The acquisition of seabed physical parameters is one of the focuses of marine acoustic researches.However,the activesource ocean bottom seismometer(OBS)detection method in the marine geophysical research is rarely use...The acquisition of seabed physical parameters is one of the focuses of marine acoustic researches.However,the activesource ocean bottom seismometer(OBS)detection method in the marine geophysical research is rarely used to acquire seabed physical parameters,and less work is performed in the Arctic.In this study,two active-source OBS data collected from the 9th and 11th Chinese National Arctic Research Expedition(CHINARE)are selected to obtain the physical parameters of seabed sediments.Two kinds of energy spark are used as the active sources,while the cost function inversion method is used based on the arrival time difference between the reflected and direct waves.The thickness and sound velocity of the sediment layers are obtained by inversion,and the empirical formula is used to calculate the physical parameters of the seabed sediment,which are compared with the measured results.The cost function inversion method based on the time difference of arrival of the reflected and direct waves is tested to be effective and feasible in the inversion of seabed parameters from active-source OBS data.The method is further applied to obtain the physical parameters of Chukchi seabed sediments,which provides the idea and reference for the application of marine geophysical activesource OBS detection technology in the inversion of polar seabed physical parameters.展开更多
The Lishui Sag, in the East China Sea Shelf Basin, is rich in hydrocarbons, with the major hydrocarbon-bearing layers being the Paleocene Mingyuefeng clastic rocks. Analysis of the implicit geologic background informa...The Lishui Sag, in the East China Sea Shelf Basin, is rich in hydrocarbons, with the major hydrocarbon-bearing layers being the Paleocene Mingyuefeng clastic rocks. Analysis of the implicit geologic background information of these Paleocene clastic rocks using petrological and geochemical methods has significant practical importance. These Paleocene sandstones are mainly lithic arenite, lithic arkose and greywacke, composed of K-feldspar, plagioclase, authigenic clays, silica and carbonates. As continental deposits, Yueguifeng clastic rocks have high aluminosilicate and mafic detritus contents, while the Lingfeng and Mingyuefeng Formations are rich in silica due to an oscillating coastal marine depositional environment. The major element contents of these Paleocene sandstones are low and have a concentrated distribution, indicating that the geochemical composition is non-epigenetic, transformed by sedimentary processes and diagenesis. The Yueguifeng detritus comprises recycled sediments, controlled by moderate weathering and erosion, while the Lingfeng and Mingyuefeng detritus is interpreted as primarily first-cycle materials due to low chemical weathering. In the Late Cretaceous to Early Paleocene, the Pacific Plate began subducting under the Eurasian Plate, causing an orogeny by plate collision and magma eruption due to the melting of subducted oceanic crust. This resulted in the dual tectonic settings of "active margin" and "continental island arc" in the East China Sea Shelf Basin. During the Late Paleocene, the Pacific Plate margin migrated eastward along with development of the Philippine Ocean Plate, and the tectonic setting of the Lishui Sag gradually turned into a passive continental margin. Detrital sources included both orogenic continental blocks and continental island arcs, and the parent rocks are primarily felsic volcanic rocks and granites.展开更多
To investigate the thermo-rheological structure and passive continental margin rifting in the Qiongdongnan Basin(QDNB),thermo-rheological models of two profiles across the western and eastern QDNB are presented.The co...To investigate the thermo-rheological structure and passive continental margin rifting in the Qiongdongnan Basin(QDNB),thermo-rheological models of two profiles across the western and eastern QDNB are presented.The continental shelf of western QDNB,having the lowest crustal extension factor,is recognized as the initial non-uniform extension crust model.This regime is referred to as the jelly sandwich-1(JS-1)regime,having a lower crustal ductile layer.The oceanward part of the western QDNB changes from the relatively strong JS-1 to the weak crème brûlée-1(CB-1)regime