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The tectonic setting and geochemical characteristics of metamorphic basement in the southwest of the Yangtze Plate

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chinese science Bulletin 1999年第S2期44卷 266-268页

作者： zhang Hongxiang~1, LIU Congqiang~2. HUANG Zhilong~2.and XU Zhifang~1 1. institute of Geophysics,{2.s, Beijing 100101, China 2. institute of geochemistry,{2.s, guiyang 550002. China institute of Geophysics Chinese Academy of Sciences Beijing 100101 China institute of geochemistry Chinese Academy of Sciences Guiyang 550002 China

THE Dahongshan Group (in short DG) and its basement Dibadu Formation (in short DF) in the southeastof the Yangtze Plate are one of the oldest geological units in the Yangtze Plate. It is established in thisnote by means of geochemistry that the system of trench-arc-basin was formed by the subducting at thesouthwestern boundary of the Yangtze Plate in Lower Proterozoic Subera. And the existence of enrichedmantle EMI is argued by the way of trace elements geochemistry. 1 Regional geological setting There is a unit of the typical two-layer structure platform in the southwest of the Yangtze Plate. Themetamorphic basement of this platform is made up of Suberathem Dahongshan Group and SuberathemKunyang Group. Above them, there have covered expansive continental deposits from Mesozoic. The primary rocks of DG are composed of deposited limestone, sandstone and basalts. The basalts represent

关键词： Dahongshan Group(DG) Dibadu Formation(DF) tectonic geochemistry.

New technique to control in situ oxygen fugacity in water-free high-pressure system──Using Cu-O as an example

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chinese science Bulletin 1998年第16期43卷 1353-1358页

作者： LI Heping 1, XIE Hongsen 1, GUO Jie 1, zhang Yueming 1,XU Zuming 1 and XU Ji’an 2.1. {2. of geochemistry, chinese academy of sciences, guiyang 550002. China 2. {2. of Earth sciences, Taiwan 1152., China institute of geochemistry Chinese Academy of Sciences Guiyang China institute of Earth sciences Taiwan China

Through inserting a solid oxygen-specific electrolyte (YSZ) inside and exerting an electrical power of direct current outside between the sample and oxygen reservoir (an solid oxygen buffer), oxygen was driven by the power from the cathodic electrode area into the positive electrode area at high temperature and high pressure. In this way, the oxygen fugacity in the sample was in situ controlled independently of temperature and pressure. By using Cu-O system as an example, this technique was proved to be successful.

关键词： in situ control of oxygen fugacity water-free system high temperature and high pressure.

Dynamic processes of ore-forming fluid and the localization of orebody: case study on the sediment-hosted gold deposits of southwestern Guizhou, China

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chinese science Bulletin 1999年第S2期44卷 263-265页

作者： zhang Chengbo and zhang Zheru {2. of geochemistry, chinese academy of sciences, guiyang 550002. China institute of geochemistry Chinese Academy of Sciences Guiyang 550002 China

1 Geological setting and occurrence features of the sediment-hosted gold deposits OVER 100 sediment-hosted gold deposits and occurrences of southwestern Guizhou lie near the sonthemedge of the Yangtze craton, which is composed of crystalline rocks of Proterozoic age, overlain mainly byPaleozoic and Lower to Middle Triassic shallow-marine platform and reef facies carbonates that gradesouthward and eastward into a thick section of interbedded siltstones and turbidite sandstones. Clasticdeposits were from the Yunkai Old Land and the Jiangnan Old Land respectively. The rocks were foldedand faulted during the Yanshanian orogeny, 190-65 ma ago. Mineral deposits were mainly located inthe breccia horizon at the base of the Longtan Formation of Upper Permian, underlain by the massive graylimestone of Lower Permian with a karst unconformity, and the high-angle fault zones in the Triassicargillaceous limestone interlayered with shale, arkose, and fine-grained turbidite sandstone. No

关键词： sediment-hosted gold deposits fossil hydrothermal system mathematical model.

