南沙海区万安盆地构造演化与成因机制  

Tectonic evolution and genetic mechanism of the Wan'an Basin,southern South China Sea

作　　者：姚永坚[1] 吕彩丽 王利杰 徐行[1] 杨楚鹏[1] 伊善堂 Yao Yongjian;Lu Caili;Wang Lijie;Xu Xing;Yang Chupeng;Yi Shantang(Guangzhou Marine Geological Survey, Guangzhou 510760, China;CNOOC Research Institute, Beijing 100028, China;CAS Key Laboratory of Oceanology and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Ouangzhou 510301 , China;University of Chinese Academy of Sciences, Beij ing 100049, China)

机构地区：[1]广州海洋地质调查局,广东广州510760 [2]中海油研究总院,北京100028 [3]中国科学院南海海洋研究所边缘海与大洋地质重点实验室,广东广州510301 [4]中国科学院大学,北京100049

出　　处：《海洋学报》2018年第5期62-74,共13页

基　　金：国家自然科学基金项目(41576068;91428205;91128203);中国地质调查局项目(DD20160227;1212011220116;GZH201400203;DD20160138;DD20160140)

摘　　要：本文基于地震、钻井和区域地质资料,运用回剥法和平衡剖面技术定量研究了万安盆地的构造沉降和伸展程度,重建盆地的构造演化史并探讨其成因机制。模拟结果表明,万安盆地构造沉降曲线为多段式,其南北部构造沉降差异明显,且沉降中心逐渐向南发展的趋势。晚始新世-渐新世(37.8~23.03Ma BP)盆地中、北部快速沉降,存在两个沉降中心;早中新世(23.03~16.0Ma BP)盆地南部也发生快速沉降,整个盆地存在3个沉降中心;中中新世(约16.0~11.63Ma BP)沉降作用减弱,盆地进入裂后热沉降期。万安盆地的伸展和形成演化呈现北早南晚的特征,与南海海底扩张密切相关,同时受控于万安断裂带交替地右旋-左旋走滑作用,是伸展和走滑双重作用的结果。盆地的构造演化过程可细分为4个阶段:初始裂谷期、主要裂谷期、走滑改造期和裂后加速沉降期。Based on available seismic,well and regional geology data,tectonic subsidence and extension degree of the Wan＇an Basin were calculated by balanced cross-section and backstripping techniques to reconstruct tectonic evolution history of the basin and further probe into its genetic mechanism.The results indicate that tectonic subsidence curves are composed of multiple-line sections and there exists differential subsidence in the northern and southern basin,and the subsidence center of the whole gradually shifts southward.Two subsidence centers developed in Late Eocene to Oligocene（37.8—23.0 Ma BP）and tectonic subsidence mainly concentrated in the middle and northern basin,while the southern part of the basin subsided rapidly in Early Miocene（23.03—16.0 Ma BP）and there exists three subsidence centers.However,tectonic subsidence has decreased since the Middle Miocene（-16.0-11.63 Ma BP）and the whole basin has entered into post-rift thermal subsidence stage.Basin extension is closely related to the seafloor spread of South China Sea and the stretching in the middle-northern basin is earlier than the southern basin.It is inferred that alternating sinistral to dextral strike-slip motions along the Wan＇an Fault Zone control on the formation and evolution of Wan＇an Basin,as a result of rifting and strike-slipping.The basin tectonic evolution is divided into four stages：initial rift,syn-rift,strike-slip reformation,and post-rift accelerated thermal subsidence stages.

关 键 词：伸展 构造演化 万安盆地 南海 

分 类 号：P736.1[天文地球—海洋地质]