A large number of basic dikes, which indicate an important tectonic-magmatic event in the eastern part of the Central Qilian （祁连） orogenic belt, were found from Maxianshan （马衔山） rock group, Yongjing （永靖） ...A large number of basic dikes, which indicate an important tectonic-magmatic event in the eastern part of the Central Qilian （祁连） orogenic belt, were found from Maxianshan （马衔山） rock group, Yongjing （永靖） county, Gansu （甘肃） Province, China. According to the research on the characteristics of geology and petrology, the basic dike swarms, widely intruded in Maxianshan rock group, are divided into two phases by the authors. U-Pb isotope of zircons from the basic dikes above two phases is separately determined by LA-ICP-MS in the Key Laboratory of Continental Dynamics of Northwest University, China and the causes of formation of the zircons are studied using CL images. The formation age of the earlier phase of metagabbro dikes is （441.1±1.4） Ma （corresponding to the early stage of Early Silurian）, and the age of the main metamorphic period is （414.3±1.2） Ma （corresponding to the early stage of Early Devonian）. The formation age of the later phase of diabase dike swarms is （434±1.0） Ma （corresponding to the late stage of Early Silurian）. The cap- tured-zircons from diabase dike swarms saved some information of material interfusion by Maxianshan rock group （^207pb/206pb apparent ages are （2 325±3）-（2 573 ±6） Ma）, and some zircons from diabase dike swarms also saved impacted information by tectonic thermal event during the late period of Caledonian movement （^206pb/^238U apparent ages are （400±2）-（429±2） Ma）. By combining the results of the related studies, the basic dikes within Maxianshan rock group were considered to be formed in the transfer period, from subductional orogeny towards collisional orogeny, which represents geological records of NW-SE extension during regional NE-SW towards intense compression in the Central Qilian block.展开更多
The Sr, Nd and Pb isotopic characteristics of the Wudang basic dyke swarms and basic volcanics of the Yaolinghe Group show that they were derived from the same multi\|component mixing source in the mantle. The Wudang ...The Sr, Nd and Pb isotopic characteristics of the Wudang basic dyke swarms and basic volcanics of the Yaolinghe Group show that they were derived from the same multi\|component mixing source in the mantle. The Wudang basic dyke swarms have (\{\}\+\{87\}Sr/\{\}\+\{86\}Sr)\-i=\{0.6905\}～\{0.7061\}, ε\-\{Nd\}(t)=\{-1.9\}～\{5.0\}, Δ\{\}\+\{208\}Pb/\+\{204\}Pb=\{35.49\}～\{190.26\}, Δ\{\}\+\{207\}Pb/\{\}\+\{204\}Pb=4～85, low Th/Ta and a wide range of La/Yb ratios; and the basic volcanics of the Yaolinghe Group have (\{\}\+\{87\}Sr/\{\}\+\{86\}Sr)\-i=\{0.6487\}～\{0.7075\}, ε\-\{Nd\}(t)=\{0.11\}～\{3.94\}, Δ\{\}\+\{208\}Pb/\{\}\+\{204\}Pb=\{-81.58\}～\{219.95\}, Δ\{\}\+\{207\}Pb/\{\}\+\{204\}Pb=\{4.44\}～\{16.68\} and higher Th/Ta and La/Yb ratios, indicating that their source is a mixture of DM and EMII, and the basic volcanics of the Yaolinghe Group were contaminated by crust materials en rout to the surface. Based on the geochemical features of continental tholeiitic basalts and being products of different facies derived from the same source, it can be concluded that an important rifting event in the South Qinling basement block occurred during Neoproterozoic, followed by a setting of oceanic basin in the Early Paleozoic.展开更多
Introduction 2013 saw the sixth anniversary of the formulation of Regulations of the People＇s Republic of China on Disclosure of Government Information （hereinafter referred to as the Regulations） and the fifth ann...Introduction 2013 saw the sixth anniversary of the formulation of Regulations of the People＇s Republic of China on Disclosure of Government Information （hereinafter referred to as the Regulations） and the fifth anniversary of their being put into effect. As the Regulations were stipulated and put into force,展开更多
