Based on the interpretation of 3D seismic data and structural mapping we analyzed the geometry and kinematics of the fault system and validated the expression of the"Tan-Lu Fracture Zone"in the West Sag of L...Based on the interpretation of 3D seismic data and structural mapping we analyzed the geometry and kinematics of the fault system and validated the expression of the"Tan-Lu Fracture Zone"in the West Sag of Liaohe Depression,Bohaiwan basin province.The Cenozoic structural deformation within the West Sag of Liaohe Depression can be divided into extensional structure system and dextral structure system.The extensional system is constituted by numerous NNE-NE trending Paleogene normal faults,where the Taian-Dawa fault(F1)is the master boundary fault(MBF)dominating the deposition during Paleogene so that the sag shows a complex half-graben with"boundary fault in the east and overlap in the west".The dextral system is constituted by 2–3 dextral basement faults in NNE-NE trending(F2,F3,F4)and associated structure,and the time of structural action started in Oligocene and continued to Quarternary so that some associated secondary faults of the dextral system cut off the Neogene and Quaternary.Under the influence of the position and attitude of NNE-NE trending basement strike-slip faults,the central north part and the south part of the West Sag show obviously different structural features.The former appears to be a complex"graben"structure limited by the reversed strike-slip fault in the west and bounded by the inverted normal fault in the east,the latter remains the complex half-graben structure with"boundary fault in the east and overlap in the west",and the graben was mildly reconstructed by one or two normal strike-slip faults.The dextral system within the West Sag is the element of the west branch fault of the Tan-Lu Fracture Zone,which is a deep fracture zone extending along the east of the Liaodongwan Gulf.The deep fracture zone branches off into two separate faults within the Liaohe Depression.The east branch goes through from northern part of the Liaodongwan Gulf to the East Sag of Liaohe Depression and links with the Denghua-Mishan Fault near Shenyang,and the west branch passes from northern part of the Liaodongwan Gulf to the West Sag and Damintun Sag of Liaohe Depression and links with the Yilan-Yitong Fault.The principal displacement zone of the west branch of the Tan-Lu Fracture Zone cuts off the master extensional fault(F1)within the West Sag of Liaohe Depression and induces many cover faults in EW trending within the Neogene and Quaternary.展开更多
The Neoproterozoic Kangdian Rift Basin is a continental rift basin in the western Yangtze Continent.Determining its time of opening and subsequent filling pattern is an important aspect of understanding the formation ...The Neoproterozoic Kangdian Rift Basin is a continental rift basin in the western Yangtze Continent.Determining its time of opening and subsequent filling pattern is an important aspect of understanding the formation and evolution of the Yangtze Continent,South China.The Luliang Formation is the early filling in the eastern part of this rift basin,and its deposition age and filling sequence are significant for studies of the regional stratigraphic correlation,opening time,and filling pattern of this basin.Having been correlated to the upper part of the Mesoproterozoic Kunyang Group or to the Neoproterozoic Chengjiang Formation,the age and regional stratigraphic correlation of the Luliang Formation have long been uncertain.This is due to a lack of reliable absolute age constraints.To address this issue,the first zircon SHRIMP U-Pb geochronology has been established for this formation,yielding two high-precision isotopic ages of 818.6±9.2 and 805±14 Ma for the tuff layers at the bottoms of the lower and upper members of the Luliang Formation,respectively.Given the error factor,the bottom age of the lower member of the Luliang Formation can be interpreted as ca.820 Ma,corresponding to the bottom age of the lower part of the Banxi Group,which is the early filling of the Neoproterozoic Xianggui Rift Basin,a representative basin of the Neoproterozoic rift basins in the Yangtze Continent,South China.The bottom age of the upper member of the Luliang Formation can be interpreted as ca.800±5 Ma,corresponding to the bottom age of the Chengjiang Formation in the western part of the Neoproterozoic Kangdian Rift Basin and also corresponding to the bottom age of the upper part of the Banxi Group in the Neoproterozoic Xianggui Rift Basin.These ages indicate that the Neoproterozoic Kangdian Rift Basin shares the same opening time and filling sequences as those of the other Neoproterozoic rift basins in South China.Basin analysis shows that the Neoproterozoic Kangdian Rift Basin is a typical half-graben basin,with its main boundary fault in the west and basin center in the east.This basin consisted of mini unidirectional half-graben basins in its juvenile stage and simplified to become a large united half-graben basin in its mature stage,i.e.,a supradetachment basin.展开更多
