Tectono-thermal Evolution Modeling Of The South China Sea Continental Margin Basins

As an important marginal sea in the Western Pacific, the South China Sea (SCS)is about 3.5 million km2, experienced complex history with the three large plates'interaction among the Eurasian Plate, the Pacific plate and the Australia-India plate.The South China Sea has been considered as one natural laboratory on continentalmargin tectonics and dynamics research, which experienced the large-scaleconvergence, collision, strike-slip and the close of Tethys during the Mesozoic period,and continental margin lithosphere breakup, the central and southwestern subbasinseafloor spreading, the Pacific Plate and the Indo - Australian plate subduction andcollision during the Cenozoic period.In this paper, based on the TSM basin modeling thoughts proposed byacademician Zhu, and"Three Sea Strategy"proposed by academician Liu, supportedby the National Basic Research Development Program of the South China Seacontinental margin dynamics and oil & gas resource potential, SINOPECforward-looking research project, and CNOOC national oil & gas special project, wefinished seismic interpretation and modeling of the southwestern subbasin of SouthChina Sea, tectonic and thermal modeling of main sedimentary basins on the southernand northern continental margin of South China Sea.Line NH973-1 interpretation shows that the different oceanic crust basement ofsouthwestern subbasin of South China Sea suggests the different spreading rate,magmatism and deformation under different seafloor spreading rate. Huge thickenedsedimentary body at the tip of the southern lower slope may be formed in theCenozoic era and affected by later gravity slump.The rifted sedimentary basins on the northern SCS show different subsidence andheating process, which is controlled by tectonic movement, fault and later periodmagmatic activity. The second heating period in the Qiongdongnan Basin correspondsto NanHai movement and the onset of seafloor spreading, but the end time delayed atthe southeastern part of the Qiongdongnan Basin and the Pearl River Mouth Basin.Late Pliocene thermal event at Qiongdongnan Basin resulted from a very strong rapidsubsidence, the heating effect weakened from west to east, and disappeared in thePearl River Mouth Basin.It is different for the thermal history of the southern continental margin of SCS.Southern continental margin shows gradual cooling from SW to NE, and the basementheat flow in the deepwater region is higher than that in the shallow water regionobviously. Later period thermal evolution on the southern continental margin wascontrolled by convergence, collision, and strike-slip activity in the area, but at thesame period the northern continental margin experienced different activity.