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Cenozoic Tectono-Sedimentary Evolution in the Middle Part of Northern Continental Shelf-Slope Region, South China Sea

DING Wei-wei1, LI Ming-bi1, HE Ming2, TANG Yong1, FANG Yin-xia1   

  1. 1. Key Laboratory of the Submarine Geoscience, State Oceanic Administration, Hangzhou 310012, China;2. CNOOC China Limited-Shenzhen, Guangzhou 510240, China
  • Received:2009-09-20 Revised:2009-09-20 Online:2009-09-20 Published:2009-09-20

Abstract: The middle part of the northern continental shelf-slope region lies in the south of the Pearl River Basin. As an important structure unit of the northern continental margin of the South China Sea, it has experienced multiphase tectonic events and bears a thinned crust, upon which Cenozoic rifted-depressions with great hydrocarbon potential are developed. Several seismic profiles crossing the study area are introduced in this article. Based on the interpretations and balanced cross-section restorations of these profiles, combined with structural geology, a Cenozoic tectono-sedimentary model is established. The results show that three stages can be proposed for this region: the rift stage from Paleocene to Eocene, the rift-depression stage from Oligocene to the e Middle Miocene. The sedimentation environment transformed from the fluvial and lake facies to the shallow sea facies, and finally to the deep sea facies. The existence of NW-SE direction mantle flow under the continental crust in the north continental margin of South China Sea made the extension activities migrate from north to south. Results also show that the depressions (such as the Baiyun Sag) on the continental slope are featured by ductile deformation.It appears to be caused by the ductile thinning and necking of the crust in response to hot lithopheric stretching, together with mantle upwelling.