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Geological Characteristics and Zircon U-Pb Dating of Volcanic Rocks from the Beizhan Iron Deposit in Western Tianshan Mountains, Xinjiang, NW China 被引量:29
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作者 ZHANG Zuoheng HONG Wei +5 位作者 JIANG Zongsheng DUAN Shigang XU Lingang LI Fengming GUO Xincheng ZHAO Zhengang 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2012年第3期737-747,共11页
The Beizhan large iron deposit located in the east part of the Awulale metallogenic belt in the western Tianshan Mountains is hosted in the Unit 2 of the Dahalajunshan Formation as lens, veinlets and stratoid, and bot... The Beizhan large iron deposit located in the east part of the Awulale metallogenic belt in the western Tianshan Mountains is hosted in the Unit 2 of the Dahalajunshan Formation as lens, veinlets and stratoid, and both of the hanging wall and footwall are quartz-monzonite; the dip is to the north with thick and high-grade ore bodies downwards. Ore minerals are mainly magnetite with minor sulfides, such as pyrite, pyrrhotite, chalcopyrite and sphalerite. Skarnization is widespread around the ore bodies, and garnet, diopside, wollastonite, actinolite, epidote, uralite, tourmaline sericite and calcite are ubiquitous as gangues. Radiating outwards from the center of the ore body the deposit can be classified into skarn, calcite, serpentinite and marble zones. LA-ICP-MS zircon U-Pb dating of the rhyolite and dacite from the Dahalajunshan Formation indicates that they were formed at 301.3±0.8 Ma and 303.7±0.9 Ma, respectively, which might have been related to the continental arc magmatism during the late stage of subduction in the western Tianshan Mountains. Iron formation is genetically related with volcanic eruption during this interval. The Dahalajunshan Formation and the quartz-monzonite intrusion jointly control the distribution of ore bodies. Both ore textures and wall rock alteration indicate that the Beizhan iron deposit is probably skarn type. 展开更多
关键词 iron ore Zircon U-Pb dating SKARNIZATION Beizhan western Tianshan mountains
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Phase Equilibria of Hornblende-Bearing Eclogite in the Western Dabie Mountain,Central China 被引量:7
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作者 ZHANG Jingsen WEI Chunjing +1 位作者 LOU Yuxing SU Xiangli 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2009年第1期57-69,共13页
The high-pressure (HP) eclogite in the western Dabie Mountain encloses numerous hornblendes, mostly barroisite. Opinions on the peak metamorphic P-T condition, PT path and mineral paragenesis of it are still in disp... The high-pressure (HP) eclogite in the western Dabie Mountain encloses numerous hornblendes, mostly barroisite. Opinions on the peak metamorphic P-T condition, PT path and mineral paragenesis of it are still in dispute. Generally, HP eclogite involves garnet, omphacite, hornblendes and quartz, with or without glaucophane, zoisite and phengite. The garnet has compositional zoning with XMg increase, XCa and XMn decrease from core to rim, which indicates a progressive metamorphism. The phase equilibria of the HP eclogite modeled by the P-T pseudosection method developed recently showed the following: (1) the growth zonation of garnet records a progressive metamorphic PT path from pre-peak condition of 1.9-2.1 GPa at 508~C-514~C to a peak one of 2.3-2.5 GPa at 528~C-531~C for the HP eclogite; (2) the peak mineral assemblage is garnet+omphacite+glaucophane+quartz_+phengite, likely paragenetic with lawsonite; (3) the extensive hornblendes derive mainly from glaucophane, partial omphacite and even a little garnet due to the decompression with some heating during the post-peak stage, mostly representing the conditions of about 1.4-1.6 GPa and 580~C-640~C, and their growth is favored by the dehydration of lawsonite into zoisite or epidote, but most of the garnet, omphacite or phengite in the HP eclogite still preserve their compositions at peak condition, and they are not obviously equilibrious with the hornblendes. 展开更多
