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Chronological and geochemical studies of granite and enclave in Baimashan pluton, Hunan, south china

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science china Earth sciences 2007年第11期50卷 1606-1627页

作者： CHEN WeiFeng1, CHEN PeiRong1, HUANG HongYe2, DING Xing1,3 & sUN Tao1 1 state Key Laboratory of Mineral Deposit Research, Department of Earth sciences, Nanjing University, Nanjing 210093, china 2 Research institute No.230, CNNC, Changsha 4.0011, china 3 guangzhou institute of Geochemistry, chinese academy of sciences, guangzhou 51064., china 1. state Key Laboratory of Mineral Deposit Research Department of Earth Sciences Nanjing University Nanjing 210093 China 2. Research institute No.230 CNNC Changsha 410011 China 3. guangzhou institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China

Zircon LA-ICP-Ms U-Pb dating reveals that the Baimashan Pluton is composed mainly of late Indosinian (204.5±2.8 Ma-209.2±3.8 Ma) biotite granodiorites/monzonitic granites (LIGs) and early Yanshanian (176.7±1.7 Ma) two-micas monzonitic granites (EYGs), and the coeval (203.2±4.5 Ma-205.1±3.9 Ma) mafic microgranular enclaves (MMEs) are generally found in the former. In addition, the ages of cores within zircons from LIGs and MMEs ranging from 221.4.4.0 Ma to 226.5±4.1Ma provide evidence of multistage magma intrusion during Indosinian in the study area. Measured 3010±20.6 Ma of inherited zircon age suggests that there may be recycling Archaean curstal material in existence in this area. LIGs and EYGs share some similar geochemical features: subalkaline and peraluminous granites, enrichment of Th, U, K, Ta, Zr, Hf and LREE but depletion of Ba, Nb, P, Ti and Eu, low εNd(t) values but high (87sr/86sr)i ratios, and old T2DM (ca. 1.9-2.0 Ga). The behaviors of incompatible elements and REE are mainly dominated by fractional crystallization of plagioclase, K-feldspar, ilmenite and apatite, but that of sr isotope mainly controlled by EC-AFC. They are crust-sourced and derived from partial melting of paleo-Proterozoic metagreywackes and related to biotite dehydration melting. LIGs are formed in post-collisional tectonic setting as crustal local extension and thinning during late Indosinian. But EYGs may be evolved products of congeneric granitic magma with LIGs formed in late Indoinian, which were emplaced again when crust underwent extensive thinning and extension in post-orogenic tectonic setting during Yanshanian in sC after undergoing EC-AFC. MMEs should be cognate enclaves and derived from liquid immiscibility of host magma.

关键词： granite,mafic microgranular enclave,zircon LA-ICP-Ms dating,lithogenesis,EC-AFC

Zircon sHRIMP U-Pb geochronology and petrogenesis of the plagiogranites from the Lagkor Lake ophiolite,Gerze,Tibet,china

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chinese science Bulletin 2007年第5期52卷 651-659页

作者： ZHANG YuXiu1,2, ZHANG KaiJun1,3, LI Bing1,2, WANG Yang1,2, WEI QingGuo1,2 & TANG XianChun1,2 1 Key Laboratory of Marginal sea Geology, guangzhou institute of Geochemistry, chinese academy of sciences,{4., china 2 Graduate University, chinese academy of sciences, Beijing 100039, china 3 Department of Earth sciences, Nanjing University, Nanjing 210093, china Key Laboratory of Marginal sea Geology Guangzhou Institute of GeochemistryChinese Academy of Sciences Guangzhou 510640 China

地关系与 petrographical 一起， petrological ，和 geochemicalcharacteristics ，和锆石人口，显示从在 Bangong-Nujiang 缝术地区的 Lagkor Lakeophiolite 的 plagiogranites (～ Gerze 县的 20 km 南方，中央西藏，中国)，由在海洋的外壳的运输期间的可锻的砍源于含水的斑粝岩的 anatexis 。因此，这种 plagiogranite 比传播海洋的外壳晚对或很少同时代。锆石虾 166 ±使 2.5 妈变老因为 plagiogranites 显示海洋的盆在中间的侏罗记在 Bangong-Nujiang 地区的西方的部分存在。

