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| Mesozoic subduction-accretion zone in northeastern South China Sea inferred from geophysical interpretations | |
| 基金项目： | 中国科学院资助项目;中国科学院资助项目 |
| 摘 要： | The northern South China Sea (SCS) is an impor- tant offshore exploration area of China, producing over 10 million tons of oil from Cenozoic reservoirs annually since 1996. The increasing energy consump- tion in China demands a rapid expansion of hydrocar- bon exploration to new types, including pre-Cenozoic sources and reservoirs. This has stimulated a new phase of pre-Cenozoic researches in the area. So far more than 100 exploration wells have reached the pre-Cenozoic basement in northe… |
| 收稿时间： | 18 March 2005 |
| 修稿时间： | 25 October 2005 |
Mesozoic subduction-accretion zone in northeastern south china sea inferred from geophysical interpretations |
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| Authors: | ZHOU Di WANG Wanyin WANG Jialin PANG Xiong CAI Dongsheng SUN Zhen |
| Institution: | 1. Key Laboratory of Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China 2. College of Geological and Topographical Engineering, Chang'an University, Xi'an 710054, China 3. Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China 4. China National Offshore Oil Co. Limited - Shenzhen Branch, Shenzhen 518067, China 5. China National Offshore Oil Co. Limited - Research Center, Beijing 100027, China |
| Abstract: | A segment of Mesozoic subduction-accretion zone was inferred across the northeastern South China Sea at approximately NE45° orientation. Basic evidence includes the following: A belt of peek gross horizontal Bouguer gravity gradient (PGHGBA) is comparable in size and intensity to that of the Manila subduction-accretion zone. A belt of high positive magnetic anomalies appears to the north and sub-parallel to the PGHGBA, representing the volcanic arc associated to the subduction zone. The PGHGBA crosses obliquely both Cenozoic structures and present seafloor topography, indicating a pre-Cenozoic age. The segment is offset left-laterally by NW-running strike-slip faults, in concord with the Mesozoic stress field of South China. In addition, the existence of the subduction zone is supported by wide-angle seismic data obtained in different years by different institutions. At approximate localities, a north-dipping ramp of Moho surface is indicated by records of ocean-bottom seismometers, and a strong reflector about 8 km beneath the Moho reflector is indicated by both OBS and long-cable seismic records. The identification of a segment of Mesozoic subduction zone in NE South China Sea fills nicely the gap of the Great Late Mesozoic Circum SE Asia Subduction-acrretion Zone, which extended from Sumatra, Java, SE Kalimantan to N Palawan, and from Taiwan, Ryukyu to SW Japan. |
| Keywords: | Mesozoic subduction zone SE Asia NE South China Sea geophysics |
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