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chinese Science Bulletin 2002年第13期47卷 1119-1124页

作者： CHU Xuelei, SUN Min & ZHOU Meifuinstitute of geology and geophysics, chinese academy of sciences, beijing 100029, china Key Laboratory of Mineral Resources, institute of geology and geophysics, chinese academy of sciences, beijing 100101, china Department institute of geology and geophysics Chinese Academy of Sciences Beijing China Key Laboratory of Mineral Resources Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Department of Earth sciences The University of Hong Kong Hong Kong China

By comparing PGE patterns of sulfide ores with that of basic-ultrabasic dikes occurring in the Dajing Cu-polymetallic deposit, we discover that there are similar positive slopes between the basic-ultrabasic dikes and the black ores composed mainly of sphalerite and galena, reflecting affinity of their source. The PGE patterns of the yellow ores composed basically of chalcopyrite, arsenopyrite and pyrite are actually different. One is close to the pattern of the mantle 1herzolite, and others resemble the pattern of the basic rocks. However, the concentrations of Ru are higher in the yellow ores, reflecting that sulfur attains or approaches saturation in their parent magma. The PGE characteristics of ores and dikes show that the magmas derived from the deep of crust and the metallogenic elements were supplied mainly by growth material of the crust. In addition, the mantle-derived magma also offered some elements.

关键词： Da Hinggan area polymetallic deposit PGE pattern hypomagma.

^(40)Ar-^(39)Ar thermochronology of two ductile shear zones from Yiwulüshan,West Liaoning Region: Age constraints on the Mesozoic tectonic events

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chinese Science Bulletin 2002年第13期47卷 1113-1118页

作者： ZHANG Xiaohui, LI Tiesheng & PU ZhipingResearch Center of Mineral Resources Exploration, institute of geology and geophysics, chinese academy of sciences, beijing 100101, china Guangzhou institute of Geochemistry, chinese academy of sciences, Guangzhou 51 Research Center of Mineral Resources Exploration Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Guangzhou institute of Geochemistry Chinese Academy of Sciences Guangzhou China

Two ductile shear zones trending EW and NNE respectively not only controlled the tectonic framework of the northern North china, but also constrained the geody-namic background for gold mineralization in this region. Field observations and microstructural analyses reveal that the EW trending ductile shear zones are mainly contributed to dextral compressional deformation resulting from top-to-the-southeast oblique thrust shearing, whereas the NNE trending ones are genetically related to sinistral strike-slip and extensional faulting. One sample from the former yielded an 40Ar-39Ar plateau age of (219±4) Ma (Bi) and two samples from the latter gave 40Ar-39Ar plateau ages of (116± 2) Ma (Bi) and (127±3) Ma (Bi). These ages provide constraints on the top-to-the-southeast oblique thrusting event occurring in Late Triassic and the sinistral extensional and strike-slip faulting event which occurred in Early Cretaceous.

关键词： 40Ar-39Ar age biotite ductile shear zone West Liaoning Region.

Mineralization episode of porphyry copper deposits in the Jinshajiang-Red River mineralization belt: Re-Os dating

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Science china Earth sciences 2005年第2期48卷 192-198页

作者： WANG Denghong, QU Wenjun, LI Zhiwei, YIN Hanlong4 & CHEN Yuchuan institute of Mineral Resources, chinese academy of Geological sciences, beijing 100037, china National Center of Rock and Mineral Analysis, chinese academy of Geological sciences, beijing 100037, china Resource Assessment Center of Yunnan, Kunming 650011, china institute of geology and geophysics, chinese academy of sciences, beijing 100101, china chinese academy of Geological sciences, beijing 100037, china institute of Mineral Resources Chinese Academy of Geological Sciences Beijing China National Center of Rock and Mineral Analysis Chinese Academy of Geological Sciences Beijing China Resource Assessment Center of Yunnan Kunming China institute of geology and geophysics Chinese Academy of Sciences Beijing China chinese academy of Geological sciences Beijing China

