The Makran accretionary wedge has the smallest subduction angle among any accretionary prism in the world. The factors controlling the spacing and morphological development of its deep thrust faults, as well as the fo...The Makran accretionary wedge has the smallest subduction angle among any accretionary prism in the world. The factors controlling the spacing and morphological development of its deep thrust faults, as well as the formation mechanism of shallow normal faults, remain unclear. Meanwhile, the factors affecting the continuity of plane faults must be comprehensively discussed. Clarifying the development characteristics and deformation mechanisms of the Makran accretionary wedge is crucial to effectively guide the exploration of gas hydrate deposits in the area. This study aims to interpret seismic data to identify typical structures in the Makran accretionary wedge, including deep imbricate thrust faults, shallow and small normal faults, wedge-shaped piggyback basins, mud diapirs with fuzzy and disorderly characteristics of reflection, décollements with a northward tilt of 1° – 2°, and large seamounts. Physical simulation-based experiments are performed to comprehensively analyze the results of the plane, section, and slices of the wedge. Results reveal that the distances between and shapes of thrust faults in the deep parts of the Makran accretionary wedge are controlled by the bottom décollement. The uplift of the thrust fault-related folds and the upwelling of the mud diapirs primarily contribute to the formation of small normal faults in the shallow part of the area. The mud diapirs originate from plastic material at the bottom, while those that have developed in the area near the trench are larger. Seamounts and mud diapirs break the continuity of fault plane distribution.展开更多
In the Gulf of Mexico and adjacent landmasses,faults are very complex,and their distribution is closely related to plate tectonics,ocean-land boundary,and former structure.The plane position of the faults can be ident...In the Gulf of Mexico and adjacent landmasses,faults are very complex,and their distribution is closely related to plate tectonics,ocean-land boundary,and former structure.The plane position of the faults can be identified by the maximum characteristic of the vertical derivative of the normalized vertical derivative of the total horizontal derivative(NVDR-THDR)of the Bouguer gravity anomaly.The apparent depth of the faults is inverted by the Bouguer gravity anomaly curvature property.Based on tectonic evolutionary processes and the plane distribution and apparent depth characteristics of the faults,a complete fault system for the Gulf of Mexico and adjacent areas has been established,including 102 faults.The apparent depths of 33 first-class faults are 16-20 km and for 69 second-class faults are 12-16 km.The F_(1-2)and F_(1-3)subduction fault zones are two caused by the subduction of the Cocos Plate into the old Yucatan and Chorti landmasses;F_(1-11)and F_(1-12)fault zones extend westward to the coast of Guatemala and do not extend into the continent;F_(1-17)and F_(1-20)faults,which control the boundary of the oceanic crust,do not extend southward into the continent.The fault system,which radiates in a"fan-shaped"structure as a whole,unfolds to the northeast.Faults of different nature and sizes are distributed in the Cocos Plate subduction zone,Continental,Gulf of Mexico,Yucatan old landmass and Caribbean Plate in NW,NNW,NS,NE and NEE directions.In the Gulf of Mexico region,the fault system is a comprehensive reflection of former tectonic movements,such as plate movement,drift of old landmasses and expansion of oceanic crusts.The first-class faults control the plate and ocean-continental boundaries.The second-class faults are subordinate to the first-class faults or related to the distribution of different sedimentary layers.展开更多
Research on the characteristics of faults and their evolutionary history since the Cretaceous in the Suhongtu-Dagu depressions can provide a theoretical basis for geological evaluation of the coal seams in the Suhongt...Research on the characteristics of faults and their evolutionary history since the Cretaceous in the Suhongtu-Dagu depressions can provide a theoretical basis for geological evaluation of the coal seams in the Suhongtu Formation in the northern-central region of the Yin’e Basin.Using 3-D seismic-logging inversion techniques,seismic stratigraphic calibration,stratigraphic sequence delineation,and thickness calculations on the Suhongtu-Dagu depressions were carried out to clarify the planar and profile distributions of the faults,as well as the evolutionary history of these faults and the tectonic history of the depressions.The results of this study revealed that the distribution of the faults in the Suhongtu-Dagu depressions in the northern part of the Yin’e Basin varies with region,and the fault system was multi-period,orthotropic,north-east-trending,and north-north-east-trending,with a certain degree of inheritance in terms of the geological setting.Three types of faults were identified:Y-shaped fractures,reverse Y-shaped fractures,and parallel fractures,which can be classified as Paleozoic-Cenozoic continuous syncline faults and intra-depression faults from the top of the Permian to the Upper Cretaceous series and inter-stratigraphic adjustment faults within the Cretaceous System,respectively.The evolution of these faults can be divided into three phases:the controlling faults were the faults that existed before the Early Cretaceous and had been active since then;synclinal faults that formed during the Early Cretaceous;and modified faults that formed since the Early Cretaceous.The development and modification of the coal seams in the Cretaceous Suhongtu Formation in the Hari,Kuanzihu,and Babei sags were strongly controlled and influenced by a multi-phase complex fault system.展开更多
基金funded by the National Natural Science Foundation of China(No.42076069).
