We quantified the systematic variations in global transform fault morphology,revealing a first-order dependence on the spreading rate.(1)The average age offset of both the full transform and transform sub-segments dec...We quantified the systematic variations in global transform fault morphology,revealing a first-order dependence on the spreading rate.(1)The average age offset of both the full transform and transform sub-segments decrease with increasing spreading rate.(2)The average depth of both the transform valley and adjacent ridges are smaller in the fast compared to the slow systems,reflecting possibly density anomalies associated with warmer mantle at the fast systems and rifting at the slow ridges.However,the average depth difference between the transform valley and adjacent ridges is relatively constant from the fast to slow systems.(3)The nodal basin at a ridge-transform intersection is deeper and dominant at the ultraslow and slow systems,possibly reflecting a lower magma supply and stronger viscous resistance to mantle upwelling near a colder transform wall.In contrast,the nodal high,is most prominent in the fast,intermediate,and hotspot-influenced systems,where robust axial volcanic ridges extend toward the ridge-transform intersection.(4)Statistically,the average transform valley is wider at a transform system of larger age offset,reflecting thicker deforming plates flanking the transform fault.(5)The maximum magnitude of the transform earthquakes increases with age offset owing to an increase in the seismogenic area.Individual transform faults also exhibit significant anomalies owing to the complex local tectonic and magmatic processes.展开更多
Mid-ocean ridge and oceanic transforms are among the most prominent features on the seafloor surface and are crucial for understanding seafloor spreading and plate tectonic dynamics,but the deep structure of the ocean...Mid-ocean ridge and oceanic transforms are among the most prominent features on the seafloor surface and are crucial for understanding seafloor spreading and plate tectonic dynamics,but the deep structure of the oceanic lithosphere remains poorly understood.The large number of microearthquakes occurring along ridges and transforms provide valuable information for gaining an indepth view of the underlying detailed seismic structures,contributing to understanding geodynamic processes within the oceanic lithosphere.Previous studies have indicated that the maximum depth of microseismicity is controlled by the 600-℃isotherm.However,this perspective is being challenged due to increasing observations of deep earthquakes that far exceed this suggested isotherm along mid-ocean ridges and oceanic transform faults.Several mechanisms have been proposed to explain these deep events,and we suggest that local geodynamic processes(e.g.,magma supply,mylonite shear zone,longlived faults,hydrothermal vents,etc.)likely play a more important role than previously thought.展开更多
The transform fault is essentially a displacement fault whose terminal part is adjusted by other tectonic types, its displacement component is absorbed by other structures intersected with it by high angles or meet at...The transform fault is essentially a displacement fault whose terminal part is adjusted by other tectonic types, its displacement component is absorbed by other structures intersected with it by high angles or meet at right angles. The main elements of transform fault are the sleep\|dipping displacement faults and the adjusted structures intersected with it at high angles. According to the combination of tectonic features formed by its two ends of displacement fault and the structures intersected with it, the transform fault can be divided into three types, including the adjusted transform fault of extensional normal fault, the adjusted transform fault of compressive fold and thrust fault, and the compound transform fault. The transform fault is different from the displacement fault, its horizontal displacement may be increased or decreased or not be changed at all as the time of fault movement extended, but for parallel displacement the dislocation will be increased. Therefore, the study of transform fault is very important for the recognition of long time disputed displacement components of huge displacement fault. The traditional Altyn fault is the adjusting fault of the compression deformation of the Western Kunlun and Northern Qilian mountains of the northern margin of the Tibetan Plateau since Cenozoic.展开更多
