By means of inversion of fault slip data, the parameters of 20 tectonic stress tensors in Southwest Yunnan region are determined. Compared with the average stress field of the region obtained from focal mechanism solu...By means of inversion of fault slip data, the parameters of 20 tectonic stress tensors in Southwest Yunnan region are determined. Compared with the average stress field of the region obtained from focal mechanism solutions, the following characteristics of modern tectonic stress field in this region are obtained. From the west of Zhenyuan-Yingpanshan fault to the south of Longling fault zone, the maximum compressional stress is in NNE direction and the stress regime is mainly of strike-slip type. In Longling fault zone and the area north to it, the direction of maximum compressional stress is near-NS or NNW, the stress regime is of strike-slip type.展开更多
Hydrothermal vent incidence was once thought to be proportional to the spreading rate of the mid-ocean ridges(MORs).However,more and more studies have shown that the ultraslow-spreading ridges(e.g.,Southwest Indian Ri...Hydrothermal vent incidence was once thought to be proportional to the spreading rate of the mid-ocean ridges(MORs).However,more and more studies have shown that the ultraslow-spreading ridges(e.g.,Southwest Indian Ridge(SWIR))have a relatively higher incidence of hydrothermal venting fields.The Qiaoyue Seamount(52.1°E)is located at the southern side of segment#25 of the SWIR,to the west of the Gallieni transform fault.The Chinese Dayang cruises conducted eight preliminary deep-towed surveys of hydrothermal activity in the area during 2009 and 2018.Here,through comprehensive analyses of the video and photos obtained by the deep-towed platforms,rock samples,and water column turbidity anomalies,a high-temperature,ultramafic-hosted hydrothermal system is predicted on the northern flank of the Qiaoyue Seamount.We propose that this hydrothermal system is most likely to be driven by gabboric intrusions.Efficient hydrothermal circulation channels appear against a backdrop of high rock permeability related to the detachment fault.展开更多
Based on the orthotropic elastic theory of rock masses, the X-ray method was used to measure the distribution of macro-residual strain energy density along a depth profile,using core samples taken from 47 large-apertu...Based on the orthotropic elastic theory of rock masses, the X-ray method was used to measure the distribution of macro-residual strain energy density along a depth profile,using core samples taken from 47 large-aperture deep boreholes in four regions of Southwest China： the Longmenshan, Anninghe, Honghe, and Xianshuihe fault zones.Then, the vertical gradients of the macro-residual strain energy density and the macroresidual strain energy contained in high-energy cuboid block segments along each fault zone were determined. The results demonstrate that the macro-residual strain energy stored at shallow levels in the rock mass in these fault zones may be partly responsible for generating many large earthquakes and may explain why the large earthquakes in this region are typically shallow.展开更多
Field investigation has revealed that the large-scale dextral strike-slip movement and the associated tectonic deformation along the Red River fault zone have the following features: geometrically, the Red River fault...Field investigation has revealed that the large-scale dextral strike-slip movement and the associated tectonic deformation along the Red River fault zone have the following features: geometrically, the Red River fault zone can be divided into three deformation regions, namely, the north, central and south regions. The north region lies on the eastern side of the Northwest Yunnan extensional taphrogenic belt, which is characterized by the 3 sets of rift-depression basins striking NNW, NNE and near N-S since the Pliocene time, and on its western side is the Lanping-Yunlong compressive deformation belt of the Paleogene to Neogene; the deformation in the central region is characterized by dextral strike-slip or shearing. The east Yunnan Miocene compressive deformation belt lies on the eastern side of the fault in the south, and the Tengtiaohe tensile fault depression belt is located on its west. In terms of tectonic geomorphology, the aforementioned deformation is represented by basin-range tectonics in the north, linear faulted valley-basins in the central part and compressive (or tensional) basins in the south. Among them, the great variance in elevation of the planation surfaces on both sides of the Cangshan-Erhai fault suggests prominent normal faulting along the Red River fault since the Pliocene. From the viewpoint of spatial-temporal evolution, the main active portion of the fault was the southern segment in the Paleogene-Miocene-Pliocene, which is represented by “tearing” from south to north. The main active portion of the fault has migrated to the northern segment since the Pliocene, especially in the late Quaternary, which is characterized by extensional slip from north to southeast. The size of the deformation region and the magnitude of deformation show that the eastern plate of the Red River fault has been an active plate of the relative movement of blocks.展开更多
基金Chinese Joint Seismological Science Foundation (9507424).Contribution No. 2001A001, Institute of Crustal Dynamics, China Seism
文摘By means of inversion of fault slip data, the parameters of 20 tectonic stress tensors in Southwest Yunnan region are determined. Compared with the average stress field of the region obtained from focal mechanism solutions, the following characteristics of modern tectonic stress field in this region are obtained. From the west of Zhenyuan-Yingpanshan fault to the south of Longling fault zone, the maximum compressional stress is in NNE direction and the stress regime is mainly of strike-slip type. In Longling fault zone and the area north to it, the direction of maximum compressional stress is near-NS or NNW, the stress regime is of strike-slip type.
