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Petrogenesis of songshugou dunite body in the Qinling orogenic belt, Central china: Constraints from geochemistry and melt inclusions

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science china Earth sciences 2005年第8期48卷 1146-1157页

作者： sU Li1,2. sONG shuguang3 & ZHOU Dingwu1 1. Key laboratory of Continental Dynamics of the Ministry of Education, Department of geology, Northwestern {2., Xi’an 710069, china 2. the geological lab center, china {2. of geosciences (beijing), beijing 100083. china 3. Key laboratory of Orogenic Belts of the Ministry of Education, Department of geology, Peking {2., beijing 100871, china 1. Key laboratory of Continental Dynamics of the Ministry of Education Department of Geology Northwestern University 710069 Xi’an China 2. the geological lab center China University of Geosciences 100083 (Beijing)Beijing China 3. Key laboratory of Orogenic Belts of the Ministry of Education Department of Geology Peking University 100871 Beijing China

The songshugou dunite body, which occupies an area of about 2. km2. is the largest ultramafic massif in the eastern Qinling orogenic belt, Central china. The major compo-nent of this body is dunitic rocks including mylonitic dunite and coarse-grained dunite; they oc-cupy about 95 vol% of the total body. Petrography, mineral composition, major and trace ele-ments and primitive melt inclusions have been investigated in this paper; all revealed that this dunite body is the product of melt-rock interaction by porous percolation flow. In comparison with dunite sills or veins in harzburgite from the basal part of Oman ophiolite, this dunite body is characterized by lower contents of Al2.3, CaO and HREE but higher content of highly incom-patible elements and Zr and Hf. The LREE enriched patterns and primitive mantle normalized spidergrams of trace elements are also different from the Oman dunite. Combining with melt in-clusions observed in olivines, we conclude that this dunite body is the product of large- scale porous percolation flow of high-MgO melts within depleted mantle peridotites. The high-MgO magma, in essence, was most probably produced at the hot head of an upwelling mantle plume. The occurrence of the songshugou dunite body is closely associated with the activity of mantle super-plume in Neo-Proterozoic era in the Yangtze Craton.

关键词： songshugou dunite body, geochemistry, melt inclusion, mantle plume, Qinling orogenic belt.

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sHRIMP U-Pb dating and Hf isotopic analyses of Middle Ordovician meta-cumulate gabbro in central Qiangtang, northern Tibetan Plateau

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science china Earth sciences 2010年第5期53卷 657-664页

作者： ZHAI QingGuo1 WANG Jun1, LI Cai2.& sU Li3 1 Institute of geology, Chinese Academy of geological sciences, {2. 100037, china 2.College of Earth sciences, Jilin university, Changchun 130061, china 3 The geological laboratory center and state Key laboratory of geological Processes and Mineral Resources, china university of geo- sciences, beijing 100083. china 1. Institute of geology Chinese Academy of Geological Sciences Beijing 100037 China2. College of Earth Sciences Jilin University Changchun 130061 China3. The Geological Laboratory Center and State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China

Metabasites consisting of metamorphic ultra-mafic rocks, cumulate gabbro, gabbro (diabase), basalt, and plagiogranite are exposed at the Taoxinghu area in central Qiangtang, northern Tibetan Plateau. Zircon sHRIMP U-Pb dating for the cumulate gabbro yields a weighted mean age of 467±4 Ma, which is the oldest and most reliable magmatic age in this area. Zircon 176Hf/177Hf ratios range from 0.2.2.15 to 0.2.2.57, with εHf(t) values of 5.02.0.2., indicating that the cumulate gabbro was mainly derived from the depleted mantle. In addition, geochemical data of metabasites suggest that they have similar characteristics to those in the mid-ocean ridge basalts (MORB). The Taoxinghu metabasites may represent the fragment of Early Paleozoic ophiolite in the "Central Uplift" of the Qiangtang, northern Tibetan Plateau.

关键词： Qiangtang cumulate gabbro sHRIMP dating Hf isotope

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On some tests-based projection pursuit for elliptical symmetry of a high-dimensional distribution

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Chinese science Bulletin 1998年第6期43卷 450-458页

作者： JING Ping 1 and ZHU Lixing 2.1. Mathematics lab, china {2. of Mining & Technology, beijing 100083. china 2. Probability lab, Institute of Applied Mathematics, Chinese Academy of sciences, beijing 100080, china Mathematics lab China University of Mining & Technology Beijing China Probability lab Institute of Applied Mathematics Chinese Academy of Sciences Beijing China

some test statistics of Kolmogorov type and Cramér-von Mises type based on projection pursuit technique are proposed for the testing problem of sphericity of a high-dimensional distribution. The limiting distributions of the test statistics are derived under the null hypothesis and under any fixed alternative. The asymptotic properties of bootstrap approximation are investigated. Furthermore, for computational reasons, an approximation for the statistics, based on the number theoretic method, is suggested.

关键词： bootstrap approximation projection pursuit type statistic elliptical symmetry.

