Formation of the Zengmu and Beikang Basins,and West Baram Line in the southwestern South China Sea margin

查看全文 作　　者：Bing [1,2,3,4,5]HAN;Zhongxian [1,3]ZHAO;Xiaofang [1,3]WANG;Zhen [1,3]SUN;Fucheng [1,3]LI;Benduo [2,4]ZHU;Yongjian [2,4]YAO;Liqiang [2,4]LIU;Tianyue [2,4]PENG;Genyuan [6]LONG 机构地区：[1]Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 511458,China;[2]Key Laboratory of Marine Mineral Resources,Ministry of Natural Resources,Guangzhou 511458,China;[3]Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;[4]Guangzhou Marine Geological Survey,China Geological Survey,Ministry of Natural Resources,Guangzhou 511458,China;[5]University of Chinese Academy of Sciences,Beijing 100049,China;[6]Hainan Key Laboratory of Marine Geological Resources and Environment,Haikou 570206,China 出　　处：《Journal of Oceanology and Limnology》索引2023年第41卷第2期,共20页 基　　金：Supported by the Youth Innovation Promotion Association CAS;the National Key Research and Development Program of China(No.2021YFC3100604);the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0205);the Guangzhou Municipal Science and Technology Program(No.201904010285);the K.C.Wong Education Foundation(No.GJTD-2018-13);the Hainan Key Laboratory of Marine Geological Resources and Environment(No.HNHYDZZYHJKF003);the China Geological Survey(No.DD20190378);the National Natural Science Foundation of China(No.42076077)。 摘　　要：The Zengmu and Beikang basins,separated by the West Baram Line(WBL)in the southwestern South China Sea margin,display distinct geological and geophysical features.However,the nature of the basins and the WBL are debated.Here we explore this issue by conducting the stratigraphic and structural interpretation,faults and subsidence analysis,and lithospheric finite extension modelling using seismic data.Results show that the WBL is a trans-extensional fault zone comprising normal faults and flower structures mainly active in the Late Eocene to Early Miocene.The Zengmu Basin,to the southwest of the WBL,shows an overall synformal geometry,thick folded strata in the Late Eocene to Late Miocene(40.4-5.2 Ma),and pretty small normal faults at the basin edge,which imply that the Zengmu Basin is a foreland basin under the Luconia and Borneo collision in the Sarawak since the Eocene.Furthermore,the basin exhibits two stages of subsidence(fast in 40.4-30 Ma and slow in 30-0 Ma);but the amount of observed subsidence and heat flow are both greater than that predicted by crustal thinning.The Beikang Basin,to the NE of the WBL,consists of the syn-rift faulted sub-basins(45-16.4 Ma)and the post-rift less deformed sequences(16.4-0 Ma).The heat flow(~60 mW/m2)is also consistent with that predicted based on crustal thinning,inferring that it is a rifted basin.However,the basin shows three stages of subsidence(fast in 45-30 Ma,uplift in 30-16.4 Ma,and fast in 16.4-0 Ma).In the uplift stage,the strata were partly folded in the Late Oligocene and partly eroded in the Early Miocene,which is probably caused by the flexural bulging in response to the paleo-South China Sea subduction and the subsequent Dangerous Grounds and Borneo collision in the Sabah to the east of the WBL. 关 键 词：tectonic subsidence foreland basin West Baram Line Zengmu Basin Beikang Basin South China Sea