Re-Os isotopic dating for the molybdenites from the porphyry copper deposits of the Jinshajiang-Red River mineralization belt in Yunnan Province yields isochron ages of 33.9±1.1 Ma for the Machangqing deposit and 34.4±0.5 Ma for the Tongchang deposit. This result shows that both the Machangqing and the Tongchang porphyry Cu-Mo deposits from two different ore-fields formed simultaneously. This new data and the published Re-Os model ages of molybdenite (35.4 Ma, 35.9 Ma, 36.2 Ma) of the Yulong porphyry copper deposit in Tibet, which is located in the same Jinshajiang-Red River mineralization belt as the Machangqing deposit and the Tongchang deposit, suggest that these three Cenozoic porphyry copper deposits in the Jinshajiang-Red River mineralization belt were contemporary for their mineralization episode. That is to say, even their present locality is far away and nearly iso-distantly distributed, these three porphyry Cu(Mo) deposits belong to the same mineralization episode at the end of Eocene.

关键词： Re-Os isotopic dating, porphyry Cu deposits, Cenozoic, mineralization episode.

^(40)Ar-^(39)Ar ages of the Louzidian-Dachengzi ductile shear zone near Chifeng,Inner Mongolia and their tectonic significance

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chinese Science Bulletin 2002年第15期47卷 1292-1297页

作者： ZHANG Xiaohui, LI Tiesheng, PU Zhiping & WANG HuiResearch Center for Mineral Resources Exploration, institute of geology and geophysics, chinese academy of sciences, beijing 100101, china Guangzhou institute of Geochemistry, chinese academy of sciences, G Research Center for Mineral Resources Exploration Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Guangzhou institute of Geochemistry Chinese Academy of Sciences Guangzhou China

The Louzidian normal fault occurs as the eastern detachment fault of the Kalaqin metamorphic core complex. Field observations and microstructural analyses reveal that the Louzidian-Dachengzi ductile shear zone developed in its lower-plate was genetically related to sinistral strike-slips and extensional faulting. Two samples from this ductile shear zone yield 40Ar-39Ar plateau ages of 133 Ma (Bi) and 126 Ma (Kp), which are concordant with their isochron ages. The plateau age of 133 Ma (Bi) records the formation age of the ductile shear zone. The inconsistent relationship between the earlier strike-slip ductile shear zone and the later normal fault makes the Kalaqin Quasi-metamorphic core complex distinctive from Cordil-leran nietamorphic core complex. These ages provide important geochronological data for putting constraints on the formation age and genesis of such ductile shear zones.

关键词： 40Ar-39Ar age Sinistral strike-slip Louzidian-Dachengzi ductile shear zone Metamorphic core complex.

S-wave velocity and Poisson's ratio structure of crust in Yunnan and its implication

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Science china Earth sciences 2005年第2期48卷 210-218页

作者： HU Jiafu, SU Youjin, ZHU Xiongguan & CHEN Yun Geophysical Department of Yunnan University, Kunming 650091, china Seismological Bureau of Yunnan Province, Kunming 650041, china institute of geology and geophysics, chinese academy of sciences, beijing 100101, china Geophysical Department of Yunnan University Kunming China Seismological Bureau of Yunnan Province Kunming China institute of geology and geophysics Chinese Academy of Sciences Beijing China

Receiver function of body wave under the 23 stations in Yunnan was extracted from 3-component broadband digital recording of teleseismic event. Thus, the S-wave velocity structure and distribution characteristics of Poisson's ratio in crust of Yunnan are obtained by inversion. The results show that the crustal thickness is gradually thinned from north to south. The crustal thickness in Zhongdian of northwest reaches as many as 62.0 km and the one in Jinghong of further south end is only 30.2 km. What should be especially noted is that there exists a Moho upheaval running in NS in the Chuxiong region and a Moho concave is generally parallel to it in Dongchuan. In addition, there exists an obvious transversal inhomogeneity for the S-wave velocity structure in upper mantle and crust in the Yunnan region. The low velocity layer exists not only in 10.0-15.0 km in upper crust in some regions, but also in 30.0-40.0 km in lower crust. Generally, the Poisson's ratio is on the high side, however it has a better corresponding relation to the crustal velocity structure. An obvious block distribution feature is still shown on such a high background of Poisson's ratio. It is discovered by synthetically analyzing the velocity structure and Poisson's ratio distribution that there are high Poisson's ratio and complicated crust-mantle velocity structure feature in the Sichuan-Yunnan Diamond Block with Xiaojiang fault to be the east boundary and Yulong Snow Mountain fault to be the west boundary besides the frequent seismicity. This feature differs obviously from that of surrounding areas, which would provide geophysical evidence to deeply study the eastwardly flowage of lithospheric substances in the Qinghai-Tibet Plateau.