Physical mechanisms of plant roots affecting weathering and leaching of loess soil

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science China Earth sciences 2006年第9期49卷 1002-1008页

作者： LI Yong1,2. zhang Qingwen1,2. WAN Guojiang3, HUANG Ronggui3, PIAO Hechun3, BAI Lingyu2.& LI Lu2.1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, {2. of Soil and Water Conservation, chinese academy of sciences, Yangling 712.00, China 2. {2. of Agro-Environment and Sustainable Development, chinese academy of Agricultural sciences, Beijing 100081, China 3. {2. of geochemistry, chinese academy of sciences, guiyang {12. China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water Conservation Chinese Academy of Sciences Yangling China institute of Agro-Environment and Sustainable Development Chinese Academy of Agricultural Sciences Beijing China institute of geochemistry Chinese Academy of Sciences Guiyang China

Plant roots have potential impacts on soil mineral weathering and *** objective is to understand the physical mechanisms of plant roots affecting weathering andleaching of loess soil. Root densities were measured through the method of a large-size dug profile,and transport fluxes of soil elements were determined using an undisturbed monolith soilinfiltration device on the hilly and gully regions of the chinese Loess Plateau. The results showthat the improvement effects of soil environment by plant roots are mainly controlled by the densityand weight of the fibrous roots with the diameters less than 1 mm. Plant roots have the strongereffects on soil physical properties than chemical properties. The principal components analysis(PCA) indicates that soil physical properties by plant roots account for 56.7% of variations in soilenvironment whereas soil chemical properties and pH contribute about 2..2. of the soil *** roles of plant roots in controlling soil weathering and leaching increased in the followingorder: infiltration enhancement > increase of bio-active substance > stabilization of soilstructure. The effects of plant roots on soil mineral weathering and leaching can be quantifiedusing the multiple regression models with the high prediction accuracies developed in this study.

关键词： plant roots, soil weathering and leaching rates, soil environment field, principal components analysis (PCA), chinese Loess Plateau.

Gold occurrence mechanism of fine disseminated gold deposits

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chinese science Bulletin 1999年第S2期44卷 18-20页

作者： WANG Xiaochun and zhang Zheru institute of {2., chinese academy of sciences, guiyang 550002. China institute of geochemistry Chinese Academy of Sciences Guiyang 550002 China

THE fine disseminated gold deposits are widely distributed in the southwestern China and western UnitedStates. They have a mineral association of pyrite, arsenopyrite, marcasite, realgar, orpiment, stibnite,cinnabar, quartz, calcite and barite, and an element association of gold, arsenic, antimony, mercury,thallium and barium. Gold occurs as disseminated and in small size. This note aims to discuss the disseminated nature and micron size of the gold.

关键词： gold mechanism fine disseminated gold deposit.

A sodium metasomatism process in Xiaoqingshan lode-copper deposit in Kangdian region, southwestern China

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chinese science Bulletin 1999年第S2期44卷 176-178页

作者： WANG Jiangzhen~1, ZHEN Minghua~2.and LU Yan~2.1. lnstitute of geochemistry,{2.s, guiyang 550002. China 2. Chengdu institute of Technology, Chengdu 610059, China institute of geochemistry Chinese Academy of Sciences Guiyang 550002 China Chengdu institute of Technology Chengdu 610059 China

THE Kangdian region is a middle Proterozoic continental rift basin that extends between longitudes 101°30’and 103°2.’. There are a series of sedimentary strata, named Xiaoqingshan Formation, Yinmin Forma- tion, and Luoxue Formation. The strata were metamorphosed and deformed in Jinning tectonic event between approximately 850 and 750 ma. There are many lode-copper deposits in the Kangdian region. Xiaoqingshan is a typical one among of them. The orebodies of the deposit occurs in veins and the hostrocks of the deposit are sericite-phyllite and sericite-slate. The deposit is characterized by large-scale pervasive sodium metasomatism （PSM）. It has been identified that albite replaced sericite and chlorite of the original rocks during the *** a result, the pelites were transformed into albitolite, which consists of albite totally. mass balancecalculations show that the PSM process involved addition of large amount of Na2./sub>O and SiO2./sub>, and

关键词： sodium metasomatism copper deposit southwestern China.