基金supported by National Natural Science Foundation of China(Grant No.90914006)Ministry of Science and Technology of China(Grant No.2009ZX05009-001)State Key Lab of Petroleum Resources and Prospecting(Grant No.PRPDX2008-03)
文摘Based on the interpretation of 3D seismic data and structural mapping we analyzed the geometry and kinematics of the fault system and validated the expression of the"Tan-Lu Fracture Zone"in the West Sag of Liaohe Depression,Bohaiwan basin province.The Cenozoic structural deformation within the West Sag of Liaohe Depression can be divided into extensional structure system and dextral structure system.The extensional system is constituted by numerous NNE-NE trending Paleogene normal faults,where the Taian-Dawa fault(F1)is the master boundary fault(MBF)dominating the deposition during Paleogene so that the sag shows a complex half-graben with"boundary fault in the east and overlap in the west".The dextral system is constituted by 2–3 dextral basement faults in NNE-NE trending(F2,F3,F4)and associated structure,and the time of structural action started in Oligocene and continued to Quarternary so that some associated secondary faults of the dextral system cut off the Neogene and Quaternary.Under the influence of the position and attitude of NNE-NE trending basement strike-slip faults,the central north part and the south part of the West Sag show obviously different structural features.The former appears to be a complex"graben"structure limited by the reversed strike-slip fault in the west and bounded by the inverted normal fault in the east,the latter remains the complex half-graben structure with"boundary fault in the east and overlap in the west",and the graben was mildly reconstructed by one or two normal strike-slip faults.The dextral system within the West Sag is the element of the west branch fault of the Tan-Lu Fracture Zone,which is a deep fracture zone extending along the east of the Liaodongwan Gulf.The deep fracture zone branches off into two separate faults within the Liaohe Depression.The east branch goes through from northern part of the Liaodongwan Gulf to the East Sag of Liaohe Depression and links with the Denghua-Mishan Fault near Shenyang,and the west branch passes from northern part of the Liaodongwan Gulf to the West Sag and Damintun Sag of Liaohe Depression and links with the Yilan-Yitong Fault.The principal displacement zone of the west branch of the Tan-Lu Fracture Zone cuts off the master extensional fault(F1)within the West Sag of Liaohe Depression and induces many cover faults in EW trending within the Neogene and Quaternary.
基金supported by National Natural Science Foundation of China(Grant Nos.4103031541072088)China Geological Survey(Grant No.1212011121105)
文摘The Neoproterozoic Kangdian Rift Basin is a continental rift basin in the western Yangtze Continent.Determining its time of opening and subsequent filling pattern is an important aspect of understanding the formation and evolution of the Yangtze Continent,South China.The Luliang Formation is the early filling in the eastern part of this rift basin,and its deposition age and filling sequence are significant for studies of the regional stratigraphic correlation,opening time,and filling pattern of this basin.Having been correlated to the upper part of the Mesoproterozoic Kunyang Group or to the Neoproterozoic Chengjiang Formation,the age and regional stratigraphic correlation of the Luliang Formation have long been uncertain.This is due to a lack of reliable absolute age constraints.To address this issue,the first zircon SHRIMP U-Pb geochronology has been established for this formation,yielding two high-precision isotopic ages of 818.6±9.2 and 805±14 Ma for the tuff layers at the bottoms of the lower and upper members of the Luliang Formation,respectively.Given the error factor,the bottom age of the lower member of the Luliang Formation can be interpreted as ca.820 Ma,corresponding to the bottom age of the lower part of the Banxi Group,which is the early filling of the Neoproterozoic Xianggui Rift Basin,a representative basin of the Neoproterozoic rift basins in the Yangtze Continent,South China.The bottom age of the upper member of the Luliang Formation can be interpreted as ca.800±5 Ma,corresponding to the bottom age of the Chengjiang Formation in the western part of the Neoproterozoic Kangdian Rift Basin and also corresponding to the bottom age of the upper part of the Banxi Group in the Neoproterozoic Xianggui Rift Basin.These ages indicate that the Neoproterozoic Kangdian Rift Basin shares the same opening time and filling sequences as those of the other Neoproterozoic rift basins in South China.Basin analysis shows that the Neoproterozoic Kangdian Rift Basin is a typical half-graben basin,with its main boundary fault in the west and basin center in the east.This basin consisted of mini unidirectional half-graben basins in its juvenile stage and simplified to become a large united half-graben basin in its mature stage,i.e.,a supradetachment basin.