关键词：西藏改则县拉果错湖泊蛇绿岩斜长花岗岩锆sHRIMP U-Pb地质年代岩石成因

geochemical constraints from hydrothermal fluid inclusions of altered deformation zone type Au(Ag)deposits in Yunkai area, south china

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chinese science Bulletin 1999年第S2期44卷 230-232页

作者： WANG Zuwei~1, ZHANG Haihua~2, YAO Dongliang~2 and ZHOU Yongzhang~3 1. Department of Geography, Tianjin Normal University, Tianjin 300071, china 2. guangzhou institute of Geochemistry, chinese {4. of sciences, guangzhou 51064., china 3. Department of Earth sciences, Zhongshan University, guangzhou 510275, china eeszhou@*** Department of Geography Tianjin Normal University Tianjin 300071 China guangzhou institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China Department of Earth sciences Zhongshan University Guangzhou 510275 China

THE altered deformation zone type Au (Ag) deposits share an important part from the precious metallicore deposits in the Yunkai area, south china. Their formation is a history of poly-stage evolution. Pre- liminary source strata, Calidoniam metamorphism, Indosinian-Yanshanian ductile shear deformation andassociated hydrotheraml alteration all play certain roles in the history. This note discusses the geochemical conditional of the hydrothermal fluids during mineralization. Two representative ore deposits, the Pangxidong Ag(Au) deposit and Hetai Au deposits are selectedfor this study. They are hosted in altered ductile shear zones. Wall-rock hydrothermal alteration is bothspatially and temporally associated with the development of the ductile shear system. silicification occurred throughout the whole alteration process. There are three groups of quartz: thepredeformational quartz, the early stage hydrothermal quartz, and the late stage hydrothermal quartz asso-

关键词： precious metallic deposit fluid inclusions mineralizing fluid south china.

geochemical behavior of elements at fossil sea floor water/sediment interface

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chinese science Bulletin 1999年第S2期44卷 232-233页

作者： ZHANG Haihua~1, XIA Yu~1, WANG Zuwei~2 and ZHOU Yongzhang~3 1. guangzhou institute of Geochemistry, chinese academy of science,{4., china 2. Department of Geography, Tianjin Normal University, Tianjin 300071, china 3. Department of Earth sciences, Zhongshan University, guangzhou 510275, china guangzhou institute of Geochemistry Chinese Academy of Science Guangzhou 510640 China Department of Geography Tianjin Normal University Tianjin 300071 China Department of Earth sciences Zhongshan University Guangzhou 510275 China

THIs note deals with the geochemical behavior of elements near the water/sediment interface of a fossil seafloor. The Nandan-Hechi basin, located in northwest Guangxi, southern china, is selected for exemplified study. It is an elongated basin, and developed on a Caledonian basement. Its Devonian strata hosthydrtothermally sedimentary formations, and are typical of the intra-platformal basin facies sediments oversouthern china. A steady sedimentary sequence may be observed, commonly going from carboniferouspelite at bottom, upward through bedded chert, thickly banded argillaceous limestone, thinly bandedsiliceous limestone and small lensiod argillaceous limestone in the middle, to coarse lensoid siliceousand/or argillaceous limestone at the top. The chert and some argillaceous limestone are related to hydrothermally sedimentary origin. The present study focuses on the lensoid argillaceous limestone formation. This formation contains the following characteristic sedimentary structures: small lensoid structure,vermiform structure, wave-shaped banded structure, massive structure, white framboid structure, andcage netting structure.

关键词： water/sediment interface sedimentation periodicity sedimentary geochemistry basin.