Large strike-slip faults play a crucial role in regulating the geometry and kinematics of the solid Earth's outer lithospheric plates and the structural deformation of internal continents.They not only control the...Large strike-slip faults play a crucial role in regulating the geometry and kinematics of the solid Earth's outer lithospheric plates and the structural deformation of internal continents.They not only control the geometric structures,motion properties,and direction of the lithospheric plates,but also regulate the complex tectonic stress field and strain state caused by differential motion among multiple blocks within the continent,maintaining the relative stability of the overall stress state of the lithosphere on the Earth's surface.According to the nature and significance of geotectonic structures,strike-slip faults can be divided into interplate types and intraplate tectonic types.Interplate strike-slip faults are transform faults,including oceanic transform faults and continental transform faults.Intraplate strike-slip faults can be divided into continental transfer faults and intraplate transcurrent faults.During the lateral movement of lithospheric plates along the Earth's surface,transform faults adjust the differences in the nature,direction,and rate of movement between different plates.Meanwhile,continental transfer faults and intraplate transcurrent faults adjust the location,nature,style,and differential stress of intraplate tectonic deformation.Strike-slip faults of varying types and scales interact in different ways to maintain the dynamic balance of matter and energy within Earth's lithospheric plates.Based on the concepts,tectonic significance,and recent research advances of strike-slip faults and classical transform faults,this paper summarizes the latest classification of strike-slip faults and their corresponding tectonic implications.It also updates the definitions,geometric characteristics,and kinematic features of oceanic transform faults,continental transform faults,continental transfer faults,and intraplate transcurrent faults.Through typical global examples,this paper comprehensively analyzes the deep structure,structural geometry and kinematic characteristics,evolution process,geological significance,and seismic hazards of different types of strike-slip faults.Furthermore,the frontier science issue and research strategies for the study of oceanic transform faults,continental transfer faults,and intraplate transcurrent faults are summarized as well.展开更多
The oceanic transform fault(OTF)is one of the three types of plate boundaries.It provides an important channel for the exchange of material and energy within the Earth's interior,which is significant for understan...The oceanic transform fault(OTF)is one of the three types of plate boundaries.It provides an important channel for the exchange of material and energy within the Earth's interior,which is significant for understanding global plate tectonics.In recent years,substantial progress has been made in the study of OTFs,including their morphology,crustal accretion mode,stress and strain state,brittle-ductile deformation structures,and segmentation and symmetry of seismicity.The combined effects of magmatism and tectonism shape the morphology and structure of OTF:the spreading rate and the age offsets reflect the thermal structure of the OTF,and thus affect the intensity of magmatism;meanwhile,the stress within the lithosphere and plate motion control the tectonic features and formation of faults.Three-dimensional dynamic models have demonstrated that increased magmatism at mid-ocean ridges destabilizes the fault,thereby facilitating the dynamic evolution of the OTF.Moreover,the maximum depth of earthquakes on OTF is controlled by the thermal structure of the lithosphere,which is crucial for characterizing the frictional properties of faults and understanding their seismic behaviors.Based on recent comprehensive research findings,this paper reviews the tectonic features,three-dimensional morphological structure,and lithospheric thermal structure of OTF,and discusses important scientific issues,including the magmatic-tectonic co-evolution and geodynamic mechanisms of OTF.Future research will combine high-resolution observations and theoretical simulations to further elucidate the processes and mechanisms of OTF,providing important advances to global plate tectonic theory.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
The back propagation (BP)-based artificial neural nets (ANN) can identify complicated relationships among dissolved gas contents in transformer oil and corresponding fault types, using the highly nonlinear mapping nat...The back propagation (BP)-based artificial neural nets (ANN) can identify complicated relationships among dissolved gas contents in transformer oil and corresponding fault types, using the highly nonlinear mapping nature of the neural nets. An efficient BP-ALM (BP with Adaptive Learning Rate and Momentum coefficient) algorithm is proposed to reduce the training time and avoid being trapped into local minima, where the learning rate and the momentum coefficient are altered at iterations. We developed a system of transformer fault diagnosis based on Dissolved Gases Analysis (DGA) with a BP-ALM algorithm. Training patterns were selected from the results of a Refined Three-Ratio method (RTR). Test results show that the system has a better ability of quick learning and global convergence than other methods and a superior performance in fault diagnosis compared to convectional BP-based neural networks and RTR.展开更多
