检索结果-南通市图书馆

Zircon and apatite fission track analyses on mineralization ages and tectonic activities of Tuwu-Yandong porphyry copper deposit in northern Xinjiang, china

在线全文

学校读者我要写书评

暂无评论

Science china earth {2. 2007年第12期50卷 1787-1795页

作者： YUAN WanMing1,BAO ZengKuan2.DONG JinQuan2.GUO ZhaoJie3 & DENG Jun1 1 State Key Laboratory of Geological Processes and mineral resources,{2. university of Geosciences,beijing100083,{2. 2.Laboratory of Nuclear Analysis Techniques,Institute of High Energy Physics,Chinese Academy of sciences,beijing 100039,{2. 3 Department of Geology,Peking university,beijing 100871,{2. State Key Laboratory of Geological Processes and mineral resources China University of Geosciences Beijing China Laboratory of Nuclear Analysis Techniques Institute of High Energy Physics Chinese Academy of Sciences Beijing China Department of Geology Peking University Beijing China

The mineralization ages reported in the past in the Tuwu-Yandong copper district not only are different,but also fall into the Hercynian *** study has achieved 9 zircon and 7 apatite fission track analysis *** zircon fission track ages range from 158 Ma to 2.9 Ma and the apatite ages are between 64 Ma and 140 *** mineralization accords with the regional tectonics in the copper *** consider that the zircon fission track age could reveal the mineralization age based on annealing zone temperature of 140―300℃ and retention temperature of ～2.0℃ for zircon fission track,and metallogenetic temperature of 12.―350℃ in this ore *** three mineralization epochs have been identified,i.e.,2.9―2.6 Ma,2.2.2.0 Ma and 165―158 Ma,and indicate occurrence of the min-eralization in the Indosinian and Yanshan *** to apatite fission track ages,the three tectonic-mineralizing epochs are 140―132.Ma,109―97 Ma and 64 Ma,which means age at about 100℃ after the *** three epochs lasted 146 Ma,108 Ma and about 100 Ma from ～2.0℃ to ～100℃ and trend decrease from early to *** is shown by the fission track modeling that this district underwent three stages of geological thermal histories,stable in Cretaceous and cooling both before Cretaceous and after 2. Ma.

关键词： mineralization age, tectonic epoch, fission track, zircon, apatite, Tuwu-Yandong, Xinjiang

The crustal structure under Sanjiang and its dynamic implications:Revealed by seismic reflection/refraction profile between Zhefang and Binchuan,Yunnan

在线全文

学校读者我要写书评

暂无评论

Science china earth {2. 2005年第9期48卷 1329-1336页

作者： ZHANG Zhongjie1, BAI Zhiming1, WANG Chunyong2. TENG Jiwen1, Lü Qingtian3, LI Jiliang1, LIU Yifeng1 & LIU Zhenkuan4 1. Institute of Geology and Geophysics, Chinese Academy of sciences, beijing 10002.,{2. 2. Institute of Geophysics,{2. Seismological Bureau, beijing 100085,{2. 3. Institute of Deposition Resource, Chinese Academy of Geosciences, beijing 100037,{2. 4. school of Exploration and Information,{2. university of Geosciences, beijing 100083,{2. Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Institute of Geophysics China Seismological Bureau Beijing China Institute of Deposition Resource Chinese Academy of Geosciences Beijing China school of Exploration and Information China University of Geosciences Beijing China

The fault belts in Sanjiang mainly include Jinshajiang-Honghe fault, Lancangjiang fault and Nujiang fault (called Sanjiang faults) in western Yunnan Province, china. By interpreting the wide-angle seismic reflection/refraction profile between Zhefang and Binchuan, which crosses Tengchong and Baoshan blocks in Dianxi (western Yunnan) tectonic zone, we recon- struct the crustal structure with seismic traveltime tomography for crustal P-wave velocity and the seismic scattering image for crustal seismic reflection structure. In this paper, we firstly present the crustal structure images of P-wave velocity and seismic reflection under the wide-angle seismic profile. These results demonstrate that, the crustal velocity structure and seismic reflec- tion structure along the profile can be divided into 3 segments, and there is an obvious difference of crustal structure among the eastern, the western and the middle segment. Generally, crustal P-wave velocities in the Baoshan segment are 0.1―0.2.km/s slower and seismic reflection am- plitudes from Moho discontinuity are stronger than the other 2.segments. In the studied area, crustal thickness is about 40 km, and shows the thickening tendency from west to east along the profile. Additionally, it can be seen that there is one strong-amplitude seismic reflection event as bright points at the depths of 8―10 km, along the segment of 80―115 km of the profile (south- ward of Tengchong); and seismic reflection wave-field from Moho discontinuity varies obviously along the lateral direction. Finally, we make some discussions on the crustal thickening pattern in the Sanjiang fault belt, structural environment of earthquake development and the contact rela- tionship between the Tengchong block, Banshan block and Luxi trough.

关键词： Sanjiang area wide-angle seismic profile crustal structure.