文摘The Makran accretionary wedge has the smallest subduction angle among any accretionary prism in the world. The factors controlling the spacing and morphological development of its deep thrust faults, as well as the formation mechanism of shallow normal faults, remain unclear. Meanwhile, the factors affecting the continuity of plane faults must be comprehensively discussed. Clarifying the development characteristics and deformation mechanisms of the Makran accretionary wedge is crucial to effectively guide the exploration of gas hydrate deposits in the area. This study aims to interpret seismic data to identify typical structures in the Makran accretionary wedge, including deep imbricate thrust faults, shallow and small normal faults, wedge-shaped piggyback basins, mud diapirs with fuzzy and disorderly characteristics of reflection, décollements with a northward tilt of 1° – 2°, and large seamounts. Physical simulation-based experiments are performed to comprehensively analyze the results of the plane, section, and slices of the wedge. Results reveal that the distances between and shapes of thrust faults in the deep parts of the Makran accretionary wedge are controlled by the bottom décollement. The uplift of the thrust fault-related folds and the upwelling of the mud diapirs primarily contribute to the formation of small normal faults in the shallow part of the area. The mud diapirs originate from plastic material at the bottom, while those that have developed in the area near the trench are larger. Seamounts and mud diapirs break the continuity of fault plane distribution.
基金granted by the National Science and Technology Major Project of China(Grant No.2017ZX05032-003)the National Key R&D Program of China(Grant No.2017YFC0602202)。
文摘In the Gulf of Mexico and adjacent landmasses,faults are very complex,and their distribution is closely related to plate tectonics,ocean-land boundary,and former structure.The plane position of the faults can be identified by the maximum characteristic of the vertical derivative of the normalized vertical derivative of the total horizontal derivative(NVDR-THDR)of the Bouguer gravity anomaly.The apparent depth of the faults is inverted by the Bouguer gravity anomaly curvature property.Based on tectonic evolutionary processes and the plane distribution and apparent depth characteristics of the faults,a complete fault system for the Gulf of Mexico and adjacent areas has been established,including 102 faults.The apparent depths of 33 first-class faults are 16-20 km and for 69 second-class faults are 12-16 km.The F_(1-2)and F_(1-3)subduction fault zones are two caused by the subduction of the Cocos Plate into the old Yucatan and Chorti landmasses;F_(1-11)and F_(1-12)fault zones extend westward to the coast of Guatemala and do not extend into the continent;F_(1-17)and F_(1-20)faults,which control the boundary of the oceanic crust,do not extend southward into the continent.The fault system,which radiates in a"fan-shaped"structure as a whole,unfolds to the northeast.Faults of different nature and sizes are distributed in the Cocos Plate subduction zone,Continental,Gulf of Mexico,Yucatan old landmass and Caribbean Plate in NW,NNW,NS,NE and NEE directions.In the Gulf of Mexico region,the fault system is a comprehensive reflection of former tectonic movements,such as plate movement,drift of old landmasses and expansion of oceanic crusts.The first-class faults control the plate and ocean-continental boundaries.The second-class faults are subordinate to the first-class faults or related to the distribution of different sedimentary layers.
基金We thank LetPub for its linguistic assistance during the preparation of this manuscript.This work is granted by the National Natural Science Foundation of China(Grant No.42272152)the Major Projects from the Changqing Oilfield of PetroChina(No.ZDZX2021)+2 种基金the Fundamental Research Funds for the Central Universities,CHD(No.300102272205)the Fundamental Research Funds for platform of Liangshan Characteristic Agriculture(015/500827)the Innovation and Entrepreneurship Training Program for University Students,CHD(No.G202210710050).
文摘Research on the characteristics of faults and their evolutionary history since the Cretaceous in the Suhongtu-Dagu depressions can provide a theoretical basis for geological evaluation of the coal seams in the Suhongtu Formation in the northern-central region of the Yin’e Basin.Using 3-D seismic-logging inversion techniques,seismic stratigraphic calibration,stratigraphic sequence delineation,and thickness calculations on the Suhongtu-Dagu depressions were carried out to clarify the planar and profile distributions of the faults,as well as the evolutionary history of these faults and the tectonic history of the depressions.The results of this study revealed that the distribution of the faults in the Suhongtu-Dagu depressions in the northern part of the Yin’e Basin varies with region,and the fault system was multi-period,orthotropic,north-east-trending,and north-north-east-trending,with a certain degree of inheritance in terms of the geological setting.Three types of faults were identified:Y-shaped fractures,reverse Y-shaped fractures,and parallel fractures,which can be classified as Paleozoic-Cenozoic continuous syncline faults and intra-depression faults from the top of the Permian to the Upper Cretaceous series and inter-stratigraphic adjustment faults within the Cretaceous System,respectively.The evolution of these faults can be divided into three phases:the controlling faults were the faults that existed before the Early Cretaceous and had been active since then;synclinal faults that formed during the Early Cretaceous;and modified faults that formed since the Early Cretaceous.The development and modification of the coal seams in the Cretaceous Suhongtu Formation in the Hari,Kuanzihu,and Babei sags were strongly controlled and influenced by a multi-phase complex fault system.
