RESEARCH PROGRESS IN CONTINENTAL MARGIN DYNAMICS OF SOUTH CHINA SEA: FROM CONTINENTAL RIFTING TO SEA-FLOOR SPREADING

The South China Sea, as one of the largest marginal seas along the western Pacific, is located in the juncture of the Pacific, Eurasian and Indian-Australian plates. It is a right place for studying rift processes from the extension of the continental lithosphere up to the formation of the oceanic crust. We discussed in this paper the dynamics of the continental margin of the South China Sea and new progresses were summarized. Detailed data suggest that the northern continental margin of the South China Sea is a magma-poor passive margin. Magma underplating discovered in the east part was caused by the magmatism after the cessation of the sea-floor spreading. No high-velocity layer has been discovered under the southern continental margin, which indicates a magma-poor margin similar to the north. The stretching factors are different between the upper and lower crust of the continental margin, showing that the stretching is depth-dependent and not uniform vertically. Two sea-floor spreading events were observed in the Cenozoic. Spreading propagated from northeast to southwest and shows a transition from a steady sea-floor spreading in the east to an initially unsteady one with partly continental rifting in the west. Arguments remain about the opening mechanism of the South China Sea. Comprehensive study is required for future research.