Thermodynamic Modelling of Ore-Forming Mechanism of the Changkeng Gold-silver Deposits in Guangdong Province

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Acta Geologica sinica(English Edition) 1997年第4期71卷 433-445页

作者： Zhang sheng, Li Tongjin and Wang Liankuiguangzhou institute of Geochemistry, chinese academy of sciencesWushan,{4. guangzhou institute of Geochemistry Chinese Academy of Sciences Wushan Guangzhou 510640 [?]Zhang sheng Born in 1967 graduated from china University of Geosciences (Wuhan) in 1989 and acquired the master's and doctor's degrees in chinese academy of sciences (CAs) and Guangdong institute of Geochemistry CAS in 1992 and 1996 successively. He is now engaged in studies of metallic ore deposits geochemical thermodynamics and experimental geochemistry.

The Changkeng gold-silver deposits consist of a sediment-hosted, disseminated gold deposit and a replacement-type silver deposit. The mineralizations of gold and silver are zoned and closely related to the silicification of carbonate and clastic rocks, so that siliceous ores dominate in the deposit. The mineralizing temperature ranges mainly from 300 to 170℃, and K+, Na+, Ca2+, Mg2+, and Cl- are the major ions in the ore-forming fluid. Calculations of distribution of metal complexes show that gold is mainly transported by hydrosulphide complexes, but chloride complexes of silver, iron, lead, and zinc, which are transformed into hydroxyl and hydrosulphide complexes under neutral to weak-alkaline circumstances in the late stage, predominate in the ore-forming solutions. Water-rock interaction is confirmed to be the effective mechanism for the formation of silver ores by computer modelling of reaction of hydrothermal solution with carbonate rocks. The solubility analyses demonstrate that the precipitation of gold and silver-bearing minerals taking place under weak-acid conditions and near-neutral to weak-alkaline conditions, respectively, is the main or favourable factor for the ore zonation and separation between gold and silver.

关键词： computer modelling transport form of element water-rock interaction mineral precipitation gold-silver deposit Guangdong province

Proterozoic copper metaliogenic framework and geochemistry steep zone in central Yunnan Province

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chinese science Bulletin 1999年第S2期44卷 163-164页

作者： CHANG Xiangyang, ZHU Bingquan and DONG Yunpeng guangzhou institute of Geochemistry, chinese academy of sciences, guangzhou, 51064., china

THE wildly horizontal and vertical chemical heterogeneties, which result from the inchoate core-mantledifferentiation of the globe and the spatio-temporal difference of various regions in the globe, bring on themantle and crust from different landmass and oceans with markedly elemental and isotopic *** these signatures could be used to differentiate the attribute from various landmass or oceans andrecover the scent of kinematics and chemical geodynamics process. It is a quantificational method compared with the division by geotectonics facies and paleontologic fauna. Based on the geochemistry mapping of elements and multi-isotopic systematics of rocks derived frommantle and crust and combined with the studies on geophysical tomographic image, four type geochemicalprovinces can be distinguished. They are: (i) the Pacific (such as N-Pacific, N-Atlantic, the

关键词： Proterozoic copper metallogenesis geochemical steep zone Yunnan.

Metamorphosed mafic rocks with N-type MORE geochemical features in Hainan Island-Remnants of the Paleo-Tethys Oceanic Crust?

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chinese science Bulletin 2000年第10期45卷 956-961页

作者： LI Xianhua, ZHOU Hanwen, DING shijiang, LEE Chi-yu, ZHANG Renjie, ZHANG Yeming & GE Wenchun1. guangzhou institute of Geochemistry, chinese academy of sciences,{4., china 2. Hainan Geological survey, Haikou 570206, china 3. Department of Geology, Taiwan University, Taipei 106-17, china 4. Yichang institute of Geology and Mineral Resources, chinese academy of Geological sciences, Yichang 4.3003, china

A number of metamorphosed mafic rocks occurred within the Paleozoic strata in the Chenxing and Bangxi regions at the northern side of the Changjiang-Qionghai Fault in Central Hainan Island. These metamorphosed mafic rocks are tholeiites in chemistry. They are characterized by extreme depletion of Th, Nb, Ta and LREEs, resembling the depleted N-type mid-ocean ridge basalts (MORE). Field relations suggest that the protolith of the metamorphosed mafic rocks were likely formed in Paleozoic. These metamorphosed mafic rocks with N-type MORB geochemical features were probably the remnants of the Paleo-Tethys oceanic crust.

