The Laji Shan—Jishi Shan tectonic belt(LJTB),located in the southern part of the northeastern Tibetan Plateau(NETP),is a tectonic window to reveal regional tectonic deformation in the NETP.However,its kinematics in t...The Laji Shan—Jishi Shan tectonic belt(LJTB),located in the southern part of the northeastern Tibetan Plateau(NETP),is a tectonic window to reveal regional tectonic deformation in the NETP.However,its kinematics in the Holocene remains controversial.We obtain the latest and dense horizontal velocity field based on data collected from our newly constructed and existing GNSS stations.Combined with fault kinematics from geologic observations,we analyze the crustal deformation characteristics along the LJTB.The results show that:(1)The Laji Shan fault(LJF)is inactive,and the northwest-oriented Jishi Shan fault(JSF)exhibits a significant dextral and thrust slip.(2)The transpression along the arc-shaped LJTB accommodates deformation transformation between the dextral Riyue Shan fault and the sinistral west Qinling fault.(3)With the continuous pushing of the Indian plate,internal strains in the Tibetan Plateau are continuously transferred in the northeast via the LJTB as they are gradually dissipated near the LJTB and translated into significant crustal uplift in these regions.展开更多
There are lots of achievements about kinematics of Chinese mainland and its vicinity determined from historic earthquake data, Quaternary fault rates and geodesy observations, which provide basic data for analysis of ...There are lots of achievements about kinematics of Chinese mainland and its vicinity determined from historic earthquake data, Quaternary fault rates and geodesy observations, which provide basic data for analysis of seismic hazard in study areas. Based on impreciseness in using energy of 47 earthquakes with magnitude greater than 7.0 in previous study, we firstly collected source parameters, surface ruptures and displacements of major earthquakes carefully, and divided them into small segmentations with these data gathered. Secondly, we determined contemporary deformation field from latest earthquake mechanisms, Quaternary fault slip rates and geodesy observations. Finally, we evaluated moment deficit of study areas from historic earthquake data and predicted deformation field, and removed 10 percent of aseismic deformation. Combining with previous results, we analyzed the seismic hazard of study areas. The results show that there are some areas with large moment deficit in Chinese mainland. There are also large moment deficit areas, including regions around the Ordos Block, southeastern coast of China and the Bakal rift zone. Previous studies show that there may be some potential earthquakes in the near future in Darts of areas mentioned above.展开更多
As a crucial segment of the oblique Indian-Eurasian convergence zone,the southeast(SE)Tibetan Plateau exhibits intricate crustal deformation and frequent seismic activity.The complex lithospheric deformation character...As a crucial segment of the oblique Indian-Eurasian convergence zone,the southeast(SE)Tibetan Plateau exhibits intricate crustal deformation and frequent seismic activity.The complex lithospheric deformation characteristics and associated dynamic mechanisms have been subjects of intense debate.By integrating geophysical data,active tectonics,and geodetic observations,we analyze the lithospheric deformation features and geodynamic processes in SE Tibetan Plateau.Our analysis reveals that the upper crust in SE Tibetan Plateau undergoes clockwise rotation around the Eastern Himalayan syntaxis,indicating distributed deformation between the Sagaing and Xianshuihe-Xiaojiang faults.In the lower crust,deformation direction significantly differs from striking of surface structures.Approximately bounded by 26°N,the seismic anisotropy observations in the northern part of the study area mainly originates from the crust,while that in the southern part stems from the asthenospheric mantle.Additionally,significant variations in crustal and lithospheric thickness and topography are observed along this boundary.The northern region features a crustal thickness of 60–70 km,lithospheric thickness of 140–180 km,and average elevations exceeding 4000 m,whereas the southern region shows a crustal thickness of about 30 km,lithospheric thickness of 80–100 km,and average elevations decreasing to 2000 m.The lithosphere in SE Tibetan Plateau is mechanically weak,characterized by a thin equivalent elastic thickness.Seismogenic layers are present in both the crust and upper mantle.The existence of two middle-to-lower crustal weak zones suggests potential material flow over geological timescales driven by gravitational(topography)variations.We argue that complex lithospheric deformation in SE Tibetan Plateau results from multiple geodynamic processes.North of approximately 26°N,lithospheric deformation can be attributed to gravitational collapse and induced middle-to-lower crustal flow,and extrusion of upper crustal blocks.South of this boundary,in addition to block extrusion and gravitational collapse,tractions from mantle flow may dominate,possibly influenced by the retreat/rollback of the Burma and Sunda plates or mantle upwelling from the Hainan mantle plume.展开更多