with a significantly thinned lower crust.However,the crustal extension in the eastern QDNB is significantly higher than that in the western QDNB,with conjugate faults extending deep into the lower crust.The central depression zone of the eastern QDNB is defined as the much stronger JS-2 regime,having a brittle deformation across the entire crust and upper mantle and characteristics of a cold and rigid oceanic crust.Unlike the widespread lower crustal high-velocity layers(HVLs)in the northern margin of the South China Sea,the HVLs are confined to the lower crustal base of the central depression zone of the QDNB.The HVLs of QDNB are the results of non-uniform extension with mantle underplating during the lower crustal-necking stage,which is facilitated by the lower crustal ductile layer and derived by mantle lat-eral flowing.The gigantic mantle low-velocity zone related to the Red River Fault should be a necessary factor for the east-west differential margin rifting process of QDNB,which may drive the lateral flowing in the mantle.展开更多
The Ryukyu trench-arc system can be divided into two types according to its subduction model. The normal subduction in the northern part of the Philippine Sea plate creates a hinge sedimentary wedge with large deforma...The Ryukyu trench-arc system can be divided into two types according to its subduction model. The normal subduction in the northern part of the Philippine Sea plate creates a hinge sedimentary wedge with large deformation at the collision front, while the oblique subduction in the southern part gives rise to a smaller accretion with small deformation than that in the northern part. The mechanisms that cause the distinction between these two types have been analysed and calculated by using gravity data based on the lithosphere rheology and the stress state of the lithosphere in the subduction boundary. The two types of subduction model are associated with the internal extension in the southern Okinawa Trough and the small extension in the northern part. The difference of the stress state between the two types of subduction model is also manifested in other tectonic features, such as topography, volcanic activity and crust movement. Modeling bathymetric and gravity data from this area suggests that the oblique subduction of low angle, together with smooth geometry of the overlying plate crust, results in small stress released on the south of the trench by the subduction plate. The intraplate faults in the southern Okinawa Trough behind the trench stand in surplus intensive stress. On the other hand, the normal subduction of high angle, together with strong undulation geometry of the overlying crust, results in more intensive stress released in the northern Ryukyu Trench than that in the south. The intraplate faults in the northern Okinawa Trough behind the northern Ryukyu Trench stand in small stress.展开更多
基金supported by the National Key R&D Program of China(No.2021YFC2801200)the National Natural Science Foundation of China(No.42076224)the Fundamental Research Funds for the Central Universities(No.201964015)。
文摘The acquisition of seabed physical parameters is one of the focuses of marine acoustic researches.However,the activesource ocean bottom seismometer(OBS)detection method in the marine geophysical research is rarely used to acquire seabed physical parameters,and less work is performed in the Arctic.In this study,two active-source OBS data collected from the 9th and 11th Chinese National Arctic Research Expedition(CHINARE)are selected to obtain the physical parameters of seabed sediments.Two kinds of energy spark are used as the active sources,while the cost function inversion method is used based on the arrival time difference between the reflected and direct waves.The thickness and sound velocity of the sediment layers are obtained by inversion,and the empirical formula is used to calculate the physical parameters of the seabed sediment,which are compared with the measured results.The cost function inversion method based on the time difference of arrival of the reflected and direct waves is tested to be effective and feasible in the inversion of seabed parameters from active-source OBS data.The method is further applied to obtain the physical parameters of Chukchi seabed sediments,which provides the idea and reference for the application of marine geophysical activesource OBS detection technology in the inversion of polar seabed physical parameters.