关键词 ECLOGITE HORNBLENDE peak P-T condition phase equilibrium PT path western Dabie mountain
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Selenium Enrichment in Cambrian Stratabound Gold Deposits in the Western Qinling Mountains 被引量:3
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作者 Liu Jiajun,Open Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou 550002Zheng Minghua, Chengdu Institute of Technology, Chengdu, Sichuan 610059Liu Jianming, Research Centre of Mineral Resources Exploration, Chinese Academy of Sciences,Beijing 100101Zhou Yufeng, Gu Xuexiang, Zhang Bin, Lin Li, Chengdu Institute of Technology, Chengdu, Sichuan 610059and Lu Wenquan Institute of Comprehensive Utilization of Mineral Resources, Chengdu, Sichuan 610041 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1997年第4期423-432,共10页
Stratabound gold deposits in the western Qinling Mountains occur in Cambrian chert formation composed of carbonaceous chert and carbonaceous slate. The distinctive chert formation provides important grounds for the mi... Stratabound gold deposits in the western Qinling Mountains occur in Cambrian chert formation composed of carbonaceous chert and carbonaceous slate. The distinctive chert formation provides important grounds for the mineralization and controls on the formation of gold deposits. Study shows that Se is exceptionally higher in both host rocks and gold orebodies. It may be recovered as a valuable component in ores for total utilization, and in some localities even independent Se orebodies (which are mined exclusively for Se) may be delineated. In gold ore Se mainly occurs as independent minerals or in the isomorphous form in sulphides and there is a positive correlation between Se and Au. 展开更多
关键词 stratabound gold deposit SELENIUM mineralization ENRICHMENT western Qinling mountains
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Upwelling Process of the Western Himalaya Mountains:Height and Velocity Estimation Evidenced by Formation and Evolution of the Zanda Basin,Tibet,China 被引量:3
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作者 ZHU Dagang MENG Xian' gang +5 位作者 SHAO Zhaogang YANG Chaobin HAN Jian'en YU Jia MENG Qingwei Lü Rongping 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2010年第2期280-295,共16页
Based on field geological survey, stratigraphic section measurement and indoor comprehensive investigation, the Zanda Basin's tectonic location in the Himalaya Plate was ascertained, and the formation and evolution o... Based on field geological survey, stratigraphic section measurement and indoor comprehensive investigation, the Zanda Basin's tectonic location in the Himalaya Plate was ascertained, and the formation and evolution of the Zanda Basin during the Pliocene to Early Pleistocene was classified as six stages: (a) primary rift-faulting stage, (b) quick rift-faulting Stage, (c) intensive rift-faulting stage, (d) stasis stage, (e) secondary rift-faulting stage, and (f) secondary quick rift-faulting stage. Based on this six-staged formation-evolution theory of the Zanda Basin, the upwelling process of the Western Himalaya Mountains from the Pliocene to Early Pleistocene was classified as the following five stages: (a) slow upwelling stage (5.4-4.4 Ma), (b) mid-velocity upwelling stage (4.4-3.5 Ma), (c) quick upwelling stage (3.5-3.2 Ma), (d) upwelling-ceasing stage (3.2-2.7 Ma), and (e) quick upwelling stage (2.7 Ma). Research has shown that in the duration from the Early Pliocene (4.7 Ma) to the End of Pliocene (2.67 Ma), which lasted 2.03 million years, the Himalaya Mountains had uplifted 1500 m at a velocity of 0.74 mm/a; this belongs to a mid-velocity upwening. During the 1.31 million years in the Early Stage of the Early Pleistocene, the Himalaya Mountains had risen up another 1500 m at a velocity of 1.15 mm/a; this is a rather quick upwelling. All of these data have shown that the upwelling of the Western Himalaya Mountains is along a complicated process with multi-stages, multi-velocities, and non-uniformitarian features. 展开更多
关键词 Zanda Basin Pliocene to Early Pleistocene basin evolution mountain upwelling western Himalaya mountains.