关键词： Yunnan, S-wave velocity, Poisson's ratio, Sichuan-Yunnan Diamond Block.

Revision of the high-degree Gauss coefficients in the IGRF 1945-1955 models by using natural orthogonal component analysis

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Revision of the high-degree Gauss coefficients in the IGRF 1...

中国科学院地质与地球物理研究所2002学术年会

作者： Wen-Yao Xu institute of geology and geophysics,chinese academy of sciences,beijing,100101,china

The high-degree Gauss coefficients(n≥7) in the IGRF models for 1945-1955 exhibit some unusual and unreliable behaviors in comparison with the models for other *** this paper the method of Natural Orthogonal Components(NOC) is used to revise these *** obtained result shows that the main geomagnetic field can be approximated very well by the first a few NOC eigen *** high-degree Gauss coefficients(n≥7) are deduced for each of IGRF models using the first 6 eigen modes and low-degree Gauss coefficients(n≤6).The deduced high-degree coefficients are in very good agreement with the original ones for all models except those for 1945,1950 and *** comparison with the unusual behaviors in the IGRF1945-1955 models,the deduced high-degree coefficients for these models exhibit fairly smooth ***,the magnetic energy and magnetic flux calculated by the revised Gauss coefficients show more continuous secular variations and consistent characteristics.

关键词： NOC IGRF model eigen mode

Fluid inclusion and stable isotope constraints on the genesis of the Mazhuangshan gold deposit,eastern Tianshan Mountains of china.

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Fluid inclusion and stable isotope constraints on the genesi...

中国科学院地质与地球物理研究所2002学术年会

作者： LI XinJun and LIU Wei institute of geology and geophysics,chinese academy of sciences,beijing 100101,china

On the basis of investigation of ore deposit geology,petrography and microthermometry,this study performed analyses of H- and O-isotope compositions and gas compositions of sulfide- and quartz-hosted fluid inclusions,and S- and Pb-isotope compositions of sulfide separates from the Mazhuangshan gold deposit,eastern Tianshan Mountains of *** ore-forming fluid is characterized by medium temperature,medium to low salinities,and is rich in CO and Na,K,Cl *** with gangue quartz-hosted fluid inclusions,the sulfide-hosted ones are richer in gaseous species CO,CO,HS and O *** other gasous components,except for CO,do not exhibit linear correlations with ***δD andδO values of inclusion water from quartz vary from -93‰to -106‰,and from 1.1‰to 2.4‰,***δS values are centered around 4.5‰-6.5‰.Integrated isotopic data point to two major contributions to the mineralizing fluid that include the magmatic fluid and the meteoric-derived *** Pb/Pb,Pb/Pb,and Pb/Pb values of pyrite range from 17.896 to 18.449,from 15.256 to 15.760,and from 37.076 to 38.711,*** show good linear correlations,with correlation coefficients greater than *** characteristics indicate multi-sources for the metallic materials that range from the crust to the *** summary,fluid mixing is the main mechanism for the formation of the Mazhuanshan gold *** magmatic fluid released from the magma intrusion mix with meteoric-derived groundwater to generate the ore-forming *** ore-forming fluid circulates crustal rocks and extract metallogenetic materials therein.

关键词： Fluid inclusion Isotope Fluid mixing Mazhuangshan gold deposit

GLOBAL HEAT FLOW SIMULATION BASED ON KINEMATIC MODEL OF MANTLE FLOW

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GLOBAL HEAT FLOW SIMULATION BASED ON KINEMATIC MODEL OF MANT...