基金supported by the Fundamental Research Funds for the Central Universities of Ocean University of China(201413005)a China National Science and Technology Major Project(2011ZX05023003)Shanghai Branch,China National Offshore Oil Co.,Ltd.(CNOOC)
文摘The Lishui Sag, in the East China Sea Shelf Basin, is rich in hydrocarbons, with the major hydrocarbon-bearing layers being the Paleocene Mingyuefeng clastic rocks. Analysis of the implicit geologic background information of these Paleocene clastic rocks using petrological and geochemical methods has significant practical importance. These Paleocene sandstones are mainly lithic arenite, lithic arkose and greywacke, composed of K-feldspar, plagioclase, authigenic clays, silica and carbonates. As continental deposits, Yueguifeng clastic rocks have high aluminosilicate and mafic detritus contents, while the Lingfeng and Mingyuefeng Formations are rich in silica due to an oscillating coastal marine depositional environment. The major element contents of these Paleocene sandstones are low and have a concentrated distribution, indicating that the geochemical composition is non-epigenetic, transformed by sedimentary processes and diagenesis. The Yueguifeng detritus comprises recycled sediments, controlled by moderate weathering and erosion, while the Lingfeng and Mingyuefeng detritus is interpreted as primarily first-cycle materials due to low chemical weathering. In the Late Cretaceous to Early Paleocene, the Pacific Plate began subducting under the Eurasian Plate, causing an orogeny by plate collision and magma eruption due to the melting of subducted oceanic crust. This resulted in the dual tectonic settings of "active margin" and "continental island arc" in the East China Sea Shelf Basin. During the Late Paleocene, the Pacific Plate margin migrated eastward along with development of the Philippine Ocean Plate, and the tectonic setting of the Lishui Sag gradually turned into a passive continental margin. Detrital sources included both orogenic continental blocks and continental island arcs, and the parent rocks are primarily felsic volcanic rocks and granites.
基金supported by the National Natural Science Foundation of China(Nos.41530963,41176038 and 91858215).
文摘To investigate the thermo-rheological structure and passive continental margin rifting in the Qiongdongnan Basin(QDNB),thermo-rheological models of two profiles across the western and eastern QDNB are presented.The continental shelf of western QDNB,having the lowest crustal extension factor,is recognized as the initial non-uniform extension crust model.This regime is referred to as the jelly sandwich-1(JS-1)regime,having a lower crustal ductile layer.The oceanward part of the western QDNB changes from the relatively strong JS-1 to the weak crème brûlée-1(CB-1)regime with a significantly thinned lower crust.However,the crustal extension in the eastern QDNB is significantly higher than that in the western QDNB,with conjugate faults extending deep into the lower crust.The central depression zone of the eastern QDNB is defined as the much stronger JS-2 regime,having a brittle deformation across the entire crust and upper mantle and characteristics of a cold and rigid oceanic crust.Unlike the widespread lower crustal high-velocity layers(HVLs)in the northern margin of the South China Sea,the HVLs are confined to the lower crustal base of the central depression zone of the QDNB.The HVLs of QDNB are the results of non-uniform extension with mantle underplating during the lower crustal-necking stage,which is facilitated by the lower crustal ductile layer and derived by mantle lat-eral flowing.The gigantic mantle low-velocity zone related to the Red River Fault should be a necessary factor for the east-west differential margin rifting process of QDNB,which may drive the lateral flowing in the mantle.
文摘The Ryukyu trench-arc system can be divided into two types according to its subduction model. The normal subduction in the northern part of the Philippine Sea plate creates a hinge sedimentary wedge with large deformation at the collision front, while the oblique subduction in the southern part gives rise to a smaller accretion with small deformation than that in the northern part. The mechanisms that cause the distinction between these two types have been analysed and calculated by using gravity data based on the lithosphere rheology and the stress state of the lithosphere in the subduction boundary. The two types of subduction model are associated with the internal extension in the southern Okinawa Trough and the small extension in the northern part. The difference of the stress state between the two types of subduction model is also manifested in other tectonic features, such as topography, volcanic activity and crust movement. Modeling bathymetric and gravity data from this area suggests that the oblique subduction of low angle, together with smooth geometry of the overlying plate crust, results in small stress released on the south of the trench by the subduction plate. The intraplate faults in the southern Okinawa Trough behind the trench stand in surplus intensive stress. On the other hand, the normal subduction of high angle, together with strong undulation geometry of the overlying crust, results in more intensive stress released in the northern Ryukyu Trench than that in the south. The intraplate faults in the northern Okinawa Trough behind the northern Ryukyu Trench stand in small stress.