先存俯冲陆缘背景下南海北部陆缘断陷特征及成因  

Characteristics and origin of continental marginal fault depressions under the background of preexisting subduction continental margin, northern South China Sea, China

作　　者：庞雄 郑金云 梅廉夫[3] 柳保军 张忠涛 吴哲 冯轩 PANG Xiong;ZHENG Jinyun;MEI Lianfu;LIU Baojun;ZHANG Zhongtao;WU Zhe;Feng Xuan(CNOOC Ltd.-Shenzhen,Shenzhen 518054,China;CNOOC Ltd.-Deepwater,Shenzhen 518054,China;Faculty of Marine Science and Technology,China University of Geosciences,Wuhan 430074,China)

机构地区：[1]中海石油(中国)有限公司深圳分公司,广东深圳518054 [2]中海石油深海开发有限公司,广东深圳518054 [3]中国地质大学(武汉)构造与油气资源教育部重点实验室,武汉430074

出　　处：《石油勘探与开发》2021年第5期1069-1080,共12页Petroleum Exploration and Development

基　　金：国家科技重大专项“大型油气田及煤层气开发”(2016ZX05026-003,2011ZX05025-003);中海石油有限公司科技项目(YXKY-2012-SHENHAI-01);中海石油(中国)有限公司“十三五”科技重点项目(CNOOC-KJ 135 ZDXM 37 SZ 01 SHENHAI)。

摘　　要：基于地震和钻井新资料,并综合近期相关研究成果,系统分析南海北部陆缘珠江口盆地地壳岩石圈构造和盆地结构的多样性及其复杂的发育演化过程。研究认为,珠江口盆地存在壳幔拆离、壳间拆离和上地壳内拆离3种不同构造层次的拆离断裂,不同类型的伸展拆离控制不同的盆地结构构造;位于近端带的珠一坳陷发现多个受上地壳内拆离断层控制的断陷,这些拆离断裂通常受到岩浆侵位的改造或先存断裂控制;位于超伸展区的白云凹陷—荔湾凹陷的内部结构特征差异明显,白云主洼的岩浆作用较弱,受控于壳幔拆离系,发育为宽深断陷;白云凹陷东部和西南断阶带在中始新世之后岩浆活动广泛,地壳韧性伸展变形,发育受上地壳内拆离断裂控制的宽浅断陷。对比经典的大西洋边缘岩石圈伸展破裂方式和盆地构造演化,认为中生代俯冲陆缘背景的先存构造和新生代岩浆活动是南海北部陆缘断陷结构多样化的重要控制因素。图10参28。Based on the new seismic and drilling data and the recent related research results, this paper systematically analyzes the diversity and complexity of evolution process of crustal lithosphere structure and basin structure in the Pearl River Mouth Basin on the northern margin of the South China Sea. Three types of detachment faults of different structural levels exist: crust-mantle detachment, inter-crust detachment and upper crust detachment. It is considered that different types of extensional detachment control different subbasin structures. Many fault depressions controlled by upper crust detachment faults have been found in the Zhu I Depression located in the proximal zone. These detachment faults are usually reformed by magma emplacement or controlled by preexisting faults. Baiyun-Liwan Sag located in the hyperextension area shows different characteristics of internal structure. The Baiyun main sag with relative weak magmatism transformation is a wide-deep fault depression, which is controlled by crust-mantle detachment system. Extensive magmatism occurred in the eastern and southwest fault steps of the Baiyun Sag after Middle Eocene, and the crust ductile extensional deformation resulted in wide-shallow fault depression controlled by the upper crust detachment fault. Based on the classical lithosphere extensional breaking and basin tectonic evolution in the Atlantic margin, it is believed that the magmatic activities and pre-existing structures in the Mesozoic subduction continental margin background are important controlling factors for the diversified continental margin faulted structures in the northern South China Sea.

关 键 词：南海北部陆缘 先存构造 岩浆作用 多层次拆离断裂 断陷结构 珠江口盆地 

分 类 号：TE122[石油与天然气工程—油气勘探]