Abstract:

Northern continental margin basins in South China Sea are located among Pacific Plate, Indian Plate and Philippine Sea Plate; these plates had different impacts on these basins. The study of the evolution of the three plates and paleoSouth China Sea showed that the stress environment had been changed in the late Cretaceous in northern continental margin area. The stress environment was compressional in the Lower Cretaceous and had been changed into extension in the Late Cretaceous. The cause of extensional environment was different since the Late Cretaceous. Extensional environment was caused by stress relaxation of eogenetic orogen in South China continental margin area, by southern subduction of paleoSouth China Sea and by rollback of the subducting Pacific slab from the late Cretaceous to the Paleocene, and the early rift basin began to form in continental margin in northern South China Sea. Continued reduction of western subduction rate of Pacific slab and southern subduction of PaleoSouth China Sea formed the same stress environment in the Eocene and rift basins formed continually. Southern movement of mantle materials and southern subduction of PaleoSouth China Sea formed the extensional environment from the Oligocene to the EarlyMiocene and seafloor spreading of South China Sea began in the Early Oligocene. The three plates affected these north continental margin basins in South China Sea together since the Middle Miocene.

Key words: tectonic dynamics, northern continental margin basins in South China Sea, Pacific Plate, Indian Plate, Philippine Sea Plate