The Karatau fault is one of the important strike-slip faults in central Asia,and the South Turgay Basin is located towards its northern end.Detailed seismic interpretation indicated that the strikeslip tectonism of th...The Karatau fault is one of the important strike-slip faults in central Asia,and the South Turgay Basin is located towards its northern end.Detailed seismic interpretation indicated that the strikeslip tectonism of the Karatau fault weakened gradually from west to east in the South Turgay Basin.Typical flower structures developed on the section,and strike-slip faults showed an echelon pattern on planar view.The Karatau strike-slip fault affected the South Turgay Basin in two periods：（1） The South Turgay strike-slip pull-apart rift basin formed as a result of regional extensive stress in the Early-Middle Jurassic,characterized by the juxtaposition of horsts and grabens.The formation of horsts provided favorable reservoir spaces for later hydrocarbon accumulation,and different filling stages of grabens controlled different reservoir-forming factors in grabens.（2） Two stages of tectonic inversion occurred in the Late Jurassic and Late Cretaceous and played a crucial role in the final shape of the structure in the South Turgay Basin.The oil and gas migrated to form reservoirs and mainly concentrated in the horsts,graben slopes and in both sides of the strike-slip fault zone.In the case of the degree of accumulation of petroleum,the factor explaining why horsts are better than grabens is the strike-slip pull-apart of the South Turgay Basin,and the structure inversion of the South Turgay Basin explains why the west graben is better than the east one.Overall,the Karatau strike-slip fault played a very important role in the formation of the South Turgay Basin and its hydrocarbon accumulations.展开更多
The Talas Fergana/Karatau Fault,is a major tectonic boundary separating the Kazakh-Turan domain to the west from the Tian Shan domain to the east.During the Jurassic,movements along the fault led to the opening of sev...The Talas Fergana/Karatau Fault,is a major tectonic boundary separating the Kazakh-Turan domain to the west from the Tian Shan domain to the east.During the Jurassic,movements along the fault led to the opening of several basins.Still,the Mesozoic kinematics of the fault and the geodynamic mechanism that led to the opening of these basins are largely unconstrained.Located at its southwestern termination,the Yarkand-Fergana Basin is certainly the best exposed and however still poorly understood.In this study,we provide new sedimentological description of the Jurassic series from the northern part of the Yarkand-Fergana Basin as well as new palynological data.Following a Middle-Late Triassic period dominated by regional erosion,the onset of sedimentation in the Yarkand-Fergana Basin occurred during the Sinemurian(?)-Pliensbachian.The basin opened as a half graben controlled by the Talas Fergana/Karatau Fault and separated from the Fergana Basin by basement highs.Extension persisted during the late Pliensbachian-Middle Jurassic,leading to a general widening of the YarkandFergana Basin.Finally,Late Jurassic-Early Cretaceous renewed tectonic activity in the area led to the inversion of the north Yarkand-Fergana Basin.The Early to Middle Jurassic timing of development of the Yarkand-Fergana Basin suggests that the coeval movements along the Talas Fergana/Karatau Fault are not associated to the collision of the Qiangtang block along the southern margin of Eurasia.We favor the hypothesis of an opening controlled by transtension related to far field effects of back-arc extension along the Neo-Tethys subduction zone to the west.展开更多
基金supported by the Major National Science and Technology Projects of China (No. 2008ZX05029-002)CNPC Research Topics of China (No.07B60101)
文摘The Karatau fault is one of the important strike-slip faults in central Asia,and the South Turgay Basin is located towards its northern end.Detailed seismic interpretation indicated that the strikeslip tectonism of the Karatau fault weakened gradually from west to east in the South Turgay Basin.Typical flower structures developed on the section,and strike-slip faults showed an echelon pattern on planar view.The Karatau strike-slip fault affected the South Turgay Basin in two periods：（1） The South Turgay strike-slip pull-apart rift basin formed as a result of regional extensive stress in the Early-Middle Jurassic,characterized by the juxtaposition of horsts and grabens.The formation of horsts provided favorable reservoir spaces for later hydrocarbon accumulation,and different filling stages of grabens controlled different reservoir-forming factors in grabens.（2） Two stages of tectonic inversion occurred in the Late Jurassic and Late Cretaceous and played a crucial role in the final shape of the structure in the South Turgay Basin.The oil and gas migrated to form reservoirs and mainly concentrated in the horsts,graben slopes and in both sides of the strike-slip fault zone.In the case of the degree of accumulation of petroleum,the factor explaining why horsts are better than grabens is the strike-slip pull-apart of the South Turgay Basin,and the structure inversion of the South Turgay Basin explains why the west graben is better than the east one.Overall,the Karatau strike-slip fault played a very important role in the formation of the South Turgay Basin and its hydrocarbon accumulations.
文摘The Talas Fergana/Karatau Fault,is a major tectonic boundary separating the Kazakh-Turan domain to the west from the Tian Shan domain to the east.During the Jurassic,movements along the fault led to the opening of several basins.Still,the Mesozoic kinematics of the fault and the geodynamic mechanism that led to the opening of these basins are largely unconstrained.Located at its southwestern termination,the Yarkand-Fergana Basin is certainly the best exposed and however still poorly understood.In this study,we provide new sedimentological description of the Jurassic series from the northern part of the Yarkand-Fergana Basin as well as new palynological data.Following a Middle-Late Triassic period dominated by regional erosion,the onset of sedimentation in the Yarkand-Fergana Basin occurred during the Sinemurian(?)-Pliensbachian.The basin opened as a half graben controlled by the Talas Fergana/Karatau Fault and separated from the Fergana Basin by basement highs.Extension persisted during the late Pliensbachian-Middle Jurassic,leading to a general widening of the YarkandFergana Basin.Finally,Late Jurassic-Early Cretaceous renewed tectonic activity in the area led to the inversion of the north Yarkand-Fergana Basin.The Early to Middle Jurassic timing of development of the Yarkand-Fergana Basin suggests that the coeval movements along the Talas Fergana/Karatau Fault are not associated to the collision of the Qiangtang block along the southern margin of Eurasia.We favor the hypothesis of an opening controlled by transtension related to far field effects of back-arc extension along the Neo-Tethys subduction zone to the west.
