Vertical differential structural deformation(VDSD),one of the most significant structural characteristics of strike-slip fault zones(SSFZs)in the Shunbei area,is crucial for understanding deformation in the SSFZ and i...Vertical differential structural deformation(VDSD),one of the most significant structural characteristics of strike-slip fault zones(SSFZs)in the Shunbei area,is crucial for understanding deformation in the SSFZ and its hydrocarbon accumulation significance.Based on drilling data and high-precision 3-D seismic data,we analyzed the geometric and kinematic characteristics of the SSFZs in the Shunbei area.Coupled with the stratification of the rock mechanism,the structural deformations of these SSFZs in different formations were differentiated and divided into four deformation layers.According to comprehensive structural interpretations and comparisons,three integrated 3-D structural models could describe the VDSD of these SSFZs.The time-space coupling of the material basis(rock mechanism stratification),changing dynamic conditions(e.g.,changing stress-strain states),and special deformation mechanism of the en echelon normal fault array uniformly controlled the formation of the VDSD in the SSFZs of the Shunbei area.The VDSD of the SSFZs in this area controlled the entire hydrocarbon accumulation process.Multi-stage structural superimposing deformation influenced the hydrocarbon migration,accumulation,distribution,preservation,and secondary adjustments.展开更多
Intervals of soft-sediment deformation structures are well-exposed in Jurassic lacustrine deposits in the western Qaidamu basin. Through field observation, many soft-sediment deformation structures can be identified, ...Intervals of soft-sediment deformation structures are well-exposed in Jurassic lacustrine deposits in the western Qaidamu basin. Through field observation, many soft-sediment deformation structures can be identified, such as convoluted bedding, liquefied sand veins, load and flame structures, slump structures and sliding-overlapping structures. Based on their genesis, soft-sediment deformation structures can be classified as three types： seismic induced structures, vertical loading structures, and horizontal shear structures. Based on their geometry and genesis analysis, they are seismic-induced structures. According to the characteristics of convoluted bedding structures and liquefied sand veins, it can be inferred that there were earthquakes greater than magnitude 6 in the study area during the middle Jurassic. Furthermore, the study of the slump structures and sliding- overlapping structures indicates that there was a southeastern slope during the middle Jurassic. Since the distance from the study area to the Altyn Mountain and the Altyn fault is no more than 10km, it can be also inferred that the Altyn Mountain existed then and that the AItyn strike-slip fault was active during the middle Jurassic.展开更多
The subtle strike-slip tectonic deformation and its relationship to deposition, overpressure and hydrocarbon migration were studied on the basis of systematic sorting of tectonic data.(1) The local T(tension) fracture...The subtle strike-slip tectonic deformation and its relationship to deposition, overpressure and hydrocarbon migration were studied on the basis of systematic sorting of tectonic data.(1) The local T(tension) fractures derived from sinistral strike-slip process were formed before 10.5 Ma, large in number in the nose structure of the eastern slope, and reactivated episodically under the effect of fluid overpressure in the late stage, they served as dominant vertical hydrocarbon migration paths in the slope area of basin.(2) The dextral strike-slip extension was conducive to the increase of depositional rate and formation of regional under-compacted seal, and induced generation of local T fractures which triggered the development of diapirs; in turn, the development of diapirs made T fractures grow in size further.(3) The sinistral strike-slip process weakened after 10.5 Ma, causing tectonic movement characterized by compression in the north and rotational extension in the south, and the uplift and erosion of strata in Hanoi sag and a surge in clastics supply for south Yinggehai sag. Finally, migrating slope channelized submarine fans and superimposed basin floor fans were developed respectively on the asymmetrical east and west slopes of the Yinggehai sag.展开更多