Recent geological study and survey on the scale of 1: 50000 in northern Guangxi have made some advancements: meta-basic-ultrabasic rocks which occured as bedding injection sheets in the Sanrnenjie formation of the Pro...Recent geological study and survey on the scale of 1: 50000 in northern Guangxi have made some advancements: meta-basic-ultrabasic rocks which occured as bedding injection sheets in the Sanrnenjie formation of the Proterozoic Danzhou group and caused contact metamorphism or hydrothermal alteration in adjacent wallrocks, were originated in extensional environment. Basic rocks belong to deep-sea tholeiite. TLe meta-basic -ultrabasic rocks sufferred intense deformation partitioning, resulting in lenticular network which was composed of mylonite zones in highly de formed field and lensoids in less- or non-deformed field. This structural pattern was explained as "melange" or "non-rooted cool intrusion " by previous workers. The deformation partitioning was mainly pure shearing in the early stage plus simple shearing in the later stage. This evolution was closely related to progressive deformation of the Guangxi orogeny.展开更多
Wave ray theory is employed to study features of propagation pathways（rays） of vortex Rossby waves in typhoons with asymmetric basic flow, where the tangential asymmetric basic flow is constructed by superimposing t...Wave ray theory is employed to study features of propagation pathways（rays） of vortex Rossby waves in typhoons with asymmetric basic flow, where the tangential asymmetric basic flow is constructed by superimposing the wavenumber-1 perturbation flow on the symmetric basic flow, and the radial basic flow is derived from the non-divergence equation. Results show that, in a certain distance, the influences of the asymmetry in the basic flow on group velocities and slopes of rays of vortex Rossby waves are mainly concentrated near the radius of maximum wind（RMW）, whereas it decreases outside the RMW. The distributions of radial and tangential group velocities of the vortex Rossby waves in the asymmetric basic flow are closely related to the azimuth location of the maximum speed of the asymmetric basic flow, and the importance of radial and tangential basic flow on the group velocities would change with radius. In addition, the stronger asymmetry in the basic flow always corresponds to faster outward energy propagation of vortex Rossby waves. In short, the group velocities, and thereby the wave energy propagation and vortex Rossby wave ray slope in typhoons, would be changed by the asymmetry of the basic flow.展开更多
基金This paper is supported by the China Geological Survey (No. 1212010510416)
文摘A large number of basic dikes, which indicate an important tectonic-magmatic event in the eastern part of the Central Qilian （祁连） orogenic belt, were found from Maxianshan （马衔山） rock group, Yongjing （永靖） county, Gansu （甘肃） Province, China. According to the research on the characteristics of geology and petrology, the basic dike swarms, widely intruded in Maxianshan rock group, are divided into two phases by the authors. U-Pb isotope of zircons from the basic dikes above two phases is separately determined by LA-ICP-MS in the Key Laboratory of Continental Dynamics of Northwest University, China and the causes of formation of the zircons are studied using CL images. The formation age of the earlier phase of metagabbro dikes is （441.1±1.4） Ma （corresponding to the early stage of Early Silurian）, and the age of the main metamorphic period is （414.3±1.2） Ma （corresponding to the early stage of Early Devonian）. The formation age of the later phase of diabase dike swarms is （434±1.0） Ma （corresponding to the late stage of Early Silurian）. The cap- tured-zircons from diabase dike swarms saved some information of material interfusion by Maxianshan rock group （^207pb/206pb apparent ages are （2 325±3）-（2 573 ±6） Ma）, and some zircons from diabase dike swarms also saved impacted information by tectonic thermal event during the late period of Caledonian movement （^206pb/^238U apparent ages are （400±2）-（429±2） Ma）. By combining the results of the related studies, the basic dikes within Maxianshan rock group were considered to be formed in the transfer period, from subductional orogeny towards collisional orogeny, which represents geological records of NW-SE extension during regional NE-SW towards intense compression in the Central Qilian block.
