Intracontinental deformation in a frontier of super-convergence: a perspective on the tectonic milieu of the South China Block

Abstract

Since Mesozoic, the South China region has been located at the center of a triangular area surrounded by westward subduction of the Pacific plate, northward subduction of the India Plate beneath the Eurasia Plate, and collision of the North and South China blocks along the Central China Orogen. This region thus marks the frontier of a super-convergent regime. Within the super-convergence domain, the compressional structures in the center of the South China Block are mainly characterized by shortening, thrusting and decollement. The block underwent inhomogeneous rejuvenation of the pre-existing crust and lithospheric structures through reactivation of late-stage activities. The surface deformation of the Xuefeng Intracontinental Tectonic System within the South China Block is possibly derived from intraplate tectonics. Particularly, the distinct magmatism between the west and east limbs of the Xuefeng Precambrian Uplift is a possible response of the rheological structure of the lithosphere. The deep structures as revealed from tomographic studies show marked difference of lithosphere architecture between the eastern and western sub-blocks of the South China Block. These data illustrate the long-term mosaic of multi-block convergence which led to present-day inhomogeneity in the continental lithosphere in South China. A comparison of the intensive contraction of the South China Block with the distinct features of rifting of the North China Block, brings out the contrasting structural and tectonic signatures developed in the same frontier of one of the largest super-convergent systems on the globe during the Mesozoic to Cenozoic. © 2011.