基金The foundation of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0205the National Natural Science Foundation of China under contract Nos 41976064,41890813,41976066,91958211,and 41706056+4 种基金the scholarship of China Scholarship Councilthe foundations of the Chinese Academy of Sciences under contract Nos Y4SL021001,QYZDY-SSW-DQC005,133244KYSB20180029,and 131551KYSB20200021the National Key Research and Development Program of China under contract Nos 2018YFC0309800 and 2018YFC0310105the Foundation of the China Ocean Mineral Resources Research and Development Association under contract No.DY135-S2-1-04the Guangdong Basic and Applied Basic Research Foundation under contract No.2021A1515012227。
文摘We quantified the systematic variations in global transform fault morphology,revealing a first-order dependence on the spreading rate.(1)The average age offset of both the full transform and transform sub-segments decrease with increasing spreading rate.(2)The average depth of both the transform valley and adjacent ridges are smaller in the fast compared to the slow systems,reflecting possibly density anomalies associated with warmer mantle at the fast systems and rifting at the slow ridges.However,the average depth difference between the transform valley and adjacent ridges is relatively constant from the fast to slow systems.(3)The nodal basin at a ridge-transform intersection is deeper and dominant at the ultraslow and slow systems,possibly reflecting a lower magma supply and stronger viscous resistance to mantle upwelling near a colder transform wall.In contrast,the nodal high,is most prominent in the fast,intermediate,and hotspot-influenced systems,where robust axial volcanic ridges extend toward the ridge-transform intersection.(4)Statistically,the average transform valley is wider at a transform system of larger age offset,reflecting thicker deforming plates flanking the transform fault.(5)The maximum magnitude of the transform earthquakes increases with age offset owing to an increase in the seismogenic area.Individual transform faults also exhibit significant anomalies owing to the complex local tectonic and magmatic processes.
基金Supported by the State Key Program of National Natural Science of China(No.42330308)the Project of Donghai Laboratory(No.DH-2022ZY0005)+4 种基金the Scientific Research Fund of the Second Institute of OceanographyMinistry of Natural Resources(No.QHXZ2301)the National Science Foundation for Distinguished Young Scholars of China(No.42025601)for Young Scientists of China(No.41906064)the Zhejiang Provincial Natural Science Foundation of China(No.LDQ24D060001)。
文摘Mid-ocean ridge and oceanic transforms are among the most prominent features on the seafloor surface and are crucial for understanding seafloor spreading and plate tectonic dynamics,but the deep structure of the oceanic lithosphere remains poorly understood.The large number of microearthquakes occurring along ridges and transforms provide valuable information for gaining an indepth view of the underlying detailed seismic structures,contributing to understanding geodynamic processes within the oceanic lithosphere.Previous studies have indicated that the maximum depth of microseismicity is controlled by the 600-℃isotherm.However,this perspective is being challenged due to increasing observations of deep earthquakes that far exceed this suggested isotherm along mid-ocean ridges and oceanic transform faults.Several mechanisms have been proposed to explain these deep events,and we suggest that local geodynamic processes(e.g.,magma supply,mylonite shear zone,longlived faults,hydrothermal vents,etc.)likely play a more important role than previously thought.
基金theNationalNaturalScienceFoundationofChina (No .4 980 2 0 19)
文摘The transform fault is essentially a displacement fault whose terminal part is adjusted by other tectonic types, its displacement component is absorbed by other structures intersected with it by high angles or meet at right angles. The main elements of transform fault are the sleep\|dipping displacement faults and the adjusted structures intersected with it at high angles. According to the combination of tectonic features formed by its two ends of displacement fault and the structures intersected with it, the transform fault can be divided into three types, including the adjusted transform fault of extensional normal fault, the adjusted transform fault of compressive fold and thrust fault, and the compound transform fault. The transform fault is different from the displacement fault, its horizontal displacement may be increased or decreased or not be changed at all as the time of fault movement extended, but for parallel displacement the dislocation will be increased. Therefore, the study of transform fault is very important for the recognition of long time disputed displacement components of huge displacement fault. The traditional Altyn fault is the adjusting fault of the compression deformation of the Western Kunlun and Northern Qilian mountains of the northern margin of the Tibetan Plateau since Cenozoic.