文摘The Sr, Nd and Pb isotopic characteristics of the Wudang basic dyke swarms and basic volcanics of the Yaolinghe Group show that they were derived from the same multi\|component mixing source in the mantle. The Wudang basic dyke swarms have (\{\}\+\{87\}Sr/\{\}\+\{86\}Sr)\-i=\{0.6905\}～\{0.7061\}, ε\-\{Nd\}(t)=\{-1.9\}～\{5.0\}, Δ\{\}\+\{208\}Pb/\+\{204\}Pb=\{35.49\}～\{190.26\}, Δ\{\}\+\{207\}Pb/\{\}\+\{204\}Pb=4～85, low Th/Ta and a wide range of La/Yb ratios; and the basic volcanics of the Yaolinghe Group have (\{\}\+\{87\}Sr/\{\}\+\{86\}Sr)\-i=\{0.6487\}～\{0.7075\}, ε\-\{Nd\}(t)=\{0.11\}～\{3.94\}, Δ\{\}\+\{208\}Pb/\{\}\+\{204\}Pb=\{-81.58\}～\{219.95\}, Δ\{\}\+\{207\}Pb/\{\}\+\{204\}Pb=\{4.44\}～\{16.68\} and higher Th/Ta and La/Yb ratios, indicating that their source is a mixture of DM and EMII, and the basic volcanics of the Yaolinghe Group were contaminated by crust materials en rout to the surface. Based on the geochemical features of continental tholeiitic basalts and being products of different facies derived from the same source, it can be concluded that an important rifting event in the South Qinling basement block occurred during Neoproterozoic, followed by a setting of oceanic basin in the Early Paleozoic.
文摘Introduction 2013 saw the sixth anniversary of the formulation of Regulations of the People＇s Republic of China on Disclosure of Government Information （hereinafter referred to as the Regulations） and the fifth anniversary of their being put into effect. As the Regulations were stipulated and put into force,
文摘Recent geological study and survey on the scale of 1: 50000 in northern Guangxi have made some advancements: meta-basic-ultrabasic rocks which occured as bedding injection sheets in the Sanrnenjie formation of the Proterozoic Danzhou group and caused contact metamorphism or hydrothermal alteration in adjacent wallrocks, were originated in extensional environment. Basic rocks belong to deep-sea tholeiite. TLe meta-basic -ultrabasic rocks sufferred intense deformation partitioning, resulting in lenticular network which was composed of mylonite zones in highly de formed field and lensoids in less- or non-deformed field. This structural pattern was explained as "melange" or "non-rooted cool intrusion " by previous workers. The deformation partitioning was mainly pure shearing in the early stage plus simple shearing in the later stage. This evolution was closely related to progressive deformation of the Guangxi orogeny.
基金sponsored by the National Natural Science Foundation of China (Grant No.41430426)
文摘Wave ray theory is employed to study features of propagation pathways（rays） of vortex Rossby waves in typhoons with asymmetric basic flow, where the tangential asymmetric basic flow is constructed by superimposing the wavenumber-1 perturbation flow on the symmetric basic flow, and the radial basic flow is derived from the non-divergence equation. Results show that, in a certain distance, the influences of the asymmetry in the basic flow on group velocities and slopes of rays of vortex Rossby waves are mainly concentrated near the radius of maximum wind（RMW）, whereas it decreases outside the RMW. The distributions of radial and tangential group velocities of the vortex Rossby waves in the asymmetric basic flow are closely related to the azimuth location of the maximum speed of the asymmetric basic flow, and the importance of radial and tangential basic flow on the group velocities would change with radius. In addition, the stronger asymmetry in the basic flow always corresponds to faster outward energy propagation of vortex Rossby waves. In short, the group velocities, and thereby the wave energy propagation and vortex Rossby wave ray slope in typhoons, would be changed by the asymmetry of the basic flow.
