Differential tectonic evolution and formation mechanism of three subsags in Wenchang Sag of Pearl River Mouth Basin,South China Sea  

作　　者：Qiu-Gen Zheng Jun-Liang Li Bao-Hua Lei Peng Song Qi Li De-Feng Shi Hao Liu Chang-Song Lin 

机构地区：[1]School of Ocean Sciences,China University of Geosciences(Beijing),Beijing,100083,China [2]Hainan Branch of the China National Ofshore Oil Corporation,Haikou,Hainan,570311,China [3]Qingdao Institute of Marine Geology,Qingdao,Shandong,266237,China [4]Laboratory for Marine Mineral Resources,Pilot National Laboratory for Marine Scence and Technoogy(Qingdao),Qingdao,Shandong,26637,China

出　　处：《Petroleum Science》2023年第3期1379-1394,共16页石油科学（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.91328201;42006068);Shandong Special Fund of Qingdao National Laboratory of Marine Science and Technology(No.2021QNLM020001-1).

摘　　要：Notable differences in the structural characteristics and evolution of three adjacent sub-sags,i.e.,the Wenchang sub-sags A,B,and C,on the downthrown side of the Zhu IlI South Fault in the Wenchang Sag,are significant as they affect the formation and distribution of the oil and gas in these three sub-sags.However,the differences in their tectonic evolutions and formation mechanisms have not yet been adequately explained.In this paper,stress analysis,equilibrium profiles,and paleogeomorphic restora-tion,are used to investigate the dynamic settings,formation mechanisms,and influencing factors of the structural deformation related to the formation of the Wenchang Sag based on interpretation of seismic data.The results of the stress analysis suggest clockwise deflection of the regional tensile stress direction from a WNW-ESE trend during the Early Paleocene to NW-SE and NNW-SSE trends during the Eocene,to a nearly N-S trend during the Oligocene,and finally to a NNE-SSW trend during the Miocene.This clockwise rotation of the regional tensile stress direction led to the formation of a dextral strike-slip stress component parallel to the NE-trending Zhu I South Fault.This strike-slip stress component formed a releasing bend in sub-sag A,and may be associated with the continuous subsidence of a thick sedimentary layer in sub-sag A.It also created a restraining bend in sub-sag B,which underwent multiple structural inversions during its extension and subsidence and has a relatively s mall sedimentary thick-ness.The double restraining bend in sub-sag C is considered to have been strongly uplifted and eroded in response to this strike-slip stress component.Four obvious structural inversions in sub-sag B are iden-tified in this paper.These structural inversions correspond to the last four regional tectonic movements.This interpretation suggests that the formation of the structural inversions was likely related to the strong tensile stress and the small intersection angle between the direction of the regional tensile stress an

关 键 词：Strike-slip stress Releasing bend Restraining bend Double restraining bend Structura linversion ZhuⅢSouthfault Wenchang sag Northern South China Sea 

分 类 号：P618.13[天文地球—矿床学]