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 debat...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.展开更多
The Beikang Basin is located in the southern part of the South China Sea(SCS),which is one of most tectonically complex sea areas.It is a deepwater sedimentary basin that was mainly deposited during the Cenozoic era.O...The Beikang Basin is located in the southern part of the South China Sea(SCS),which is one of most tectonically complex sea areas.It is a deepwater sedimentary basin that was mainly deposited during the Cenozoic era.Owing to data restrictions,the research on carbonate platforms of this area is still in its infancy.High-resolution seismic data are analyzed to identify the Miocene carbonate platforms and reconstruct the architecture and growth history.The carbonate platforms of Beikang Basin began to develop in the Late Oligocene-Early Miocene,were extended in the Middle Miocene,and declined in the Late Miocene.The carbonate platform mainly developed during two periods:the Oligocene to the Early Miocene,and the Middle Miocene.The carbonate platforms that developed in the Middle Miocene were the most prosperous.The Middle Miocene carbonate platform in the Beikang Basin can be divided into three stages.In the first stage,the platforms had wide range which were thin.During the second stage,the platforms had a smaller range that was controlled by faults.In the third stage,the platforms were gradually submerged.The platform structure developed in the Middle Miocene at the Beikang Basin was controlled by the rate of rising/falling of the sea level and the carbonate growth rate.Based on an analysis of these changes and relationship,the platform can be divided into several patterns:retrogradation,submerged,aggradation,progradation,outward with up-stepping,outward with down-stepping,and down-stepping platforms.At the top of the carbonate platforms in the Beikang Basin a set of carbonate wings or mushrooms usually appeared.These were formed during a period of relative sea-level decline.It is believed that the Miocene carbonate platforms in the Beikang Basin are mainly controlled by tectonic and sedimentary environments,and are also affected by terrestrial detritus.展开更多
基金Supported by the Youth Innovation Promotion Association CASthe National Key Research and Development Program of China(No.2021YFC3100604)+5 种基金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)。
文摘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.
基金supported by Geological Investigation Programs of China Geological Survey(Grant No.DD20190213 and No.DD20191009)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0208)the Open Fund of MLR Key Laboratory of Marine Mineral Resources(Grant No.KLMMR-2017-A-16)。
文摘The Beikang Basin is located in the southern part of the South China Sea(SCS),which is one of most tectonically complex sea areas.It is a deepwater sedimentary basin that was mainly deposited during the Cenozoic era.Owing to data restrictions,the research on carbonate platforms of this area is still in its infancy.High-resolution seismic data are analyzed to identify the Miocene carbonate platforms and reconstruct the architecture and growth history.The carbonate platforms of Beikang Basin began to develop in the Late Oligocene-Early Miocene,were extended in the Middle Miocene,and declined in the Late Miocene.The carbonate platform mainly developed during two periods:the Oligocene to the Early Miocene,and the Middle Miocene.The carbonate platforms that developed in the Middle Miocene were the most prosperous.The Middle Miocene carbonate platform in the Beikang Basin can be divided into three stages.In the first stage,the platforms had wide range which were thin.During the second stage,the platforms had a smaller range that was controlled by faults.In the third stage,the platforms were gradually submerged.The platform structure developed in the Middle Miocene at the Beikang Basin was controlled by the rate of rising/falling of the sea level and the carbonate growth rate.Based on an analysis of these changes and relationship,the platform can be divided into several patterns:retrogradation,submerged,aggradation,progradation,outward with up-stepping,outward with down-stepping,and down-stepping platforms.At the top of the carbonate platforms in the Beikang Basin a set of carbonate wings or mushrooms usually appeared.These were formed during a period of relative sea-level decline.It is believed that the Miocene carbonate platforms in the Beikang Basin are mainly controlled by tectonic and sedimentary environments,and are also affected by terrestrial detritus.
