Late Mesozoic intracontinental deformation and magmatism in North and NE China in response to multi-plate convergence in NE Asia: An overview and new view

Abstract

We review in this paper the major late Mesozoic contractional deformation in North and NE China and establish the tempo-spatial distribution pattern of Jurassic-Cretaceous magmatism, with the aim at clarifying its link with evolving multi-plate convergent geodynamics in NE Asia. We recognize two major changes in tectonic regime, one occurring at ~170 Ma, which marks the tectonic switch from extensional to compressional regimes, while another at ~135 Ma which manifests the change from compressional to extensional settings. Accordingly, Jurassic-Cretaceous magmatism migrated from the marginal zones in ~200 -170 Ma to the continental interior in 170-135 Ma and then was followed by Mid-Cretaceous (135-120 Ma) magmatic flare-up in the continental interior, which migrated progressively eastward since ~120 Ma. Based on these observations, we make a division of three tectonic stages and discuss their plate geodynamic setting. (1) The early stage in 200-170 Ma was dominantly under extensional setting with A-type granitoids and bi-modal volcanism occurring along the eastern and northern marginal zones. (2) The middle stage in 170-135 Ma was manifested by significant multi-directional crustal shortening and rejuvenation of the ancient orogenic belts, as distant response to multi-plate convergence along the East Asia continental margins. (3) The late stage was manifested first by a thermal surge in 135-120 Ma with the formation of extensional structures and rift basins in the continental interior, then followed by alternation of tectonic compression and extension, related to the effect of paleo-Pacific slab subduction. We propose that the thickening acquired during the middle tectonic stage and subsequent lithospheric thinning in the late stage triggered large-scale crustal melting, episodic magmatism and associated metallogenic outbreak in North and NE China.