Some advancements in measurements of physical parameters of earth's material at high temperature and ultrahigh pressure

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chinese science Bulletin 1997年第21期42卷 1807-1810页

作者： XIE Hongsen, zhang Yueming, GUO Jie, XU Ji’an, SONG maoshuang, XU Yousheng and HOU Wei1. {2. of geochemistry, chinese academy of sciences, guiyang 550002. China 2. {2. of Earth science, Academia Sinica, Taipei, China institute of geochemistry Chinese Academy of Sciences Guiyang China institute of Earth science Academia Sinica Taipei China

IT is very important to measure physical parameters of minerals, rocks, melts and fluids athigh pressure and high temperature. The data from these experiments can provide materialsfor explanation of geophysical observations on large scale, and information of geochemicalfield. Therefore, we set up measurement methods on elastic wave velocity, electrical conduc-tivity and differential thermal analysis in YJ-3000 ton press fitted with a wedge-type

关键词： physical parameters earth’s material high temperature and nltrahigh pressure.

Oxygen isotopic (^(17)O-^(18)O) heterogeneity in Archaean continental nucleus, North China Craton

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chinese science Bulletin 1999年第24期44卷 2267-2269页

作者： LIU Jianzhong, zhang Fuqin, LI Chunlai and WANG Shijie institute of {2. , chinese academy of sciences , guiyang 550002., China institute of Geophysics , chinese academy of sciences , Beijing 100101 , China institute of geochemistry Chinese Academy of Sciences Guiyang China institute of Geophysics Chinese Academy of Sciences Beijing China

The oxygen isotopic data for amphibolites from Archaean continental nucleus, North China Craton indicate that ( i ) the evolving lines structured by the data are parallel to the geoselenic evolving line, which means that the parent materials of these continental nucleus o-riginated from solar matter; ( ii ) different intercepts for these evolving lines manifest that oxy-

关键词： North China Craton oxygen isotope (I7O-18O ) heterogeneity.

Environmental records of lacustrine sediments in different time scales:Sediment grain size as an example

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science China Earth sciences 2004年第10期47卷 954-960页

作者： CHEN Jing’an1, WAN Guojiang1, David Dian zhang2. zhang Feng1 & HUANG Ronggui1 1. State Key Laboratory of Environmental {2., institute of {2., chinese academy of sciences, guiyang 550002. China 2. Department of Geography and Geology, University of Hong Kong, Pokfulam Road, Hong Kong, China State Key Laboratory of Environmental geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang China Department of Geography and Geology University of Hong Kong Hong Kong China

Sediment grain size is a conventional proxy of climatic changes. Larger sediment grain size is often interpreted to indicate dry climate during lower lake level while smaller sedi- ment grain size implies wet climate during higher lake level. Through detailed study on sediment grain sizes in Lake Erhai and Lake Chenghai, this paper reveals the different indication signifi- cances of sediment grain sizes in different time scales, different resolution investigations. For long time-scale and low resolution (102. or 103a) studies, larger sediment grain size indicates lower lake level, smaller lake area and drier climate while smaller sediment grain size indicates higher lake level, larger lake area and wetter climate. For short time-scale and high resolution (a or 10a) studies, larger sediment grain size reflects more rainfall and wetter climate while smaller sediment grain size reflects less rainfall and drier climate. Environmental information revealed by lacustrine sediment records is often different in different time scales because of the variance of sedimentation resolution, sampling resolution and dating precision. Therefore, paleoclimate im- plications of environmental proxies in long time-scale and low resolution investigations could not be mechanically applied to short time-scale and high resolution studies. Only after synthetically analyzing the influence manner and extent of all factors on the sediment records in different time scales, can credible conclusions be obtained.

关键词： lacustrine sediment, environmental record, grain size, time scale.