Transform faults represent one of the three primary types of plate boundaries in plate tectonics theory and constitute an essential component of this framework.In general,they are classified into oceanic and continent...Transform faults represent one of the three primary types of plate boundaries in plate tectonics theory and constitute an essential component of this framework.In general,they are classified into oceanic and continental transform faults based on the nature of their separated plates.Owing to significant differences in properties between continental and oceanic lithospheres,continental transform faults exhibit more complex structures than their oceanic counterparts.Continental transform faults are strike-slip boundaries where stress and strain are highly concentrated.They typically extend for hundreds to thousands of kilometers and have experienced tens to hundreds of kilometers of strike-slip displacement.These faults may appear as a single master fault or as complex fault systems with multiple branches.Their deep structures and deformation patterns at varying depths offer critical insights into the structure and rheological behavior of the continental lithosphere.Imaging fine-scale structures of continental transform faults via geophysical methods is crucial for understanding their nature and evolution.Seismic anisotropy results provide key constraints on their deep deformation characteristics.This paper reviews geophysical studies from typical continental transform fault regions and investigates their deep structure and deformation mechanisms by integrating geological and geodetic observations.Although these fault systems are structurally diverse,several common features emerge.(1)Nearly all continental transform faults cut through the entire crust and extend into the upper mantle,with significant seismic anisotropy observed within the fault zones.(2)Regardless of whether the fault is a single narrow structure or a branching system,uppercrustal segments typically form narrow zones of strain concentration where brittle friction accommodates slip and seismicity is concentrated.The shear zone broadens with depth,reaching tens of kilometers in width within the lithospheric mantle.(3)The width of a continental transform fault correlates with the nature of the lithosphere it cross-cuts.Narrow shear zones form in rigid and ancient lithosphere,otherwise,broader distributed deformation occurs.(4)Non-strike-slip components(compression or tension)significantly influence fault zone complexity.Recent ocean drilling programs have advanced understanding of oceanic transform faults,yet knowledge of continental transform fault structure and evolution remains limited.Advances in seismic imaging and observational techniques will enable higher-resolution characterization of these faults,providing new constraints on their seismic behavior and earthquake migration patterns.展开更多
基金financially supported by the China Petroleum&Chemical Corporation(SINOPEC)(Grant No.P18047-2)the National Natural Science Foundation of China(Grant No.U19B6003-01)the National Key Research and Development Program of China(Grant No.2017YFC0601405)。
文摘Vertical differential structural deformation(VDSD),one of the most significant structural characteristics of strike-slip fault zones(SSFZs)in the Shunbei area,is crucial for understanding deformation in the SSFZ and its hydrocarbon accumulation significance.Based on drilling data and high-precision 3-D seismic data,we analyzed the geometric and kinematic characteristics of the SSFZs in the Shunbei area.Coupled with the stratification of the rock mechanism,the structural deformations of these SSFZs in different formations were differentiated and divided into four deformation layers.According to comprehensive structural interpretations and comparisons,three integrated 3-D structural models could describe the VDSD of these SSFZs.The time-space coupling of the material basis(rock mechanism stratification),changing dynamic conditions(e.g.,changing stress-strain states),and special deformation mechanism of the en echelon normal fault array uniformly controlled the formation of the VDSD in the SSFZs of the Shunbei area.The VDSD of the SSFZs in this area controlled the entire hydrocarbon accumulation process.Multi-stage structural superimposing deformation influenced the hydrocarbon migration,accumulation,distribution,preservation,and secondary adjustments.
