Located at the northwest continental slope of the South China Sea, the Qiongdongnan Basin bears valley-shaped bathymetry deepening toward east. It is separated from the Yinggehai Basin through NW-trending Indo-China-R...Located at the northwest continental slope of the South China Sea, the Qiongdongnan Basin bears valley-shaped bathymetry deepening toward east. It is separated from the Yinggehai Basin through NW-trending Indo-China-Red River shear zone, and connected with NW subsea basin through the Xisha Trough. Along with the rapid progress of the deepwater exploration, large amounts of high resolution geophysical and geological data were accumulated. Scientific researches about deepwater basins kept revealing brand new tectonic and sedimentary discoveries. In order to summarize the structural features and main controlling factors of the deepwater Qiongdongnan Basin, a series of researches on basin architecture, fault activities, tectonic deformation and evolution were carried out. In reference to analogue modeling experiments, a tectonic situation and a basin formation mechanism were discussed. The researches indicate that：the northern boundary of the Qiongdongnan Basin is strongly controlled by No. 2 fault. The overlapping control of two stress fields from the east and the west made the central depression zone extremely thinned. Combined with the changed stress field, the segmentation of a preexisting weakness zone made the sags in the east experiencing different rifting histories from the west ones. The NE-trending west segment of the Qiongdongnan Basin experienced strong rifting during Eocene, while the roughly EW-trending sags in the east segment show strong rifting during late Eocene and early Oligocene. Local structures such as NW-trending basal fault and inherited uplifts controlled the lateral segmentation. So first order factors such as regional stress field and preexisting weakness zone controlled the basin zonation, while the second order factors determined the segmentation from east to west.展开更多
Based on field observations and rheology analysis,we perform one analogue experiment and remold the 3D structural frame of Tongling deposit concentrating area firstly.Then we disassemble and dialyze the 3D structures ...Based on field observations and rheology analysis,we perform one analogue experiment and remold the 3D structural frame of Tongling deposit concentrating area firstly.Then we disassemble and dialyze the 3D structures of the model using the methods of"slicing"and"stripping".A series of sliced planes vertical to the fold hinges show similar landscapes of that in the drill hole profiles.Meanwhile,layer stripping analysis indicates that the deformation features of each layer in the model are qualitatively analogical to those obtained from field observations.Through contrasting the 3D structure between the experimental model and the field phenomena,we verify the following 3D deformation features of the caprock in this area:(1)the Tongling area mainly consists of three series of NE S-typed fold groups;(2)in the uniform stress field,the incoherent folds universally develop in different positions,along different axes as well as in different strata;(3)the faults propagate upward which are mostly inter-bedded detachment faults,while the fold amplitudes decrease while going deeper;and(4)the folds and cleavages are highly developed in the Silurian System indicating that the deformation effect of the Indosin-ian-Yanshanian structural layer terminates at this layer,which suggests that the Silurian System is the crucial layer for the inversion between brittle and plastic deformation domains and the underlying strata are subject to the control of another deformation system with distinct properties.展开更多
基金The Major National Science and Technology Programs of China under contract No.2011ZX05025-003-005the Joint Program of the National Science Foundation and Guangdong Province under contract No.U1301233
文摘Located at the northwest continental slope of the South China Sea, the Qiongdongnan Basin bears valley-shaped bathymetry deepening toward east. It is separated from the Yinggehai Basin through NW-trending Indo-China-Red River shear zone, and connected with NW subsea basin through the Xisha Trough. Along with the rapid progress of the deepwater exploration, large amounts of high resolution geophysical and geological data were accumulated. Scientific researches about deepwater basins kept revealing brand new tectonic and sedimentary discoveries. In order to summarize the structural features and main controlling factors of the deepwater Qiongdongnan Basin, a series of researches on basin architecture, fault activities, tectonic deformation and evolution were carried out. In reference to analogue modeling experiments, a tectonic situation and a basin formation mechanism were discussed. The researches indicate that：the northern boundary of the Qiongdongnan Basin is strongly controlled by No. 2 fault. The overlapping control of two stress fields from the east and the west made the central depression zone extremely thinned. Combined with the changed stress field, the segmentation of a preexisting weakness zone made the sags in the east experiencing different rifting histories from the west ones. The NE-trending west segment of the Qiongdongnan Basin experienced strong rifting during Eocene, while the roughly EW-trending sags in the east segment show strong rifting during late Eocene and early Oligocene. Local structures such as NW-trending basal fault and inherited uplifts controlled the lateral segmentation. So first order factors such as regional stress field and preexisting weakness zone controlled the basin zonation, while the second order factors determined the segmentation from east to west.
基金the National NaturalScience Foundation of China(Grant No.40234051)the Special Plansof Science and Technology of Land Resource Department(Grant No.20010103)+2 种基金the National Important Layout ltems of Basic ResearchDevelopment(Grant No.1999043206)the Fostering Plan Fund forBeyond-Century Excellent Talentthe Key Project of Science and Technology Research(O3178)of the Ministry of Education.
文摘Based on field observations and rheology analysis,we perform one analogue experiment and remold the 3D structural frame of Tongling deposit concentrating area firstly.Then we disassemble and dialyze the 3D structures of the model using the methods of"slicing"and"stripping".A series of sliced planes vertical to the fold hinges show similar landscapes of that in the drill hole profiles.Meanwhile,layer stripping analysis indicates that the deformation features of each layer in the model are qualitatively analogical to those obtained from field observations.Through contrasting the 3D structure between the experimental model and the field phenomena,we verify the following 3D deformation features of the caprock in this area:(1)the Tongling area mainly consists of three series of NE S-typed fold groups;(2)in the uniform stress field,the incoherent folds universally develop in different positions,along different axes as well as in different strata;(3)the faults propagate upward which are mostly inter-bedded detachment faults,while the fold amplitudes decrease while going deeper;and(4)the folds and cleavages are highly developed in the Silurian System indicating that the deformation effect of the Indosin-ian-Yanshanian structural layer terminates at this layer,which suggests that the Silurian System is the crucial layer for the inversion between brittle and plastic deformation domains and the underlying strata are subject to the control of another deformation system with distinct properties.
