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引用本文:徐子英,汪俊,高红芳,姚永坚,朱荣伟,唐江浪,聂鑫,孙美静. 中沙地块南部断裂发育特征及其成因机制[J]. 中国地质, 2020, 47(5): 1438-1446.
XU Ziying,WANG Jun,GAO Hongfang,YAO Yongjian,ZHU Rongwei,TANG Jianglang,NIE Xin,SUN Meijing. The characteristics and formation mechanism of the faults in the southern part of the Zhongsha Bank[J]. Geology in China, 2020, 47(5): 1438-1446(in Chinese with English abstract).
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中沙地块南部断裂发育特征及其成因机制
徐子英1,2, 汪俊1,2, 高红芳1,2, 姚永坚1,2, 朱荣伟1,2, 唐江浪1, 聂鑫1, 孙美静1
1.自然资源部海底矿产资源重点实验室, 广州海洋地质调查局, 广东 广州 510075;2.南方海洋科学与工程广东省实验室 (广州), 广东 广州 511458
摘要:
利用最新多道地震剖面资料,结合重力、磁力、地形等地球物理资料,揭示了中沙地块南部断裂空间展布特征、断裂发育时期、断裂内部构造形变特征及深部地壳结构,并基于认识探讨了断裂的发育机制。研究结果认为,中沙地块南部陆缘构造属性为非火山型被动大陆边缘:地壳性质从西北向东南由减薄陆壳向洋陆过渡壳再向正常洋壳发育变化;Moho面埋深从中沙地块下方的26 km快速抬升到海盆的10~12 km;从中沙地块陡坡至其前缘海域的重力异常明显负异常区为洋陆过渡带,在重力由高值负异常上升到海盆的低值正、负异常的边界为洋陆边界。中沙地块南部发育有4组阶梯状向海倾的深大正断裂,主要发育时期为晚渐新世到中中新世。断裂早期发育与南海东部次海盆近NS向扩张有关,后期遭受挤压变形、与菲律宾海板块向南海的NWW向仰冲有关。该研究有助于更好认识南海海盆的扩张历史和南海被动大陆边缘的类型。
关键词:  断裂特征|发育机制|深部结构|海洋地质调查工程|中沙地块|南海海盆
DOI:10.12029/gc20200510
分类号:P542.3;P736.1
基金项目:国家自然科学基金项目(41606080,41576068)、广东省自然科学基金项目(2017A030312002)、中国地质调查局国家海洋专项项目(GZH201400202,DD20160138,DD20190378,1212011220117,1212011220116,DD20190366,DD20190577,DD20190209,DD20190216,GZH201400203)及南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(GML2019ZD0208)联合资助。
The characteristics and formation mechanism of the faults in the southern part of the Zhongsha Bank
XU Ziying1,2, WANG Jun1,2, GAO Hongfang1,2, YAO Yongjian1,2, ZHU Rongwei1,2, TANG Jianglang1, NIE Xin1, SUN Meijing1
1.Key Laboratory of Marine Mineral Resources, Ministry of Natural Resources, Guangzhou Marine Geological Survey, Guangzhou 510075, Guangdong, China;2.Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou), Guangzhou 511458, Guangdong, China
Abstract:
On the basis of the latest multi-channel seismic profiles and geophysical data such as gravity, magnetism and topography, the spatial distribution characteristics of faults, the development period of faults, the internal structural deformation feature of faults and deep crustal structure in the southern Zhongsha Bank (ZB) were revealed, and the formation mechanism of the faults was also discussed. The results show that the tectonic property of the southern continental margin of ZB is non-volcanic passive continental margin. From northwest to southeast, the crustal properties change from thinned continental crust to oceanic-continental transitional crust and then to normal oceanic crust. The depth of Moho discontinuity rises rapidly from 26 km beneath the ZB to 10-12 km beneath the ocean basin. The obvious negative gravity anomaly area from the steep slope of the ZB to the coast front is the oceaniccontinental transitional zone, and the boundary of gravity anomaly change from high value negative anomaly to low value positive and negative anomaly in the ocean basin is the oceanic-continental boundary. There are four sets of deep and large normal faults with stepped sea-dipping in the southern part of the ZB, which were mainly developed in the Late Oligocene to the Middle Miocene. The early extension of the fault development mechanism was related to the NS-trending extension of the sub-basin in the eastern South China Sea (SCS), and the later compressive stress was related to the NW-trending subduction of the Philippine plate towards the SCS. This study is helpful to the better understanding of the expansion history of the South China Sea basin and the types of passive continental margins in the SCS.
Key words:  fault characteristics|formation mechanism|deep structure|marine geological survey engineering|Zhongsha Bank|South China Sea basin