关键词： N-type MORB metamorphosed mafic rocks element geochemistry Hainan Island.

Pool-formation and secondary change of biodegraded viscous oils:Case study of reservoir section in the ZhengjiaWangzhuang Oilfield, Jiyang Depression

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chinese science Bulletin 2004年第S1期49卷 39-49页

作者： WANG Zhenqi, PENG Ping’an, YU Chiling, LU Hong, ZOU Yanrong, ZHANG Linye & LIU Junmin state Key Laboratory of Organic Geochemistry, guangzhou institute of Geochemistry, chinese academy of sciences,{4., china Department of Earth science, Yangtze University, Jingzhou 4.4.23, china Research institute of Geology, shengli Oilfield Co. Ltd., sINOPEC, Dongying 257015, china chinese Acad sci State Key Lab Organ Geochem Guangzhou Inst Geochem Guangzhou 510640 Peoples R China Yangtze Univ Dept Earth Sci Jinzhou 434023 Peoples R China shengli Oilfeld Co Ltd Res Inst Geol SINOPEC Dongying 527015 Peoples R China

It is demonstrated by various geochemical indexes that the Zhengjia-Wangzhuang Oilfield with viscous crude oil in the Jiyang Depression has been sourced from the contribution of matured source rocks in the upper Es4. The principal cause leading to the densification of crude oils would be biodegradation, with the degradation level of crude oils being ranked as 2-8; vertically, the biodegradation level increases from the top to bottom of the oil column, with a distinctive biodegradation gradient occurring. Calculated parameters of sterane, terpane and methyl-phenanthrene have indicated that the source-rock’s maturity of crude oils and asphaltic sands ranges from 0.7 to 0.9, and based on the calculation of Easy Ro model, the temperature of hydrocarbon generation in the source rock would be within 120-14.℃, which coincides with the measurements of reservoir inclusions. The measured homogenization temperature would represent the generation temperature of the source rock, and be fairly different from that

关键词： viscous oil biodegradation time of pool-formation time of degradation Jiyang Depression.

Lead Isotopic steep-Dipping Zone and　Mineralization—An Example from　Mineral Deposits Concentrated　Area in East Qinling,china

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Journal of Earth science 2000年第1期19卷 68-75页

作者： Zhang Zhengwei Zhu Bingquan guangzhou institute of Geochemistry, china academy of science,{4. Cai Keqin Deng Jun Department of Earth and Mineral Resources, china University of Geosciences, Beijing 100083 Wang Wei Qiang Lizhi Henan

Lead isotopic geochemical steep-dipping zone usually exists on inhomogeneous boundaries of earth blocks. Its crossing with the geophysical gradient zone often convergently occurs at giant deposits. Deep structures or concealed structural planes obviously have the coupling relationship with the convergent area of mineral deposits. The geochemical steep-dipping zone is usually distributed along the boundary of ancient continental blocks. Its crossing effect with geophysical gradient zone is usually presented as depression or swell of Moho discontinuity on the crossing direction with the ancient continental margin, which would lead to form deep fractures of earth crust at block margins or lead to adjustment of earth crust texture. The deep hydrothermal liquid would rise up along the structural planes to form the convergent areas of mineral deposits. For example, Luonan- Luanchuan area in east Qinling is a typical crossed area of the geochemical steepdipping zone and geophysical gradient zone. The mineral deposit belt extends along EW direction. It was controlled by the geochemical steepdipping zone equidistantly distributed along NE direction like a string of beads controlled by a gravity gradient zone in NE direction and a mantle depression slope. Along a plunging mantle syncline on EW plunging direction, from the east to the west, checkform was distributed which controls synergic crustmantle granoporphyry rocks. Therefore, a convergent mineralization area of Mo, W, Zn and Au giant deposits occurred.

关键词： lead isotopic steep-dipping zone mineralization East Qinling.