南海海底地震仪三维深地震探测的进展及挑战  

Current Status and Challenges for Three-Dimensional Deep Seismic Survey in the South China Sea

作　　者：赵明辉[1] 杜峰 王强[1,2] 丘学林 韩冰[3] 孙龙涛 张洁[4] 夏少红[1] 范朝焰[1,2] Zhao Minghui;Du Feng;Wang Qiang;Qiu Xuelin;Han Bing;Sun Longtao;Zhang Jie;Xia Shaohong;Fan Chaoyan(Key Laboratory of Ocean and Marginal Sea Geology of Chinese Academy of Sciences,South China Sea Institute of Oceanology,Chinese Academy of Science;University of Chinese Academy of Science;Guangzhou Marine Geological Survey,China Geological Surve;The Second Institute of Oceanography,State Oceanic Administratio)

机构地区：[1]中国科学院边缘海与大洋地质重点实验室中国科学院南海海洋研究所,广东广州510301 [2]中国科学院大学,北京100049 [3]中国地质调查局广州海洋地质调查局,广东广州510075 [4]国家海洋局第二海洋研究所,浙江杭州310012

出　　处：《地球科学》2018年第10期3749-3761,共13页Earth Science

基　　金：国家自然科学基金项目(Nos.41730532,91428204,41576070,41376063);广东省基金团队项目(No.2017A030312002);国家自然科学基金委员会共享航次(No.NORC-08)

摘　　要：获取深部速度结构是认识南海形成演化模式的基础.海底地震仪(OBS)二维与三维深地震探测技术是获取深部速度结构最成功的方法之一.OBS三维探测结果揭示:西南次海盆横跨残留扩张脊两侧洋壳不对称增生的速度结构特征;东部次海盆具有4种不同洋壳类型的速度结构;珍贝-黄岩海山链是在海盆停止扩张后6～10 Ma岩浆活动形成的;东沙隆起区显示了张裂期后的岩浆活动及其上涌通道;南海东北部马尼拉俯冲带前缘是受到张裂期后岩浆活动影响的减薄陆壳.IODP367-368钻探区实施的OBS三维探测将以建立南海洋陆转换带(COT)张裂-破裂机制模型为科学目标.OBS三维探测方法在南海各向异性、岩浆活动、形成演化等方面将继续发挥着不可替代的作用.The deep velocity structures are the basis for building the formation and revolution of the South China Sea（ SCS）. Two-dimensional（ 2 D） and three-dimensional（ 3 D） OBS surveys are successful technique to acquire the deep seismic structures. The results from 3 D OBS surveys in the SCS have enhanced the knowledge for theoretical concepts. In the Southwest sub-basin,the asymmetrical velocity structures have been presented across the extinct spreading ridge（ ESR） due to the development of detachment faults. In the central part of the east sub-basin,four types of crust have been defined： thin oceanic crust（ 〈5 km）; typical oceanic crust（ 5-6 km）;thick oceanic crust hosting post-spreading volcanoes（ 〉 6 km） with significant intrusive roots; and thick oceanic crust with enhanced spreading features（ 〉 6 km） but without significant roots. The post-spreading volcanoes（ Zhenbei-Huangyan seamounts chain） were formed 6-10 Ma ago during a N-S tensional episode,several millions of years after seafloor spreading ceased in the SCS,and emplaced where the crust was the weakest,might have been influenced by the Hainan plume activity through a buoyancy-driven partial meltingmechanism. The study on Dongsha uplift highlights magmatic activities through upwelling channels after rifting ceasing. The velocity structure in the Manila subduction zone（ northeastern SCS） shows the nature of the crust and its relationship with the Manila subduction slab. A 3 D OBS survey will be carried out in 2018 in the area of the IODP Legs 367-368,aiming at building a model of lithospheric rifting and breakup mechanism in the continent-ocean-transition（ COT） zone of the SCS. The joint 2 D and 3 D survey method will play a major role in the understanding of the SCS geodynamics by integrating IODP drilling results with information on the deep structures.

关 键 词：海底地震仪 三维深地震探测 岩浆活动 洋陆转换带 残留扩张脊 地球物理 

分 类 号：P315[天文地球—地震学]