The important event in Jurassic tectonics in Mongolia was the subduction and closure of the Mongolia-Okhotsk ocean;correspondingly,basin evolution can be divided into two main stages,related to the orogeny and collaps...The important event in Jurassic tectonics in Mongolia was the subduction and closure of the Mongolia-Okhotsk ocean;correspondingly,basin evolution can be divided into two main stages,related to the orogeny and collapse of the orogenic belt,respectively.The developing of Early-Middle Jurassic basins to the north of the ocean resulted from back-arc extension.The fossil sutures,from the China-SE Asia sub-continent to the south of the ocean,were rejuvenated by subduction-related orogeny;in addition,the Yanshanian intra-continental movement occurred.Three Early-Middle Jurassic molasse basins were developed by movement in Inner Mongolia,all of which stretched westwards (or northwards) into Mongolia;therefore,the molasse basins in eastern and southern Mongolia had the same geometric and kinematic features as the basins in the Inner Mongolia.Owing to the collapse of the MongoliaOkhotsk orogenic belt,a group of rift basins developed during the Late Jurassic.In eastern Mongolia,the NE orientated extensional basins were controlled by the neogenic NE-structure.The contemporary basins in southern Mongolia and the neighboring areas in China were constrained by remobilization (inherited activation) of the latitudinal or ENE-directional basement structures.Three stages can be recognized in the evolution of the Early-Middle Jurassic basins after reversal;the basins also experienced four episodes of reformation.展开更多
The existing genetic models of the South China Sea(SCS)include an extrusion model of the Indochina Peninsula,a back-arc extension model,and a subduction and dragging model of the Proto-South China Sea(PSCS).However,no...The existing genetic models of the South China Sea(SCS)include an extrusion model of the Indochina Peninsula,a back-arc extension model,and a subduction and dragging model of the Proto-South China Sea(PSCS).However,none of these models has been universally accepted because they do not fully match a large number of geological phenomena and facts.By examining the regional tectonics and integrating them with measured data for the SCS,in this study,a back-arc spreading-sinistral shear model is proposed.It is suggested that the SCS is a back-arc basin formed by northward subduction of the PSCS and its formation was triggered by left-lateral strike-slip motion due to the northward drift of the Philippine Sea Plate.The left-lateral strike-slip fault on the western margin caused by the Indo-Eurasian collision changed the direction of the Southwest Sub-basin's spreading axis from nearly E–W to NE–SW,and subduction retreat caused the spreading ridge to jump southward.This study summarizes the evolution of the SCS and adjacent regions since the Late Mesozoic.展开更多
The marginal sea and back-arc basins in the Western Pacific Ocean have become the focus of tectonics due to their unique tectonic location.To understand the deep crustal structure in the back-arc region,we present a 5...The marginal sea and back-arc basins in the Western Pacific Ocean have become the focus of tectonics due to their unique tectonic location.To understand the deep crustal structure in the back-arc region,we present a 545-kmlong active-source ocean bottom seismometer(OBS)wide-angle reflection/refraction profile in the East China Sea.The P wave velocity model shows that the Moho depth rises significantly,from approximately 30 km in the East China Sea shelf to approximately 16 km in the axis of the Okinawa Trough.The lower crustal high-velocity zone(HVZ)in the southern Okinawa Trough,with V_(p) of 6.8-7.3 km/s,is a remarkable manifestation of the mantle material upwelling and accretion to the lower crust.This confirms that the lower crustal high-velocity mantle accretion is developed in the southern Okinawa Trough.During the process of back-arc extension,the crustal structure of the southern Okinawa Trough is completely invaded and penetrated by the upper mantle material in the axis region.In some areas of the southern central graben,the crust may has broken up and entered the initial stage of seafloor spreading.The discontinuous HVZs in the lower crust in the back-arc region also indicate the migration of spreading centers in the back-arc region since the Cenozoic.The asthenosphere material upwelling in the continent-ocean transition zone is constantly driving the lithosphere eastward for episodic extension,and is causing evident tectonic migration in the Western Pacific back-arc region.展开更多
