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^(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 {2. institute of geochemistry, chinese academy of sciences, {2. 51 Research Center of Mineral Resources Exploration Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China guangzhou institute of {2. 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 (2.9±4) Ma (Bi) and two samples from the latter gave 40Ar-39Ar plateau ages of (116± 2. Ma (Bi) and (12.±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.

Quasirational dynamic system

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chinese Science Bulletin 2000年第14期45卷 1277-1279页

作者： SUN Daochun & YANG Lo1. Department of Mathematics, South China Normal University, guangzhou 510631, China 2. institute of Mathematics, {2. of Mathematics and System sciences, chinese academy of sciences, Beijing 100080, China Department of Mathematics South China Normal University Guangzhou China institute of Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China

Using the iterations of quasirational mappings, the theorems on dynamic system are generalized to the quasirational dynamic system. Some different results are also obtained.

关键词： quasirational mapping dynamic system covering surface.

Oxygen and hydrogen isotopic compositions of coexistent minerals of the Tasigake alkali granite pluton,northern Xinjiang:constraints upon the cause of ^(18)O-D depletion and the ^(18)O/^(16)O exchange kinetics

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chinese Science Bulletin 1999年第12期44卷 1086-1093页

作者： LIU Wei, ZHAO Zhenhua ZHANG Fuqin Research Center of Mineral Resources Exploration, institute of Geophysics , chinese academy of sciences , Beijing 100101, China {2. institute of geochemistry, chinese academy of sciences , guangzhou 51064., China Research Center of Mineral Resource Exploration Institute of Geophysics Chinese Academy of Science Beijing China guangzhou institute of {2. Chinese Academy of Sciences Guangzhou China

Oxygen and hydrogen isotopic compositions have been determined of three coexistent mineral triplets of alkali feldspar, quartz, arfvedsonite of 11 samples collected from the Tasigake alkali granite pluton, Ulungur River region, northern Xinjiang. Isotopic exchange with meteoric water during subsolidus cooling caused strong 18O-D depletion and the remarkable nonequilibrium 18O/16O relation between coexistent minerals. 18O/16O exchange kinetic effects of the three minerals are simultaneously and consistently modelled. Exsolution and microtextural reorganization of alkali feldspar, and infiltration of water have been mutually facilitated by each other. Shallow intrusion, and circulation of meteoric water throughout the pluton cool it effectively. As a result, the "heat engine" is rapidly extinguished, and the nonequilibrium 18O/16O relation is frosen.

关键词： 18O-D depletion isotopic exchange kinetics alkali granite Ulungur.

ABUNDANCE AND DISTRIBUTION OF PLATINUM-GROUP ELEMENTS (PGE) IN PERIDOTITE FROM THE DAGZHUKA OPHIOLITE IN TIBET:IMPLICATIONS FOR MANTLE METASOMATISM

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地学前缘 2000年第S1期7卷 99-100页

作者： Xia Bing 1,2.,Yu Hengxiang 1,Mei Houjun 1,Qi Lang 2.(1 guangzhou institute of {2., chinese academy of sciences, guangzhou 51064., China 2.institute of {2., chinese academy of sciences, Guiyang 550002. China)

