Research on the extension of faults zones in northern margin of the South China Sea based on the gravity data

The South China Sea located in the intersection of Eurasian plate,Pacific plate and Indian-Australia plate,is always the research focus of geologists and geophysicists both at home and aborad because of its special structure location.The South China Sea has experienced complicated geological process after the Mesozoic,that Fault systems develop well in northern margin of the South China Sea such as Red River active fault zone which is northwest-direction,Binhai fault zone which is northeast-direction,the edge fault of Xisha trough which is south-north-direction and West Margin fault which is east-west-direction.In order to further study the areal geology structure and tectonic movement character in north margin of the South China Sea,the paper is mainly focused on the fractures distribution and their combination relations.In light with gravity data in norther marine of the South China Sea,Various informations on faults were obtained by target field extraction,first vertical direction derivative processing and normalized vertical derivative of the total horizontal derivative(NVDR_THDR).The characters of the principal faults of the study area were analysed based on geological and geophysical date, resulting in fault distribution map. The paper emphatically discusses the Red River Fault Zone,Binhai Fault Zone of South China Sea and Mesozoic subduction-accretion zone,would offer helps of extending of the faults in sea area.It holds that Red River Fault zone connects with East-Vietnam Fault and Zhongjian rise Fault, which should be the demarcation line of Indochina and South China blocks,however the Binhai Fault Zone should be the suture line of South China and South China Sea blocks.