The Construction of Natural Disaster Database of Alxa and Periodicity Analysis

在线全文

学校读者我要写书评

暂无评论

地学前缘 2009年第S1期16卷 300-301页

作者： Yan Zheng,Mingzhong Tian,Siwen Liu,Chao Ma school of the earth {2. and resources,china university of Geo{2.(beijing),beijing 100083,china.

A compilation of all meaningful historical data of natural-disasters taken place in Alxa of inner-Mongolia is used here for the construction of a 65 Ma high precision *** data in the database are divided into subsets ... 详细信息

关键词： Alxa natural disaster databases periodicity

Land cover changes based on plant successions: Deforestation, rehabilitation and degeneration of forest in the upper Dadu River watershed

在线全文

学校读者我要写书评

暂无评论

Science china earth {2. 2005年第12期48卷 2214-2230页

作者： YAN Jianzhong1,2.3, ZHANG Yili1, BAI Wanqi1, LIU Yanhua4, BAO Weikai5, LIU Linshan1, 2.& ZHENG Du1 1. Institute of Geographic sciences and Natural resources Research, Chinese Academy of sciences, beijing 100101, china 2. Graduate school of the Chinese Academy of sciences, beijing 100039, china 3. College of resources and Environment, Southwest Agricultural university, Chongqing 400716, china 4. The Ministry of Science and Technology, P. C. china, beijing 100862. china 5. Chengdu Institute of Biology, Chinese Academy of sciences, Chengdu 610041, china Institute of Geographic sciences and Natural resources Research Chinese Academy of Sciences Beijing China Graduate school of the Chinese Academy of sciences Beijing China College of resources and Environment Southwest Agricultural University Chongqing China The Ministry of Science and Technology P. C. China Beijing China Chengdu Institute of Biology Chinese Academy of Sciences Chengdu China

To link regional land use/cover changes with environmental effects, land cover changes are required to reflect vegetation successions, whereas the land cover classification systems commonly used nowadays cannot serve this purpose. In this paper, a new land cover classification system is established in which land covers are classified by the vegetation succes-sions, taking Zamtang County, Barkam County and Jinchuan County in the upper Dadu River watershed as a study area. Using multi-temporal remote sensing images, the land cover data of 1967, 1986 and 2.00 are obtained by means of integration of unsupervised classification and visual interpretation methods. The database facilitates the study of land use/cover changes, en-vironmental effects and ecological construction. Land cover changes reflect the main ecological processes in the upper Dadu River watershed. The landscape composed mainly of grasslands, wildwoods and alpine scrubs in 1967 was changed to that of grasslands, secondary forests, al-pine scrubs, fragmentary wildwoods, artificial forests, secondary scrubs in 2.00, meanwhile, the landscape got more fragmentized. The total area of the forests decreased by 9.43%. Study results have shown the process of restoration of logged areas in forest centers. From 1967 to 2.00, only 6.86 percents of logged areas were converted to shrubs, meadows or crop-lands, and the rest were converted into artificial forests or secondary forests. So the ecological shelter functions will be restored, stage by stage. Firewood collection, charcoal production and overgrazing are the three major triggers for the extensive degradation of alpine oak forests, Sa-bina tibetica forests and meadows. The arid valley grasslands expanded too. The degradation of vegetation in the southern slopes impairs ecological shelter functions and affects livelihood of local residents, so it is essential to find effective measures for ecological restoration and recon-struction. Field investigations have found

关键词： land use/cover classification, upper Dadu River watershed, vegetation successions, GIS, RS.

Identifying rock blocks based on hierarchical rock-mass structure model

在线全文

学校读者我要写书评

暂无评论

Science china earth {2. 2009年第10期52卷 1612-1623页

作者： XU NengXiong school of Engineering and Technology, china {2. of Geosciences, beijing 100083, china school of Engineering and Technology China University of Geosciences Beijing China

Rock-masses are divided into many closed blocks by deterministic and stochastic discontinuities and engineering interfaces in complex rock-mass engineering. Determining the sizes, shapes, and adjacent relations of blocks is important for stability analysis of fractured rock masses. Here we propose an algorithm for identifying spatial blocks based on a hierarchical 3D Rock-mass Structure Model (RSM). First, a model is built composed of deterministic discontinuities, engineering interfaces, and the earth's surface, and the deterministic blocks surrounded by these interfaces are traced. Then, in each deter-ministic block, a network model of stochastic discontinuities is built and the stochastic blocks are traced. Building a unitary wire frame that connects all interfaces seamlessly is the key for our algorithm to identify the above two kinds of blocks. Using this algorithm, geometric models can be built for block theory, discrete element method, and discontinuous deformation analysis.

