectonic uplift rather than mantle-induced dynamic uplift. (3) The regression of the dynamic subsidence zone since 130 Ma marks the start of the topographic collapse in the East Asian continental margin through the back-arc extension. (4) The alternating compression-extension scenarios are identified in the main compressional and extensional stages, respectively, showing that dynamic topography is closely related to the evolution of the marginal tectonic belts in eastern East Asia. In conclusion, the subduction-related dynamic topography systematically reveals the deep dynamics involved in the formation, evolution, and collapse of the marginal tectonic belts in East Asia and is of great significance in understanding the related mantle dynamics during the Late Mesozoic.