The SE Tibetan Plateau,tectonically situated in the eastern India-Eurasia oblique convergence zone,has experienced multiple stages of deformation since the Cenozoic.Three major tectonic boundaries—the Ailaoshan-Red R...The SE Tibetan Plateau,tectonically situated in the eastern India-Eurasia oblique convergence zone,has experienced multiple stages of deformation since the Cenozoic.Three major tectonic boundaries—the Ailaoshan-Red River,ChongshanLincang-Inthanon,and Gaoligong-Mogok shear zones—delineate the first-order tectonic framework in this region.The most striking structural features in the block interiors are a series of NW-and NE-trending fault systems,such as the Dayingjiang,Longlin-Ruili,Nantinghe,Red River,Weixi-Qiaohou,and Lancang-Genma faults,which have conjugate geometric relationships.In this study,we review these structures’geometric and kinematic characteristics and deformation histories.A synthesis of existing geological observations,geomorphological analyses,and chronological data reveals three major Cenozoic tectonothermal events,including crustal shortening,strike-slip shearing,and kinematic reversal.The boundary structures controlled the tectonic extrusion of plateau material during the early Oligocene-early Miocene.In the mid-late Miocene,NW-and NE-trending fault systems mostly experienced diachronous slip-sense inversions.The onset and spatial trend of regional kinematic reversal are constrained by existing chronologic data.Together with geophysical and geodetic observations,the activity and geodynamic drivers of the major fault systems and regional deformation styles are explored,revealing that the SE Tibetan Plateau underwent a transition from discrete(lateral block extrusion)to diffuse deformation in the mid-late Miocene.The intracontinental crustal deformation and its coupling with dynamic processes at depth during the plateau growth are discussed in the context of the IndiaEurasia convergence.展开更多
基金supported by the National Science Foundation of China(41874117)the Second Tibetan Plateau Scientific Expedition and Research Program(SETP)(2019QZKK0901)Natural Science Basic Research Program of Shaanxi(Program No.2023-JC-ON-0309)。
文摘The Laji Shan—Jishi Shan tectonic belt(LJTB),located in the southern part of the northeastern Tibetan Plateau(NETP),is a tectonic window to reveal regional tectonic deformation in the NETP.However,its kinematics in the Holocene remains controversial.We obtain the latest and dense horizontal velocity field based on data collected from our newly constructed and existing GNSS stations.Combined with fault kinematics from geologic observations,we analyze the crustal deformation characteristics along the LJTB.The results show that:(1)The Laji Shan fault(LJF)is inactive,and the northwest-oriented Jishi Shan fault(JSF)exhibits a significant dextral and thrust slip.(2)The transpression along the arc-shaped LJTB accommodates deformation transformation between the dextral Riyue Shan fault and the sinistral west Qinling fault.(3)With the continuous pushing of the Indian plate,internal strains in the Tibetan Plateau are continuously transferred in the northeast via the LJTB as they are gradually dissipated near the LJTB and translated into significant crustal uplift in these regions.
基金sponsored by the monitoring,prediction and studying foundation of China Earthquake Administration(163403)
文摘There are lots of achievements about kinematics of Chinese mainland and its vicinity determined from historic earthquake data, Quaternary fault rates and geodesy observations, which provide basic data for analysis of seismic hazard in study areas. Based on impreciseness in using energy of 47 earthquakes with magnitude greater than 7.0 in previous study, we firstly collected source parameters, surface ruptures and displacements of major earthquakes carefully, and divided them into small segmentations with these data gathered. Secondly, we determined contemporary deformation field from latest earthquake mechanisms, Quaternary fault slip rates and geodesy observations. Finally, we evaluated moment deficit of study areas from historic earthquake data and predicted deformation field, and removed 10 percent of aseismic deformation. Combining with previous results, we analyzed the seismic hazard of study areas. The results show that there are some areas with large moment deficit in Chinese mainland. There are also large moment deficit areas, including regions around the Ordos Block, southeastern coast of China and the Bakal rift zone. Previous studies show that there may be some potential earthquakes in the near future in Darts of areas mentioned above.