文摘The important event in Jurassic tectonics in Mongolia was the subduction and closure of the Mongolia-Okhotsk ocean;correspondingly,basin evolution can be divided into two main stages,related to the orogeny and collapse of the orogenic belt,respectively.The developing of Early-Middle Jurassic basins to the north of the ocean resulted from back-arc extension.The fossil sutures,from the China-SE Asia sub-continent to the south of the ocean,were rejuvenated by subduction-related orogeny;in addition,the Yanshanian intra-continental movement occurred.Three Early-Middle Jurassic molasse basins were developed by movement in Inner Mongolia,all of which stretched westwards (or northwards) into Mongolia;therefore,the molasse basins in eastern and southern Mongolia had the same geometric and kinematic features as the basins in the Inner Mongolia.Owing to the collapse of the MongoliaOkhotsk orogenic belt,a group of rift basins developed during the Late Jurassic.In eastern Mongolia,the NE orientated extensional basins were controlled by the neogenic NE-structure.The contemporary basins in southern Mongolia and the neighboring areas in China were constrained by remobilization (inherited activation) of the latitudinal or ENE-directional basement structures.Three stages can be recognized in the evolution of the Early-Middle Jurassic basins after reversal;the basins also experienced four episodes of reformation.
基金funded by the projects of the China Geological Survey(DD20160138,GZH201300502,DD20190378)the Major Special Project for talent team introduction of the Southern Marine Science and Engineering Guang Dong Laboratory(Guang Zhou)(GML2019ZD0207)。
文摘The existing genetic models of the South China Sea(SCS)include an extrusion model of the Indochina Peninsula,a back-arc extension model,and a subduction and dragging model of the Proto-South China Sea(PSCS).However,none of these models has been universally accepted because they do not fully match a large number of geological phenomena and facts.By examining the regional tectonics and integrating them with measured data for the SCS,in this study,a back-arc spreading-sinistral shear model is proposed.It is suggested that the SCS is a back-arc basin formed by northward subduction of the PSCS and its formation was triggered by left-lateral strike-slip motion due to the northward drift of the Philippine Sea Plate.The left-lateral strike-slip fault on the western margin caused by the Indo-Eurasian collision changed the direction of the Southwest Sub-basin's spreading axis from nearly E–W to NE–SW,and subduction retreat caused the spreading ridge to jump southward.This study summarizes the evolution of the SCS and adjacent regions since the Late Mesozoic.
基金supported by the National Key Basic Research Program of China(Grant No.2013CB429701)the National Natural Science Foundation of China(Grant Nos.41606083,91958210,41606050 and 41210005)+1 种基金AoShan Technological Innovation Projects of National Laboratory for Marine Science and Technology(Qingdao)(2015ASKJ03)National Marine Geological Special Project(DD20190236,DD20190365,DD20190377)。
文摘The marginal sea and back-arc basins in the Western Pacific Ocean have become the focus of tectonics due to their unique tectonic location.To understand the deep crustal structure in the back-arc region,we present a 545-kmlong active-source ocean bottom seismometer(OBS)wide-angle reflection/refraction profile in the East China Sea.The P wave velocity model shows that the Moho depth rises significantly,from approximately 30 km in the East China Sea shelf to approximately 16 km in the axis of the Okinawa Trough.The lower crustal high-velocity zone(HVZ)in the southern Okinawa Trough,with V_(p) of 6.8-7.3 km/s,is a remarkable manifestation of the mantle material upwelling and accretion to the lower crust.This confirms that the lower crustal high-velocity mantle accretion is developed in the southern Okinawa Trough.During the process of back-arc extension,the crustal structure of the southern Okinawa Trough is completely invaded and penetrated by the upper mantle material in the axis region.In some areas of the southern central graben,the crust may has broken up and entered the initial stage of seafloor spreading.The discontinuous HVZs in the lower crust in the back-arc region also indicate the migration of spreading centers in the back-arc region since the Cenozoic.The asthenosphere material upwelling in the continent-ocean transition zone is constantly driving the lithosphere eastward for episodic extension,and is causing evident tectonic migration in the Western Pacific back-arc region.