Information on abundance and distribution of platinum\|group elements (PGE) in peridotite from ophiolite is relevant to understand the nature and evolution of the upper mantle. The ophiolite suite outcropping along the famous suture zone of Yarlung Zangbo River, Tibet, has attracted wide attention of geologists both in China and abroad. The Dagzhuka ophiolite of in the suture zone is thought to display a complete ophiolitic sequence. The peridotite from the Dazhuka ophiolite is composed of fairly fresh or unaltered lherzolite, harzburgite and minor dunite which are the upper mantle residuum formed by 15%～35% partial melting. In this paper we have mainly studied the abundance and distribution of PGE in the harzburgites and lherzolites. The harzburgites and lherzolites preserve total PGE contents of 2. 37×10 -9 ～50 67×10 -9 respectively higher than Primitive mantle or the peridotite from some typical ophiolites and Alpine. They all have fractionated chondrite\|normalized PGE patterns with positive slopes from Ir to Pd (Fig.1), and Pd/Ir=1 13～2.40>1, Pd/Rh=2.2.～7 49>1, and Pd/Pt=0 2.～1 16 (average 0 67) higher than Primitive mantle (1 11, 2.35, 0 57) or CI\|chondrite (1 01, 2.73, 0 53). Consequently, the Dagzhuka peridotite are PGE\|enriched, but otherwise possess residual characteristics arising from a minimum of 15% partial melting. It is suggested that mantle residuum by partial melting have low total PGE contents, fractionated chondrite\|normalized PGE patterns with negative or slightly flat slopes from Ir to Pd, and Pd/Ir<1. But, the total PGE contents, chondrite\|normalized PGE patterns and Pt/Ir, Pd/Rh and Pd/Pt values of the Dagzhuka peridotite are completely inconsistent with a residual origin. Partial melting would have partitioned all sulfide in the source into the melt. In fact, no sulfide or silicate melt remained in the Dagzhuka peridotite. Therefore, PGE in Dagzhuka peridotite are not present in sulfides. The PGE\|enrichment and fractionation of the Dagz

关键词： platinum\|group elements(PGE) peridotites Dazhuka ophioli te Tibet

Experimental study of ore gabbro liquid immiscibility

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Science China Earth sciences 2005年第4期48卷 496-505页

作者： SANG Zunan1,2. XIA Bin1, ZHOU Yongsheng3 & JIN Zhenmin4 1. guangzhou institute of {2., chinese academy of sciences, guangzhou 51064., China 2. Wuhan University, Wuhan 430072. China 3. institute of Geology, China Seismological Bureau, Beijing 10002., China 4. Faculty of Earth sciences, China University of Geosciences, Wuhan 430074, China 1. guangzhou institute of {2. Chinese Academy of Sciences 510640 Guangzhou China 2. Wuhan University 430072 Wuhan China 3. institute of Geology China Seismological Bureau 100029 Beijing China 4. Faculty of Earth sciences China University of Geosciences 430074 Wuhan China

In this paper, the authors present the results of a preliminary experimental study on partial melting of fine-grained gabbro, Panzhihua, Sichuan Province, China. Experiments were conducted under (confining) pressure ranging from 450 to 500 MPa and temperature of 900— 12.0℃. The results show that the initial melt is distributed along grain boundaries and triple junctions. Liquid immiscibility phenomena are noted in the melt with two compositional different melt phases, i.e. matrix and sphere phases. The matrix phase is relatively rich in Si, Al and K, and is depleted in Mg, Fe, Ca, Na and Ti, whereas the sphere phase shows opposite trends. The calculation of the melt free energy indicates that the liquid immiscibility is governed by the rule of thermodynamics, as the liquid immiscibility would result in the decrease in free energy of the melt system. The field relationships suggest that the liquid immiscibility may have played an important role in the generation of ore magma of Panzhihua V-Ti magnetite ore deposit. This study thus provides experimental constraints on the mechanism of the formation of V-Ti magnetite deposite.

关键词： partial melting, experimental study, gabbro, liquid immiscibility, ore formation mechanism.

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 academy of sciences,{2., China 3. Department of Earth sciences, Zhongshan University, guangzhou 5102.5, China eeszhou@*** Department of Geography Tianjin Normal University Tianjin 300071 China guangzhou institute of {2. 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.