基金jointly supported by the National Key Research and Development Program of China(Grant No.2023YFC3007301)the National Natural Science Foundation of China(Grant Nos.U2344212,42372249,42272247)the National Postdoctoral Researcher Funding Program(Grant No.GZC20230043)。
文摘As a crucial segment of the oblique Indian-Eurasian convergence zone,the southeast(SE)Tibetan Plateau exhibits intricate crustal deformation and frequent seismic activity.The complex lithospheric deformation characteristics and associated dynamic mechanisms have been subjects of intense debate.By integrating geophysical data,active tectonics,and geodetic observations,we analyze the lithospheric deformation features and geodynamic processes in SE Tibetan Plateau.Our analysis reveals that the upper crust in SE Tibetan Plateau undergoes clockwise rotation around the Eastern Himalayan syntaxis,indicating distributed deformation between the Sagaing and Xianshuihe-Xiaojiang faults.In the lower crust,deformation direction significantly differs from striking of surface structures.Approximately bounded by 26°N,the seismic anisotropy observations in the northern part of the study area mainly originates from the crust,while that in the southern part stems from the asthenospheric mantle.Additionally,significant variations in crustal and lithospheric thickness and topography are observed along this boundary.The northern region features a crustal thickness of 60–70 km,lithospheric thickness of 140–180 km,and average elevations exceeding 4000 m,whereas the southern region shows a crustal thickness of about 30 km,lithospheric thickness of 80–100 km,and average elevations decreasing to 2000 m.The lithosphere in SE Tibetan Plateau is mechanically weak,characterized by a thin equivalent elastic thickness.Seismogenic layers are present in both the crust and upper mantle.The existence of two middle-to-lower crustal weak zones suggests potential material flow over geological timescales driven by gravitational(topography)variations.We argue that complex lithospheric deformation in SE Tibetan Plateau results from multiple geodynamic processes.North of approximately 26°N,lithospheric deformation can be attributed to gravitational collapse and induced middle-to-lower crustal flow,and extrusion of upper crustal blocks.South of this boundary,in addition to block extrusion and gravitational collapse,tractions from mantle flow may dominate,possibly influenced by the retreat/rollback of the Burma and Sunda plates or mantle upwelling from the Hainan mantle plume.
基金supported by the Natural Science Foundation of Guangdong Province(Grant Nos.2021A1515011631,202102020490 and 2019B1515120019)the National Natural Science Foundation of China(Grant Nos.U1701641 and41802213)+1 种基金the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,Grant No.2019QZKK0703)Guangdong Province Introduced Innovative and R&D Team of Geological Processes and Natural Disasters around the South China Sea(Grant No.2016ZT06N331)。
文摘The SE Tibetan Plateau,tectonically situated in the eastern India-Eurasia oblique convergence zone,has experienced multiple stages of deformation since the Cenozoic.Three major tectonic boundaries—the Ailaoshan-Red River,ChongshanLincang-Inthanon,and Gaoligong-Mogok shear zones—delineate the first-order tectonic framework in this region.The most striking structural features in the block interiors are a series of NW-and NE-trending fault systems,such as the Dayingjiang,Longlin-Ruili,Nantinghe,Red River,Weixi-Qiaohou,and Lancang-Genma faults,which have conjugate geometric relationships.In this study,we review these structures’geometric and kinematic characteristics and deformation histories.A synthesis of existing geological observations,geomorphological analyses,and chronological data reveals three major Cenozoic tectonothermal events,including crustal shortening,strike-slip shearing,and kinematic reversal.The boundary structures controlled the tectonic extrusion of plateau material during the early Oligocene-early Miocene.In the mid-late Miocene,NW-and NE-trending fault systems mostly experienced diachronous slip-sense inversions.The onset and spatial trend of regional kinematic reversal are constrained by existing chronologic data.Together with geophysical and geodetic observations,the activity and geodynamic drivers of the major fault systems and regional deformation styles are explored,revealing that the SE Tibetan Plateau underwent a transition from discrete(lateral block extrusion)to diffuse deformation in the mid-late Miocene.The intracontinental crustal deformation and its coupling with dynamic processes at depth during the plateau growth are discussed in the context of the IndiaEurasia convergence.
