Dynamics of the continental margins of South China Sea: scientific experiments and research progresses

作者：Li Jia Biao^*

来源：Chinese Journal of Geophysics, 2011, 54(12): 2993-3003.

DOI：10.3969/j.issn.0001-5733.2011.12.002

• Comprehensive geophysical survey
• Spreading propagation
• Depth-dependent stretching
• Magma-poor rifting
• Hydrocarbon potential

Comprehensive geophysical survey, including the multi-channel seismic survey with long streamer and large air-gun source and the wide-angle refraction/reflection seismic survey of OBS, has been deployed in the southern margin and Southwest Sub-basin of the South China Sea for the first time. Based on the interpretation of these geophysical data, combined with studies on tectonic structure, geochemistry, and dynamic simulation, etc, our project worked out the dynamics of the continental margin in South China Sea. Major conclusions are as follows: Two sea-floor spreading events occurred in Cenozoic. The first episode happened between 33. 5 similar to 25 Ma, and after a 1. 5 Ma tectonic adjustment, started the second episode of sea-floor spreading between 23. 5 similar to 15. 5 Ma. In both episodes the South China Sea experienced propagation rifting and spreading from east to west, resulting in a structural framework featured with blocks in north-south direction and segments in east-west direction; Cenozoic marginal basins in the northern and southern continental margins show different rift-terminated time, which correspond with the two episodic sea-floor spreading respectively. The continental crust of the South China Sea might have experienced depth-dependent stretching. The lower crust and top of upper mantle have been magnetized and no obvious velocity anomalies of the mantle have been found in oceanic basin. South China Sea margins are a kind of magma-poor rifting, although lower crustal bodies of high-velocity occur in the east of the northern margin, but without SDR. The origin and evolution of sediment basins on northern and southern continental margins are very distinct, and the hydrocarbon accumulations are distributed in a cirque with oil outside and gas inside. We believe that the hydrocarbon-bearing perspectives in southern continental marginal basins are superior to these northern continental marginal basins. In Mesozoic the northern and southern margin of the South China Sea were parts of the South China Continental Block, which was controlled by the Tethays and Pacific tectonic domains.

• 出版日期2011-12
• 单位国家海洋局第二海洋研究所