Characteristics of Cenozoic sedimentary formation and tectonic evolution of South China Sea

The Cenozoic sedimentary formation of South China Sea can be classified into three types, namely the stable, substable and unstable types, and two cycles, the Lower (E1-E2) and Upper (Q-E3) cycles by the unconformity of Late Mid-Eocene. In the North and South Continental Margins two sedimentation cycles developed but only the upper one developed in the Central Ocean Basin. By analyses of the sedimentary formation, it is suggested that Lower Cycle was fill sediment, and mainly fluvial-lacustrine facies; the Upper Cycle was onlap sediment, and was mainly shallow marine or deep ocean. It indicates that the Central Ocean Basin formed after Mid-Oligocene, and the nappe and obduction of Philippines Island-Arc and the counter-clockwise rotation of Kalimantan resulted in the gradual closing of Paleo-South China Sea.