基金supported by the National Natural Science Foundation of China(Grant Nos.42330310,42442012)。
文摘Large strike-slip faults play a crucial role in regulating the geometry and kinematics of the solid Earth's outer lithospheric plates and the structural deformation of internal continents.They not only control the geometric structures,motion properties,and direction of the lithospheric plates,but also regulate the complex tectonic stress field and strain state caused by differential motion among multiple blocks within the continent,maintaining the relative stability of the overall stress state of the lithosphere on the Earth's surface.According to the nature and significance of geotectonic structures,strike-slip faults can be divided into interplate types and intraplate tectonic types.Interplate strike-slip faults are transform faults,including oceanic transform faults and continental transform faults.Intraplate strike-slip faults can be divided into continental transfer faults and intraplate transcurrent faults.During the lateral movement of lithospheric plates along the Earth's surface,transform faults adjust the differences in the nature,direction,and rate of movement between different plates.Meanwhile,continental transfer faults and intraplate transcurrent faults adjust the location,nature,style,and differential stress of intraplate tectonic deformation.Strike-slip faults of varying types and scales interact in different ways to maintain the dynamic balance of matter and energy within Earth's lithospheric plates.Based on the concepts,tectonic significance,and recent research advances of strike-slip faults and classical transform faults,this paper summarizes the latest classification of strike-slip faults and their corresponding tectonic implications.It also updates the definitions,geometric characteristics,and kinematic features of oceanic transform faults,continental transform faults,continental transfer faults,and intraplate transcurrent faults.Through typical global examples,this paper comprehensively analyzes the deep structure,structural geometry and kinematic characteristics,evolution process,geological significance,and seismic hazards of different types of strike-slip faults.Furthermore,the frontier science issue and research strategies for the study of oceanic transform faults,continental transfer faults,and intraplate transcurrent faults are summarized as well.
基金supported by the Natural Science Foundation of Guangdong Province(Grant No.2024B1515020100)the National Natural Science Foundation of China(Grant Nos.42306093,42406071,42306073,42206070)。
文摘The oceanic transform fault(OTF)is one of the three types of plate boundaries.It provides an important channel for the exchange of material and energy within the Earth's interior,which is significant for understanding global plate tectonics.In recent years,substantial progress has been made in the study of OTFs,including their morphology,crustal accretion mode,stress and strain state,brittle-ductile deformation structures,and segmentation and symmetry of seismicity.The combined effects of magmatism and tectonism shape the morphology and structure of OTF:the spreading rate and the age offsets reflect the thermal structure of the OTF,and thus affect the intensity of magmatism;meanwhile,the stress within the lithosphere and plate motion control the tectonic features and formation of faults.Three-dimensional dynamic models have demonstrated that increased magmatism at mid-ocean ridges destabilizes the fault,thereby facilitating the dynamic evolution of the OTF.Moreover,the maximum depth of earthquakes on OTF is controlled by the thermal structure of the lithosphere,which is crucial for characterizing the frictional properties of faults and understanding their seismic behaviors.Based on recent comprehensive research findings,this paper reviews the tectonic features,three-dimensional morphological structure,and lithospheric thermal structure of OTF,and discusses important scientific issues,including the magmatic-tectonic co-evolution and geodynamic mechanisms of OTF.Future research will combine high-resolution observations and theoretical simulations to further elucidate the processes and mechanisms of OTF,providing important advances to global plate tectonic theory.
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.
文摘The back propagation (BP)-based artificial neural nets (ANN) can identify complicated relationships among dissolved gas contents in transformer oil and corresponding fault types, using the highly nonlinear mapping nature of the neural nets. An efficient BP-ALM (BP with Adaptive Learning Rate and Momentum coefficient) algorithm is proposed to reduce the training time and avoid being trapped into local minima, where the learning rate and the momentum coefficient are altered at iterations. We developed a system of transformer fault diagnosis based on Dissolved Gases Analysis (DGA) with a BP-ALM algorithm. Training patterns were selected from the results of a Refined Three-Ratio method (RTR). Test results show that the system has a better ability of quick learning and global convergence than other methods and a superior performance in fault diagnosis compared to convectional BP-based neural networks and RTR.