基金The National Key Research and Development Program of China under contract No.2016YFC0304905the National Natural Science Foundation of China under contract No.41806076+1 种基金the Scientific Research Fund of the Second Institute of Oceanography,MNR under contract No.JG1804the China Ocean Mineral Resources R&D Association(COMRA)Major Project under contract Nos DY135-S1-1-01,DY135-S1-1-02 and DY135-S1-1-09。
文摘Hydrothermal vent incidence was once thought to be proportional to the spreading rate of the mid-ocean ridges(MORs).However,more and more studies have shown that the ultraslow-spreading ridges(e.g.,Southwest Indian Ridge(SWIR))have a relatively higher incidence of hydrothermal venting fields.The Qiaoyue Seamount(52.1°E)is located at the southern side of segment#25 of the SWIR,to the west of the Gallieni transform fault.The Chinese Dayang cruises conducted eight preliminary deep-towed surveys of hydrothermal activity in the area during 2009 and 2018.Here,through comprehensive analyses of the video and photos obtained by the deep-towed platforms,rock samples,and water column turbidity anomalies,a high-temperature,ultramafic-hosted hydrothermal system is predicted on the northern flank of the Qiaoyue Seamount.We propose that this hydrothermal system is most likely to be driven by gabboric intrusions.Efficient hydrothermal circulation channels appear against a backdrop of high rock permeability related to the detachment fault.
基金supported by the Joint Seismology Science Foundation(85012,850708,863017,88138,91046)Old Professor Science Foundation(201041)
文摘Based on the orthotropic elastic theory of rock masses, the X-ray method was used to measure the distribution of macro-residual strain energy density along a depth profile,using core samples taken from 47 large-aperture deep boreholes in four regions of Southwest China： the Longmenshan, Anninghe, Honghe, and Xianshuihe fault zones.Then, the vertical gradients of the macro-residual strain energy density and the macroresidual strain energy contained in high-energy cuboid block segments along each fault zone were determined. The results demonstrate that the macro-residual strain energy stored at shallow levels in the rock mass in these fault zones may be partly responsible for generating many large earthquakes and may explain why the large earthquakes in this region are typically shallow.
文摘Field investigation has revealed that the large-scale dextral strike-slip movement and the associated tectonic deformation along the Red River fault zone have the following features: geometrically, the Red River fault zone can be divided into three deformation regions, namely, the north, central and south regions. The north region lies on the eastern side of the Northwest Yunnan extensional taphrogenic belt, which is characterized by the 3 sets of rift-depression basins striking NNW, NNE and near N-S since the Pliocene time, and on its western side is the Lanping-Yunlong compressive deformation belt of the Paleogene to Neogene; the deformation in the central region is characterized by dextral strike-slip or shearing. The east Yunnan Miocene compressive deformation belt lies on the eastern side of the fault in the south, and the Tengtiaohe tensile fault depression belt is located on its west. In terms of tectonic geomorphology, the aforementioned deformation is represented by basin-range tectonics in the north, linear faulted valley-basins in the central part and compressive (or tensional) basins in the south. Among them, the great variance in elevation of the planation surfaces on both sides of the Cangshan-Erhai fault suggests prominent normal faulting along the Red River fault since the Pliocene. From the viewpoint of spatial-temporal evolution, the main active portion of the fault was the southern segment in the Paleogene-Miocene-Pliocene, which is represented by “tearing” from south to north. The main active portion of the fault has migrated to the northern segment since the Pliocene, especially in the late Quaternary, which is characterized by extensional slip from north to southeast. The size of the deformation region and the magnitude of deformation show that the eastern plate of the Red River fault has been an active plate of the relative movement of blocks.
