Researches on Geophysical Field Characteristics and Basement Fault System of South China Sea

Geophysical features and basement faults system of South China Sea are studied. According to characteristics of geophysical fields, South China Sea can be divided to four blocks, which are north margin block, Zhongsha-Xisha block, Nansha block and central basin block with different features. Inversion shows Moho discontinuity depth increase from land to sea and the distribution of continental crust, extensional crust, transitional crust and oceanic crust. The high frequency part of Dongsha high-value magnetic anomaly may be related with Cenozoic basalt and Mesozoic magmatic rocks, and the low frequency part developing high-velocity lower crust. Fault systems develop well in South China Sea and can be divided to four groups, which are northeast-direction fault group, eastwest-direction fault group, northwest-direction fault group and northsouth-direction fault group. On north margin and south margin of South China Sea, northeast-direction extension faults and northwest extension/extension-shear faults characterize the main tectonic framework of separated stripes in north-west direction and blocks in west-east direction.