Digital image analysis of palaeoenvironmental records and applications

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chinese Science Bulletin 2002年第23期47卷 1957-1963,2025-2026页

作者： SUN Donghuai1,2. LIU Yu2.& TAN Ming31. South China Sea institute of Oceanology, chinese academy of sciences. {2. 510301, China 2. State Key Laboratory of Loess and Quaternary Geology, Earth Environmental institute, chinese academy of sciences, Xi’an 710075, China 3. institute of Geology and Geophysics, chinese academy of sciences, Beijing 10002., China South China Sea institute of Oceanology Chinese Academy of Sciences Guangzhou China State Key Laboratory of Loess and Quaternary Geology Earth Environmental Institute Chinese Academy of Sciences Xi’an China institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

Environmental change signals in geological or biological records are commonly reflected on their reflecting or transmitting images. These environmental signals can be extracted through digital image analysis. The analysis principle involves section line selection, color value reading and calculating environmental proxy index along the section lines, layer identification, auto-chronology and investigation of structure evolution of growth bands. On detailed illustrations of the image technique, this note provides image analyzing procedures of coral, tree-ring and stalagmite records. The environmental implications of the proxy index from image analysis are accordingly given through application demonstration of the image technique.

关键词： digital image environmental records.

On deposits controlled by tectonic lenses

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Science China Earth sciences 2004年第12期47卷 1095-1101页

作者： WANG Jincao 1 ,XIA Bin 1 & JI Shaocheng 2.1.guangzhou institute of {2.,chinese academy of sciences,guangzhou 51064.,China 2.Department of Civil,Geological and Mining Engineering,Montreal institute of Technology,P.O.Box6079,Station Centre-ville Montreal,Canada 1. chinese academy of sciences Guangzhou Institute of Geochemistry 510640 Guangzhou China 2. Department of Civil Geological and Mining Engineering Montreal Institute of Technology Station Centre-ville Montreal P. O. Box 6079 Canada

By study of the typical tectonic lenses controlling some ore deposits, the tectonic lens boundaries may be classified into fuzzy boundaries, sharp boundaries and complex boundaries, and the metallostructures in tectonic lenses may be classified into vein-type, stock- work-type and breccia-type. After studying their metallostructures, we suggest the conception on tectonic lenses as an ore-forming system, realizing that the compact-function ore-forming system is made up of the lenticular weak-strain domain(Q) and its outside linear strong-strain belt(P). The ore-forming system, which is composed of four subsystems that coupled with each other and exert their system functions to the full, includes the dual-dynamical system made up of tectonic and fluid dynamics, the metallotectonic system controlled by hydrofracturing, the ore-source system made up of multi-substances and the mineral transportation system contacted by tectonic network. Deformational partitioning, hydrofracturing and tectonic pumping operate the consid- erable function while the system function practises. Finally, the significance of metallotectonics on the tectonic lenses is discussed in the paper.

关键词： tectonic lenses, boundary type of tectonic lenses, type of metallostructures, tectonic lens as an ore-forming system.

Stage characteristics for the development of late Quaternary paleosols in the Yangtze Delta area

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chinese Science Bulletin 1999年第9期44卷 857-860页

作者： CHEN Qingqiang and LI CongxianLaboratory of Marine Geology , Tongji University , Shanghai 2.0092. China guangzhou institute of {2. , chinese academy of sciences , guangzhou 51064., China Laboratory of Marine Geology Tongji University Shanghai China guangzhou Institue of geochemistry Chinese Academy of Sciences Guangzhou China

The late Quaternary paleosols in the Yangtze Delta area developed in the period of 2. 000—12.000 aBP. Phytolith ratios (value A) of contents of fan, square and rectangle types indicaring the warm and humid climate to those of bar, hat and point types indicating cold and dry climates decrease upwards overall on profiles of the paleosols, suggesting that the climates turned from warm and humid to cold and dry. So, the paleosols developed mainly during the regression before the last glacial maximum. Changes of value A indicate no trend of warming, suggesting that the transgression was rapid after the last glacial maximum. The development of the paleosols exhibited obvious stages, which were controlled remarkably by transgression and regression: Ⅰ. Period of alternation of deposition and pedogenesis, which was from the occurrence of regresson before the last glacial maximum to the time when sea levels fell close to the lowest;Ⅱ. Exposure period with continual pedogenesis, which was terminated when the

关键词： paleosol phytolith development processes late Quaternary Yangtze Delta.