基金The National Natural Science Fund(No:41172093)the research fund(No:2003042500820060425509)for the doctoral program of higher education from Ministry of Education for their financial support
文摘Intervals of soft-sediment deformation structures are well-exposed in Jurassic lacustrine deposits in the western Qaidamu basin. Through field observation, many soft-sediment deformation structures can be identified, such as convoluted bedding, liquefied sand veins, load and flame structures, slump structures and sliding-overlapping structures. Based on their genesis, soft-sediment deformation structures can be classified as three types： seismic induced structures, vertical loading structures, and horizontal shear structures. Based on their geometry and genesis analysis, they are seismic-induced structures. According to the characteristics of convoluted bedding structures and liquefied sand veins, it can be inferred that there were earthquakes greater than magnitude 6 in the study area during the middle Jurassic. Furthermore, the study of the slump structures and sliding- overlapping structures indicates that there was a southeastern slope during the middle Jurassic. Since the distance from the study area to the Altyn Mountain and the Altyn fault is no more than 10km, it can be also inferred that the Altyn Mountain existed then and that the AItyn strike-slip fault was active during the middle Jurassic.
基金Supported by the China National Science and Technology Major Project(2016ZX05024-005)
文摘The subtle strike-slip tectonic deformation and its relationship to deposition, overpressure and hydrocarbon migration were studied on the basis of systematic sorting of tectonic data.(1) The local T(tension) fractures derived from sinistral strike-slip process were formed before 10.5 Ma, large in number in the nose structure of the eastern slope, and reactivated episodically under the effect of fluid overpressure in the late stage, they served as dominant vertical hydrocarbon migration paths in the slope area of basin.(2) The dextral strike-slip extension was conducive to the increase of depositional rate and formation of regional under-compacted seal, and induced generation of local T fractures which triggered the development of diapirs; in turn, the development of diapirs made T fractures grow in size further.(3) The sinistral strike-slip process weakened after 10.5 Ma, causing tectonic movement characterized by compression in the north and rotational extension in the south, and the uplift and erosion of strata in Hanoi sag and a surge in clastics supply for south Yinggehai sag. Finally, migrating slope channelized submarine fans and superimposed basin floor fans were developed respectively on the asymmetrical east and west slopes of the Yinggehai sag.
基金supported by the National Key R&D Program of China(Grant No.2022YFC3003701)the National Natural Science Foundation of China(Grant No.42274061)。
文摘Transform faults represent one of the three primary types of plate boundaries in plate tectonics theory and constitute an essential component of this framework.In general,they are classified into oceanic and continental transform faults based on the nature of their separated plates.Owing to significant differences in properties between continental and oceanic lithospheres,continental transform faults exhibit more complex structures than their oceanic counterparts.Continental transform faults are strike-slip boundaries where stress and strain are highly concentrated.They typically extend for hundreds to thousands of kilometers and have experienced tens to hundreds of kilometers of strike-slip displacement.These faults may appear as a single master fault or as complex fault systems with multiple branches.Their deep structures and deformation patterns at varying depths offer critical insights into the structure and rheological behavior of the continental lithosphere.Imaging fine-scale structures of continental transform faults via geophysical methods is crucial for understanding their nature and evolution.Seismic anisotropy results provide key constraints on their deep deformation characteristics.This paper reviews geophysical studies from typical continental transform fault regions and investigates their deep structure and deformation mechanisms by integrating geological and geodetic observations.Although these fault systems are structurally diverse,several common features emerge.(1)Nearly all continental transform faults cut through the entire crust and extend into the upper mantle,with significant seismic anisotropy observed within the fault zones.(2)Regardless of whether the fault is a single narrow structure or a branching system,uppercrustal segments typically form narrow zones of strain concentration where brittle friction accommodates slip and seismicity is concentrated.The shear zone broadens with depth,reaching tens of kilometers in width within the lithospheric mantle.(3)The width of a continental transform fault correlates with the nature of the lithosphere it cross-cuts.Narrow shear zones form in rigid and ancient lithosphere,otherwise,broader distributed deformation occurs.(4)Non-strike-slip components(compression or tension)significantly influence fault zone complexity.Recent ocean drilling programs have advanced understanding of oceanic transform faults,yet knowledge of continental transform fault structure and evolution remains limited.Advances in seismic imaging and observational techniques will enable higher-resolution characterization of these faults,providing new constraints on their seismic behavior and earthquake migration patterns.