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Discovery of Radiolarian Fossils from the Aiketik Group at the Western End of the South Tianshan Mountains of Chinaand Its Implications 被引量:16
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作者 李曰俊 王招明 +3 位作者 吴浩若 黄智斌 谭泽金 罗俊成 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2002年第2期146-154,共9页
The Aiketik Group, distributed at the western end of the South TianshanMountains, China, is an important lithostratigraphic unit involved in the South Tianshan orogen. Itis separated from the adjacent rocks by faults.... The Aiketik Group, distributed at the western end of the South TianshanMountains, China, is an important lithostratigraphic unit involved in the South Tianshan orogen. Itis separated from the adjacent rocks by faults. Generally, the geologists ascribed it to the UpperCarboniferous according to Pseudostaffella sp., Profusulinella sp. and Fusulinella sp. found fromthe limestone and sandy limestone of Aiketik. Our radiolarian fossils were obtained from the chertsamples collected from the Haladaok section located at the upper Tuoshihan River. The fossils mainlyinclude Albaillella undulata Deflandre, Albaillella paradoxa Deflandre, Albaillella sp. aff. A.paradoxa Deflandre, Albaillella sp. cf. A. deflandrei Gourmelon, Albaillella sp., Albaillellaexcelsa Ishiga, Kito and Imoto (?), Belowea variabilis (Ormiston et Lane), Callella cf. C.parvispinosa Won, Entactinia cf. E. tortispina Ormiston et Lane, Entactinia aff. E. tortispinaOrmiston et Lane, Entactinia variospina Won, Entactinia sp., Eostylodictya rota (Won),Latentifistula impella (Ormistone et Lane) (?), Latentifistula turgita Omiston et Lane,Latentifistulidae gen. et. sp. indet. and Polyentactinia cf. aranea Gourmelon. Among them,Albaillella excelsa Ishiga, Kito and Imoto (?) is a Late Permian species with some elementsuncertain as there is only one poorly-preserved fossil of this species found so far. And tworadiolarian assemblages can be identified from the other fossils. One is the early EarlyCarboniferous assemblage represented by Albaillella undulata Deflandre, Albaillella paradoxa andAlbaillella sp. cf. A. deflandrei Gourmelon. And the other is the late Early Carboniferousassemblage represented by Eostylodictya rota (Won). This is the first discovery of radiolarianfossils in the Aiketik Group, also the first discovery of Late Permian radiolarian fossils in theSouth Tianshan Mountains. Meanwhile, this is the current westernmost sampling site of radiolarianfossils in the South Tianshan Mountains. 展开更多
关键词 western end of the South Tianshan mountains the Aiketik Group RADIOLARIAN Late Permian Early Carboniferous Middle Carboniferous
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Scattered Rural Settlements and Development of Mountainous Regions in Western Sichuan,China 被引量:3
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作者 GAO Yanjun CHEN Guojie SHEN Maoying 《Wuhan University Journal of Natural Sciences》 CAS 2007年第4期737-742,共6页
Making rural settlements of Mountainous Regions in Western Sichuan as the study objects and using symbolic statistical methods, then combining the case study of Daofu County, the paper analyzes the negative impact of ... Making rural settlements of Mountainous Regions in Western Sichuan as the study objects and using symbolic statistical methods, then combining the case study of Daofu County, the paper analyzes the negative impact of the scattered rural settlements on infrastructure construction, farmers' income increase and mountain ecological reconstruction in mountainous regions of western Sichuan. The results indicate that economic density is positively related to both rural settlements density (R^2=0.73) and rural population density (R^2=0.77), and it is the same for relationship between towns density and rural settlements density (R^2=0.88) and between towns density and economic density (R^2=0.71), and the scattered distribution pattern of the rural settlements and shortage of economic centers is a major factor to the lagged socioeconomic development. On the eco-economic zoning to Daofu County, the paper indicates the spatial distribution model and the industrial development model of the rural settlements need to be changed, and rural population should be concentrated in larger rural settlements with development of off-farm industries while infrastructure construction is to reinforced. 展开更多
关键词 mountainous regions in western Sichuan rural settlement scattered distribution DEVELOPMENT
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Soil Fertility Survey in Western Usambara Mountains, Northern Tanzania 被引量:3
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作者 P. A. NDAKIDEMI J. M. R. SEMOKA 《Pedosphere》 SCIE CAS CSCD 2006年第2期237-244,共8页
Soil samples from thirty sites representing four agro-ecological zones in the Western Usambara Mountains (WUM) of the Lushoto District in northern Tanzania were collected and analyzed for different nutrients. The resu... Soil samples from thirty sites representing four agro-ecological zones in the Western Usambara Mountains (WUM) of the Lushoto District in northern Tanzania were collected and analyzed for different nutrients. The results suggested that the major soil fertility constraint was P deficiency. On the basis of critical levels established in other areas, 90% of the soils were ranked as P deficient. This was followed by N, which was ranked as inadequate in 73% of the sites. Magnesium, K, and Ca also appeared limiting with 67%, 53% and 50% of the soils falling below the established critical values, respectively. A few soils (10%) were also found to contain exchangeable Al. The metallic micronutrients (Cu, Fe, and Zn) were adequate in all soils. Two sites had excessive Mn that could lead to toxicity in crops, and one was Mn deficient. 展开更多