中国科学院地质与地球物理研究所2002学术年会

作者： Zheng-Ren YE Jian WANG institute of geology and geophysics,chinese academy of sciences,beijing 100101,china

The global heat flow is the surface representation of thermal processes within the earth’s *** long-wavelength pattern of observed heat flow closely resembles the plate tectonics and its most prominent feature is higher values along ocean ridge ***,to determine the thermal state of the earth’s mantle,the heat transfer problem and the mantle convection problem have to be solved simultaneously since they are coupled with each other. However,the development of global seismic tomography provide us with a possibility that,at least under certain assumptions,these problems can be decoupled from each other and solved separately. This allows us to calculate mantle flow velocities first based on the internal loading theory and then use the velocity field as the input to solve the thermal *** addition to the internal density anomalies,surface plate movements also excite mantle circulations and,under certain circumstance, they may dominate the structure of the mantle flow. In this study,using a kinematic model of mantle convection and heat transfer,we investigated the underlying processes that generated the observed global heat *** from the density anomalies and the coupling from the overlying plates are treated as the mantle flow driving force. Both advection and conduction heat transfers are included in the energy *** show that calculated depth derivatives of the near-surface temperature are closely correlated to the observed surface heat flow *** heat flow values around mid-ocean ridge systems can be reproduced very *** predicted average temperature as a function of depth reveals that there are two thermal boundary layers,one is close to the surface and another is close to the core-mantle *** rest of the mantle is nearly ***,in most of the mantle,advection dominates the heat transfer,the conductive heat transfer is still locally important in the boundary layers and plays an import

关键词： heat flow mantle flow plate motion density anomaly tomography

Epicenter Location by Abnormal ULF Electromagnetic Emissions

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Epicenter Location by Abnormal ULF Electromagnetic Emissions

中国科学院地质与地球物理研究所2002学术年会

作者： Aimin Du Qinghua Huang Shaofeng Yang institute of geology and geophysics,chinese academy of sciences,beijing 100101,china

The epicenter location before earthquake is very *** investigated the characteristics of the ULF electromagnetic emissions,which were observed by an east-west chain at Kashi,Anxi,and beijing stations before the M=7.1 Hetian earthquake,Xingjiang,china, November 19,*** define the polarization angle as the angle between the east direction of the geomagnetic field and the major axis of the polarization ellipse,which is obtained by the filtered data of two horizontal *** source of ULF electromagnetic emissions before earthquake is most probably coming from the direction perpendicularly to the polarization major axis of earthquake related *** located the source as the cross of two source directions that were obtained at Kashi and Anxi station on November 18,*** estimated source is consistent with the epicenter of the Hetian event.

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Paleomagnetism of early Paleozoic volcanic rocks from the Beishan area,Gansu of northwest china:Preliminary insight into early Paleozoic kinemics of the Beishan terrane

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Paleomagnetism of early Paleozoic volcanic rocks from the Be...

中国科学院地质与地球物理研究所2002学术年会

作者： HUANG Baochun,WANG Yongcheng,ZHU Rixiang & ZHANG Fuqin institute of geology and geophysics,chinese academy of sciences.beijing 100101,china

We report rock magnetic and paleomagnetic results for Middle Silurian Gongpoquan and Middle Ordovician Huaniushan volcanic samples collected from the Mazongshan and Hongliuyuan areas of Gansu Province,northwest *** results indicate that the main magnetic mineral of the Gongpoquan and Huaniushan volcanic rock is magnetite,and it may remain characteristic remanent magnetization acquired at the time of formation of the rocks. However,with the exception of samples from site go20,most of Middle Ordovician Huaniushan volcanic samples have a very weak nature remanent magnetization,and generally show an erratic demagnetization behavior,which does not allow isolation of characteristic remanent magnetizations from these *** of paleomagnetic results obtained from the Beishan area of Gansu with Paleozoic apparent polar wander paths for Tarim and Siberia suggests that the Beishan tarrane,the southern part of the Beishan area of Gansu beyond the Mingshui-Shipanjin-Xiaohuangshan zone,and adjacent Tarim block and Siberia plate could not have been connected in their present configuration by the Middle Silurian *** the other hand,we infer that the early Paleozoic Mingshui-Shipanjin-Xiaohuangshan oceanic basin may open from west to east during period from the Ordovician to Silurian,and the post-Middle Silurian closing of this oceanic basin may result from a progressed eastward scissor-like rotation.

关键词： Beishan area of Gansu Early Paleozoic rock magnetism and paleomagnetism