关键词： rock-mass engineering discontinuity block identification 3D Rock-mass Structure Model network model of stochastic discontinuities

3D Geological Modeling with Multi-source Data Integration in Polymetallic Region:A Case Study of Luanchuan,Henan Province,china

在线全文

学校读者我要写书评

暂无评论

地学前缘 2009年第S1期16卷 166-167页

作者： Gongwen Wang~(1,2.,Shouting Zhang~(1,2.,Changhai Yan~3,Yaowu Song~3,Limei Wang~1 1.school of earth {2. and resources,china university of Geo{2.(beijing),beijing 100083,china. 2.State Key laboratory of Geological Processes and mineral resources,china university of Geo{2.,beijing 100083,china 3.Henan Institute of Geological Survey,Zhengzhou 450007,china

The development of 3D geological models involves the integration of large amounts of geological data,as well as additional accessible proprietary lithological, structural,geochemical,geophysical,and borehole ***,the case study area,southwestern Henan Province,is an important molybdenum-tungsten -lead-zinc polymetallic belt in china.

关键词： 3D geological modeling multi-source data mineral exploration metallogenic model virtual geological section Luanchuan polymetallic region

Lead-Zinc-Silver Metallogenic Prediction Based on Weights of Evidence Approach:A case Study in Tuotuohe Region,Qinghai,china

在线全文

学校读者我要写书评

暂无评论

地学前缘 2009年第S1期16卷 177-178页

作者： Yan Sun~(1,2,3),Xunlian Wang~3,Jianping Chen~(1,2,3),Qian Wang~(1,2,3) 1.Institute of High and New Techniques Applied to Land resources,china university of Geosciences(beijing),beijing 100083, china. 2.beijing Key Laboratory of Development and Research for Land resources Information,china university of Geosciences (beijing),beijing 100083,china 3.school of earth sciences and resources,china university of Geosciences(beijing) beijing 100083,china

Tuotuo River region(E91°-E93°,N33°-N 35°) is located in southwest Qinghai Province,*** lies in one of the most important metallogenic belts in china—Northwest Sanjiang Metallogenic Belt,due to which Tuotuo River region can be of very high metal mineral potential not only in Qinghai Province but also *** this research,multisource data sets including geological,geochemical,geophysical, and remotely sensed images were integrated for mineral potential analysis with GIS *** the guidance of regional metallogenic features and deposit-forming geologic anomaly theories,evidential layers were obtained from these sets,which

关键词： Sanjiang metallogenic belt Tuotuo River lead-zinc-silver GIS Weights of Evidence minerogenic prediction

Development of environmental monitoring satellite systems in china

在线全文

学校读者我要写书评

暂无评论

Science china earth {2. 2010年第S1期53卷 1-7页

作者： LI GuoPing1 & CAO ChunXiang2.1 school of earth and Space {2.,Peking university,beijing 100871,china 2.State Key Laboratory of Remote Sensing Science,Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of {2. and beijing Normal university,beijing 100101,china school of earth and Space {2. Peking University Beijing China State Key Laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing China

With the increase in global environmental problems,the necessity and urgency of remote sensing technology being applied to environmental monitoring has been widely recognized around the *** has launched the environment and disaster monitoring and forecasting small satellite constellation HJ-1A/B and the FY3 atmosphere and environmental satellite,but they still cannot fully satisfy requirements for environmental *** paper summarizes the current status of satellite environmental monitoring in china and the existing problems of inadequate load design and low data utilization efficiency,and discusses the demand for environmental monitoring *** on the development of foreign satellite systems for environmental monitoring,the future development and key tasks of the environmental monitoring satellite system in china is discussed,as are some related initiatives.

关键词： environmental satellite environmental monitoring global climate change specialty load satellite system

Two new species of Vestrogothia (Phosphatocopina, Crustacea) of Orsten-type preservation from the Upper Cambrian in western Hunan, South china

在线全文

学校读者我要写书评

暂无评论

Science china earth {2. 2009年第6期52卷 784-796页

作者： ZHANG HuaQiao1,2.& DONG XiPing1,2.1 school of earth and Space {2.,Peking university,beijing 100871,china 2.State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of {2.,Nanjing 2.0008,china school of earth and Space {2. Peking University Beijing China State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing China

Although fossils of Orsten-type preservation represented by Skaracarida and Phosphatocopina were first reported from the Middle and Upper Cambrian in western Hunan, South china in 2.05, diversified phosphatocopine species have never been appropriately described and elucidated in terms of their evolutionary relationships. Here, we described two new species of Phosphatocopina, Vestrogothia anterispinata sp. nov. and V. bispinata sp. nov. The evolutionary relationship among all the valid species of Phosphatocopina is discussed and the phylogeny of Phosphatocopina is reestablished using cladistic analysis. Accordingly, phosphatocopines primitively evolved along two lineages: one evolved towards the emergence of lobes; the other evolved towards the emergence of dorsal spines. Respectively, lobes originated independently three times, and dorsal spines originated only once. With regard to the dorsal rims, interdorsum originated first, whereas dorsal furrow originated independently twice on the basis of interdorsum. Probably Hesslandona may represent a polyphyletic group, whereas Vestrogothia a monophyletic group.

关键词： fossils of Orsten-type preservation Vestrogothia Phosphatocopina Crustacea evolution phylogeny Cambrian Hunan