关键词 土壤肥力 山地 肥力控制 肥沃性
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Thrust Propagation in the Aqqikkol Lake Area, the East Kunlun Mountains, Northwestern China 被引量:2
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作者 CUI Junwen, CHEN Wen, LI Pengwu, ZHANG Xiaowei and LI Li Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2003年第4期468-478,共11页
The western segment of the East Kunlun Mountains is one of the poorly studied regions in northwestern China. Through a structural analysis of the typical sections, we have the following views: (1) There is a very well... The western segment of the East Kunlun Mountains is one of the poorly studied regions in northwestern China. Through a structural analysis of the typical sections, we have the following views: (1) There is a very well developed fault system in the western segment of the East Kunlun Mountains and thrust propagation, normal slip and decoupling are the chief deformation events in this area. (2) Although the thrusting started in the Late Carboniferous and Late Triassic-Early Jurassic, strong activity took place in the Miocene-Quaternary when the Kumkol basin was strongly downwarped. (3) The tectonic pattern of coexistence of N-directed thrust propagation and S-directed normal slip in this area is consistent with the general tectonic pattern of the northern Qinghai-Tibet plateau and also very similar to that of the Himalayan region on the southern margin of the Qinghai-Tibet plateau, but their directions between the thrust propagation are opposite and all the strong thrust propagations occurred from the Miocene-Pliocene to Quaternary, a period featuring strong collision between the Indian plate and the Eurasian plate and abrupt uplift of the Qinghai-Tibet plateau. This oppositely directed thrust propagation and normal slip reveal such kinematic characteristics as symmetric propagations of deep-seated materials towards the north and south beneath the Qinghai-Tibet plateau and gravitational sliding of superficial materials towards the interior of the plateau. Therefore, the establishment of the fault system in the study area may provide an approach to the study of deep processes of the northern Qinghai-Tibet plateau and the construction of a unified geodynamic model for the uplift of the Qinghai-Tibet plateau. 展开更多
关键词 western segment of the East Kunlun mountains thrust propagation normal slip plate collision dynamic model
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Variations of Snow Temperature and their Influence on Snow Cover Physical Parameters in the Western Tianshan Mountains,China 被引量:3
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作者 CHEN Xia WEI WenShou +1 位作者 LIU MingZhe GU GuangQin 《Journal of Mountain Science》 SCIE CSCD 2011年第6期827-837,共11页
This article discussed about snow temperature variations and their impact on snow cover parameters.Automatic temperature recorders were used to sample at 10-minute intervals at the Tianshan Station for Snow-cover and ... This article discussed about snow temperature variations and their impact on snow cover parameters.Automatic temperature recorders were used to sample at 10-minute intervals at the Tianshan Station for Snow-cover and Avalanche Research,Chinese Academy of Sciences.10-layer snow temperature and the snow cover parameters were measured by the snow property analyzer (Snow Fork) in its Stable period,Interim period and Snow melting period.Results indicate that the amplitude of the diurnal fluctuation in the temperature during Snow melting period is 1.62 times greater than that during Stable period.Time up to the peak temperature at the snow surface lags behind the peak solar radiation by more than 2.5 hours,and lags behind the peak atmospheric temperature by more than 0.2 hours during all three periods.The optimal fitted function of snow temperature profile becomes more complicated from Stable period to Snow melting period.22 h temperature profiles in Stable period are the optimal fitted by cubic polynomial equation.In Interim period and Snow melting period,temperature profiles are optimal fitted by exponential equation between sunset and sunrise,and by Fourier function when solar radiation is strong.The vertical gradient in the snow temperature reaches its maximum value at the snow surface for three periods.The peak of this maximum value occurs during Stable period,and is 4.46 times greater than during Interim period.The absolute value of temperature gradient is lower than 0.1°C cm-1 for 30 cm beneath snow surface.Snow temperature and temperature gradient in Stable period~Interim period indirectly cause increase (decrease) of snow density mainly by increasing (decreasing) permittivity.While it dramatically increases its water content to change its permittivity and snow density in Snow melting period. 展开更多
关键词 温度变化 天山西部 物理参数 雪盖 中国 最佳拟合函数 积雪密度 峰值温度
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Chemostratigraphy and lithological characters of Neoproterozoic cap carbonates from the Kuruktag Mountain, Xinjiang, western China 被引量:1
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作者 杨瑞东 张传林 +1 位作者 王伯勋 罗新荣 《Chinese Journal Of Geochemistry》 EI CAS 2007年第2期132-142,共11页
The Neoproterozoic Era includes some of the most largest ice ages in the geological history. The exact number of glaciations is unknown, though there were at least two events of global glaciation. Neoproterozoic glaci... The Neoproterozoic Era includes some of the most largest ice ages in the geological history. The exact number of glaciations is unknown, though there were at least two events of global glaciation. Neoproterozoic glacial deposits in the Kuruktag Mountain, Xinjiang, western China have proven that there had occurred three discrete Neoproterozoic glaciations. Diamictite units occurred in the Bayisi, Tereeken, and Hankalchough formations, carbonate units were recognized among the diamictites and immediately overlied the Bayisi, Tereeken and Hankalchough diamictites. Carbonates at the top of the Bayisi Formation are characterized by the dolo-sility stones with negative δ13C values ranging from -4.10‰ to -8.17‰ (PDB), comparable to the Sturtian cap carbonates that overlie the Sturtian glacial deposits from other Neoproterozoic sequences. Carbonates overlying the Tereeken Formation are characterized by the pinkish cap dolostones (ca. 10 m thick) with negative δ13C values ranging from -2.58‰ to -4.77‰ (PDB), comparable to the Marinoan cap carbonates. The cap is also characterized by tepee-like structures, barite precipitates and pseudomorphous aragonite crystal fan limestones. Carbonates at the top of the Hankalchough Formation are characterized by subaerial exposure crust (vadose pisolite structure, calcareous crust structure) dolostones with negative δ13C values ranging from -4.56‰ to -11.45‰ (PDB) and the calcareous crust dolostones, implying that the Hankalchough cap carbonates differ from either the Sturtian or Marinoan cap carbonates in sedimentary environment and carbon isotopic composition. In addition, it is suggested the Hankalchough glaciation belongs to a terrestrial glaciation and it is the third largest glaciation during the Neoproterozoic period on the Tarim platform. 展开更多
关键词 新疆 库鲁克塔格山 新元古代帽 成碳酸盐岩 化学地层学 岩石学特性
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Zircon Dating and Geological Implications of Granitic Gneiss in the Metamorphic Zone of Gaoligong Mountains in Western Yunnan, China 被引量:2
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作者 TAN Xiaohong ZHAO Bo +2 位作者 LI Xikang XU Zhangbao ZHANG Zhen 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2013年第2期440-453,共14页
The general classification of intermediate-acid intrusive rocks in the metamorphic zone of Gaoligong Mountains as one of the metamorphic terranes of Proterozoic Gaoligong Mountains is problematic regarding the intrusi... The general classification of intermediate-acid intrusive rocks in the metamorphic zone of Gaoligong Mountains as one of the metamorphic terranes of Proterozoic Gaoligong Mountains is problematic regarding the intrusion stage and age, as well as the subsequent metamorphism and deformation. In this study, we investigated granitic gneiss in the metamorphic zone of Gaoligong Mountains based on the 1:50,000 regional geological survey of Qushi Street (2011-2013) and SHRIMP U-Pb zircon geochronology. Results showed that the SHRIMP U-Pb zircon dating of granitic gneiss ranged from 163.5±5.7 Ma to 74.0±2.0 Ma. Thus, the granitic gneiss was grouped into orthometamorphic rocks (metamorphic intrusions). The dating data of granite rocks associated with intense metamorphism and deformation were divided into three groups, 163.5±5.7 to 162.3±3.1 Ma, 132.2-101.0 Ma and 99.4±3.5-74.0±2.0 Ma, which respectively represented three independent geologic events including an important magma intrusion with superimposed metamorphic effects in the late Middle Jurassic, regional dynamic metamorphism and superimposed reformation of fluid action in the early Cretaceous, and dynamic metamorphism dominated by ductile shear and metamorphism starting from the late Cretaceous. 展开更多
关键词 Metamorphic zone granitic gneiss U-Pb zircon age Gaoligong mountains western Yunnan
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Source process of the 14 November 2001 western Kunlun Mountain M_S=8.1 earth-quake
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作者 ZHOU Yun-hao(周云好) +3 位作者 CHEN Zhang-li(陈章立) MIAO Fa-jun(缪发军) 《Acta Seismologica Sinica(English Edition)》 CSCD 2004年第z1期9-21,共8页
Based on digital teleseismic P-wave seismograms recorded by 28 long-period seismograph stations of the global seismic network, source process of the November 14, 2001 western Kunlun Mountain MS=8.1 (MW=7.8) earth- q... Based on digital teleseismic P-wave seismograms recorded by 28 long-period seismograph stations of the global seismic network, source process of the November 14, 2001 western Kunlun Mountain MS=8.1 (MW=7.8) earth- quake is estimated by a new inversion method. The result shows that the earthquake is a very complex rupture event. The source rupture initiated at the hypocenter (35.95°N, 90.54°E, focal depth 10 km, by USGS NEIC), and propagated to the west at first. Then, in several minutes to a hundred minutes and over a large spatial range, several rupture growth points emerged in succession at the eastern end and in the central part of the finite fault. And then the source rupture propagated from these rupture growth points successively and, finally, stopped in the area within 50 km to the east of the centroid position (35.80°N, 92.91°E, focal depth 15 km, by Harvard CMT). The entire rupture lasted for 142 s, and the source process could be roughly separated into three stages: The first stage started at the 0 s and ended at the 52 s, lasting for 52 s and releasing approximately 24.4% of the total moment; The sec- ond stage started at the 55 s and ended at the 113 s, lasting for 58 s and releasing approximately 56.5% of the total moment; The third stage started at the 122 s and ended at the 142 s, lasting for 20 s and releasing approximately 19.1% of the total moment. The length of the ruptured fault plane is about 490 km. The maximum width of the ruptured fault plane is about 45 km. The rupture mainly occurred within 30 km in depth under the surface of the Earth. The average static slip in the underground rocky crust is about 1.2 m with the maximum static slip 3.6 m. The average static stress drop is about 5 MPa with the maximum static stress drop 18 MPa. The maximum static slip and the maximum stress drop occurred in an area within 50 km to the east of the centroid position. 展开更多
关键词 digital seismograms INVERSION western Kunlun mountain MS=8.1 earthquake source rupture process
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Primary Deformation Analyses of High Pressure Metamorphic Rock in Western Dabie Mountain Area
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作者 WeiChangshan LuGuxian +1 位作者 ZhangYeming XiongChengyun 《Journal of China University of Geosciences》 SCIE CSCD 2004年第2期220-223,共4页
In the western Dabie Mountain area, the eclogites have similar compositions and tectonic environment, which could be contrastively researched. Except for the reservation of the early structural deformation inside and ... In the western Dabie Mountain area, the eclogites have similar compositions and tectonic environment, which could be contrastively researched. Except for the reservation of the early structural deformation inside and outside of the eclogite lens, there is no obvious difference between the characteristics of the foliation and lineation in the eclogite lens from the one in surrounding region. So this paper concludes that the eclogites or blueschists (high pressure metamorphic rocks, i. e. HPM) are basically situated in the original position. The eclogites are mostly superposed by the ductile shear zone and show the feature of structural displacement, but so far we have not discovered any large scale structural zone to uplift eclogite return. Based on the analyses of finite strain measure, petrofabric analysis and TEM image for some minerals such as quartz and garnet, we could efficiently know the deforming characteristics of the eclogite in the prophase and anaphase of the main deforming epoch, and finally determine the forming condition of eclogite according to the strain and the differential stress. This paper puts forward preliminary conclusion that some HPM rocks could be formed by the deep layer embedding and local stress concentration in the process of regional metamorphism. 展开更多
关键词 ECLOGITE DEFORMATION finite strain measure western Dabie mountain area
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Estimation of the stress levels in the focal region before and after the 2001 M=8.1 Western Kunlun Mountain Pass earth-quake
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作者 陈学忠 《Acta Seismologica Sinica(English Edition)》 EI CSCD 2005年第6期651-655,共5页
A method estimating the stress level in the focal region of an earthquake is proposed here. Taking the 2001 M=8.1 Western Kunlun Mountain Pass earthquake as an example, we estimate its stress level in the focal region... A method estimating the stress level in the focal region of an earthquake is proposed here. Taking the 2001 M=8.1 Western Kunlun Mountain Pass earthquake as an example, we estimate its stress level in the focal region before and after it by this method. The results show that the stress level in the focal region just prior to the initiation of this event is approximately 6.3-8 MPa, and about 5-6.7 MPa remained in the focal region after its occurrence. The stress in the focal region decreased by roughly twenty percent after this event. 展开更多
关键词 western Kunlun mountain Pass earthquake focal region stress level
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Geochemistry of Sediments from a Subalpine Lake Sedimentary Succession in the Western Nanling Mountains,Southern China:Implications for Catchment Weathering During the Last 15400 Years
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作者 WANG Bingxiang ZHONG Wei +3 位作者 ZHU Chan OUYANG Jun WEI Zhiqiang SHANG Shengtan 《Chinese Geographical Science》 SCIE CSCD 2022年第3期537-548,共12页
In the present work,15400 yr old geochemical records of a core from the subalpine Daping swamp are presented with the aim to examine the relationship between the chemical weathering and the climatic changes in the reg... In the present work,15400 yr old geochemical records of a core from the subalpine Daping swamp are presented with the aim to examine the relationship between the chemical weathering and the climatic changes in the region of the western Nanling Mountains,China.The climate of the study region was deeply controlled by the East Asian summer monsoon.The results indicate that,in the past 15400 yrs,the values of chemical index of alteration(CIA)ranged from 73.9%to 88.2%(mean:85.3%),suggested a medium and high intensity of chemical weathering.The local exogenous clastic materials,which were derived from the weathered residues,played a key role in contributing towards the sediments.Since the climate-induced chemical weathering exerted strong influences on the geochemical features of weathered residues,the geochemical characteristics of the sediments were deeply impacted by climatic conditions.Wetter and warmer conditions would favor increased chemical weathering,resulting in more leaching of soluble and mobile elements(e.g.,Ba and Sr)and leaving the resistant and immobile elements(e.g.,Al and Ti)enriched in the weathered residues.These materials were then eroded and transported into the lake,and led to the sediments characterized by the characteristic of having depleted soluble elements.In contrast,dry and cold conditions would result in an opposite trend.In this sense,the geochemical records can serve as proxies to indicate changes of chemical weathering intensity,which were closely related to the evolution of summer monsoon. 展开更多
关键词 lacustrine sediments chemical weathering asian summer monsoon last deglacial western Nanling mountains China
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Spatiotemporal variations in the growth status of declining wild apple trees in a narrow valley in the western Tianshan Mountains, China
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作者 QIU Dong TAO Ye +6 位作者 ZHOU Xiaobing Bagila MAISUPOVA YAN Jingming LIU Huiliang LI Wenjun ZHUANG Weiwei ZHANG Yuanming 《Journal of Arid Land》 SCIE CSCD 2022年第12期1413-1439,共27页
Malus sieversii(wild apple tree),only distributed in the Tianshan Mountains in Central Asia,is a tertiary relic species and an ancestral species of cultivated apples.However,existing natural populations of wild apple ... Malus sieversii(wild apple tree),only distributed in the Tianshan Mountains in Central Asia,is a tertiary relic species and an ancestral species of cultivated apples.However,existing natural populations of wild apple trees have been declining.To date,spatiotemporal variations in the growth status of declining wild apple trees and influencing factors in the narrow valley areas in the Tianshan Mountains remain unclear.In this study,field investigation and sampling were carried out in three years(2016-2018)at four elevations(1300,1400,1500,and 1600 m)in the Qiaolakesai Valley(a typical longitudinal narrow valley in the Yili River Valley)of the western Tianshan Mountains in Xinyuan County,Xinjiang Uygur Autonomous Region,China.Projective coverage,dead branch percentage,and 18 twig traits(these 20 parameters were collectively referred to as plant traits)were determined to comprehensively reflect the growth status of declining wild apple trees.The values of dead branch percentage ranged from 36%to 59%,with a mean of 40%.Year generally showed higher impact on plant traits than elevation.In 2017 and 2018,projective coverage,leaf size,leaf nitrogen concentration,and nitrogen to phosphorous ratio were markedly higher than those in 2016.However,dead branch percentage and leaf and stem phosphorous concentrations showed the opposite trend.Most of the topological parameters of plant trait networks differed in the three years,but the strength of trait-trait association increased year by year.The mean difference between day and night temperatures(MDT),annual accumulative precipitation,soil electrical conductivity,and soil pH had the greatest impact on the plant trait matrix.The growth status of declining wild apple trees was directly and positively affected by MDT and leaf size.In conclusion,the growth of declining wild apple trees distributed in the narrow valley areas was more sensitive to interannual environmental changes than elevation changes.The results are of great significance for further revealing the decline mechanism of wild apple trees in the Tianshan Mountains. 展开更多
关键词 Malus sieversii plant attributes plant trait network elevation gradient meteorological factor western Tianshan mountains
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Sensitivity of digital elevation models:The scenario from two tropical mountain river basins of the Western Ghats,India 被引量:1
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作者 Jobin Thomas Sabu Joseph +1 位作者 K.P.Thrivikramji K.S.Arunkumar 《Geoscience Frontiers》 SCIE CAS CSCD 2014年第6期893-909,共17页
The paper evaluates sensitivity of various spaceborne digital elevation models (DEMs), viz., Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Shuttle Radar Topography Mapping Mission (SRTM... The paper evaluates sensitivity of various spaceborne digital elevation models (DEMs), viz., Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Shuttle Radar Topography Mapping Mission (SRTM) and Global Multi-resolution Terrain Elevation Data 2010 (GMTED), in comparison with the DEM (TOPO) derived from contour data of 20 m interval of Survey of India topographic sheets of 1 : 50,000 scale. Several topographic attributes, such as elevation (above mean sea level), relative relief, slope, aspect, curvature, slope-length and -steepness (LS) factor, terrain ruggedness index (TRI), topo- graphic wetness index (TWI), hypsometric integral (lhyp) and drainage network attributes (stream number and stream length) of two tropical mountain river basins, viz. Muthirapuzha River Basin and Pambar River Basin are compared to evaluate the variations. Though the basins are comparable in extent, they differ in respect of terrain characteristics and climate. The result.,; suggest that ASTER and SRTM provide equally reliable representation of topography portrayed by TOP() and the topographic attributes extracted from the spaceborne DEMs are in agreement with those derived from TOPO. Despite the coarser resolution, SRTM shows relatively higher vertical accuracy (RMSE -- 23 and 20 m respectively in MRB and PRB) compared to ASTER (RMSE - 33 and 24 m) and GMTED (RMSE - 59 and 48 m). Vertical accuracy of all the spaceborne DEMs is influenced by relief of the terrain as well as type of vegetation. Further, GMTED shows significant deviation for most of the attributes, indicating its inability for mountain-river-basin-scale studies. 展开更多
关键词 DEM ASTER SRTM GMTEDTropical mountain river basins western Ghats
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The Key Influence of Fluid in the Preserves, Mineral Assemblages, Compositionsand Structures: Study from High-Pressure Eclogite and Its Amphibolization in the Western Dabie Mountains,Central China
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作者 LOU Yuxing ZHANG Cong +1 位作者 WEI Chunjing LIU Xiaochun 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期227-,共1页
Pseudosection modeling for the garnet amphibolite samples from the Western Dabie Mountains show they have experienced similar HP metamorphic evolution with that of the adjected eclogites.The common assemblage of
关键词 UHP Compositionsand Structures Mineral Assemblages Study from High-Pressure Eclogite and Its Amphibolization in the western Dabie mountains Central China The Key Influence of Fluid in the Preserves
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The Key Influence of Fluid in Metamorphic Rock Preserves, Mineral Assemblages, Compositions and Structures: Study from High-Pressure Eclogite and Its Amphibolization in the Western Dabie Mountains,Central China
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作者 LOU Yuxing ZHANG Cong +2 位作者 WEI Chunjing LIU Xiaochun WANG W-(RZ) 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期228-230,共3页
The most of high/ultrahigh-pressure(HP/UHP)terranes of the world are characterized by the occurrence of numerous pods,lenses or layered blocks of eclogite and amphibolites(e.g.O’Brien,1997;Elvevold and Gilotti,2000;Z... The most of high/ultrahigh-pressure(HP/UHP)terranes of the world are characterized by the occurrence of numerous pods,lenses or layered blocks of eclogite and amphibolites(e.g.O’Brien,1997;Elvevold and Gilotti,2000;Zhang et al.,2003;and references there in).Field and petrological features suggest that amphibolites should 展开更多
关键词 UHP Mineral Assemblages Study from High-Pressure Eclogite and Its Amphibolization in the western Dabie mountains Central China The Key Influence of Fluid in Metamorphic Rock Preserves Compositions and Structures
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Study on security and protection of original ecotourism resources in the mountain areas of western Guangxi
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作者 Wu Lianglin Zhou Yongzhang +2 位作者 Chen Zhishen Ding dian Yan Xiaoping 《Ecological Economy》 2008年第1期41-48,共8页
Original ecotourism resources mainly refer to natural and human original ecotourism resources, and it's of fragility, rarity and irreversibility. As a valuable historic heritage and important tourism resources, it... Original ecotourism resources mainly refer to natural and human original ecotourism resources, and it's of fragility, rarity and irreversibility. As a valuable historic heritage and important tourism resources, it plays a significant role in developing tourism and economy in such areas as the underdeveloped areas, the mountain areas and mi-nority areas. The tourism resources in the western mountain areas of Guangxi owe superiorities and characteristics to their original ecology. Yet, western Guangxi is an ethnic region with fragile karst eco-environment, so it is special to exploit the tourism resources. The paper defines original ecotourism and analyses the specialties and advantages of the original ecotourism resources as well as the frailty of the ecotourism resources of the region. The ways of thinking are put forward for safe preservation and sustainable development of the original ecotourism resources, i.e. carrying out measures for the multi-grade protection of heritage resources, setting up a ethnic ecomuseum/ ethnic culture eco-park and a gene pool of ethnic cultures, etc. 展开更多
关键词 广西 山地 原始生态资源 自然文化遗产 种族文化
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