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Indian Ocean-MORB-type isotopic signature of Yushigou ophiolite in North Qilian Mountains and its implications

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science china Earth sciences 2006年第6期49卷 561-572页

作者： HOU Qingye1,2. ZHAO Zhidan1,2. ZHANG Hongfei3, ZHANG Benren3 & CHEN Yuelong2.1. state Key laboratory of geological Processes and Mineral Resources, {2. university of geosciences, beijing 100083. china 2. school of Earth science and Mineral Resources, {2. university of geosciences, beijing 100083. china 3. Faculty of Earth sciences, {2. university of geosciences, Wuhan 430074, {2. 1. state Key laboratory of geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China 2. school of Earth science and Mineral Resources China University of Geosciences Beijing 100083 China 3. Faculty of Earth sciences China University of Geosciences Wuhan 430074 China

In order to explore the disputed issue concerning the tectonic affinity ofthe ancient ocean mantle of North Qilian Mountains (NQM), geochemical and sr, Nd, Pb isotopiccompositions of pillow basalts of the Yushigou Ophiolite (YsGO) suite from NQM have been analyzedsystematically. The pillow basalts exhibit tholeiitic characteristics, with flatchondrite-normalized REE patterns ((La/Yb)_N = 0.98—1.2.). They display no Nb, Ta, Zr, Hf negativeanomalies, and show MORB features in 2.b-Zr/4-Y and Ti/100-Zr-YX3 tectonic discrimination *** results indicate that the Yushigou ophiolite is most likely to be formed in a mid-ocean ridgeor mature back-arc basin. Their isotopic data show a relatively broad and enriched ^(87)sr/^(86)sr(0.70509 — 0.70700), restricted ^(143)Nd/^(144)Nd (0.512.55-0.512.78). Pb isotopes are in the rangeof ^(2.6)Pb/^(2.4)Pb (18.054-2..562., ^(2.7)Pb/^(2.4)Pb (15.537-15.743) and ^(2.8)Pb/^(2.4)Pb(38.068-38.530). These isotopic data imply that the basalts originated from the depleted mantle(DMM), with the involvement of enriched mantle components (mainly EMII). geochemical comparisonsbetween the basalts in YsGO and the MORB-type basalts of ophiolite suites occurring in the knownancient Tethyan tectonic domain indicate that the ancient oceanic mantle represented by YsGO suiteforming in early Paleozoic in the North Qilian Moutains is very similar to the Tethyan mantle inboth trace elements and isotopic compositions. The North Qilian Mountains should be a part of theTethyan tectonic domain in early Paleozoic. This further implies that the Tethyan tectonic domaincan be deduced to early Paleozoic in the study area, which will be helpful to discussing thetectonic affinity and evolution of the North Qilian Mountains.

关键词： geochemistry, Indian Ocean-MORB-type isotopic signatures, Tethyan tectonic domain, Yushigou ophiolite, North Qilian Mountains.

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Mechanism for calcite dissolution and its contribution to development of reservoir porosity and permeability in the Kela 2.gas field,Tarim Basin,china

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science china Earth sciences 2008年第4期51卷 567-578页

作者： YU Bingsong1,3, DONG HailLiang2.3 & RUAN Zhuang1,3 1 state Key laboratory of geological Processes and Mineral Resources, {2. university of geosciences, beijing 100083. china 2.Department of geology, Miami university,Oxford, OH 45056, UsA 3 geomicrobiology laboratory, {2. university of geosciences, beijing, 100083. {2. state Key laboratory of geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China Department of geology Miami University Oxford OH 45056 USA geomicrobiology laboratory China University of Geoscien

This study is undertaken to understand how calcite precipitation and dissolution contributes to depth-related changes in porosity and permeability of gas-bearing sandstone reservoirs in the Kela 2.gas field of the Tarim Basin, Northwestern china. sandstone samples and pore water samples are col-lected from well KL2.1 in the Tarim Basin. Vertical profiles of porosity, permeability, pore water chem-istry, and the relative volume abundance of calcite/dolomite are constructed from 3600 to 4000 m below the ground surface within major oil and gas reservoir rocks. Porosity and permeability values are in-versely correlated with the calcite abundance, indicating that calcite dissolution and precipitation may be controlling porosity and permeability of the reservoir rocks. Pore water chemistry exhibits a sys-tematic variation from the Na2.O4 type at the shallow depth (3600-3630 m), to the NaHCO3 type at the intermediate depth (3630―3695 m),and to the CaCl2.type at the greater depth (372.―3938 m). The geochemical factors that control the calcite solubility include pH, temperature, pressure, Ca2. concen-tration, the total inorganic carbon concentration (ΣCO2., and the type of pore water. Thermodynamic phase equilibrium and mass conservation laws are applied to calculate the calcite saturation state as a function of a few key parameters. The model calculation illustrates that the calcite solubility is strongly dependent on the chemical composition of pore water, mainly the concentration difference between the total dissolved inorganic carbon and dissolved calcium concentration (i.e., [ΣCO2. -[Ca2.]). In the Na2.O4 water at the shallow depth, this index is close to 0, pore water is near the calcite solubility. Calcite does not dissolve or precipitate in significant quantities. In the NaHCO3 water at the intermedi-ate depth, this index is greater than 0, and pore water is supersaturated with respect to calcite. Massive calcite precipitation was observed at this depth interval and

关键词： calcite dissolution porosity thermodynamic Tarim Basin

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The equilibrium between diagenetic calcites and dolomites and its impact on reservoir quality in the sandstone reservoir of Kela 2.gas field

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Progress in Natural science:Materials International 2007年第9期17卷 1051-1058页

作者： Gao Zhiqian1,Yu Bingsong2.3 and Lai Xingyun2.3(1.school of Energy Resources,china university of {2.sciences,beijing 100083.china 2.state Key laboratory of geological Processes and Mineral Resources,china university of {2.sciences,beijing 100083.china 3.Ministry of Education Key laboratory of Lithosphere structure,Deep Processes and Exploration Technique,china university of {2.sciences,beijing 100083.china) school of Energy Resources China University of Geosciences Beijing 100083 China state Key laboratory of geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China Ministry of Education Key laboratory of Lithosphere structure Deep Processes and Exploration Technique China University of Geosciences Beijing 100083 China

Based on the equilibrium theory of chemical reactions between water and rocks,this paper establishes a thermodynamic phase relationship diagram among calcites,dolomites and water solution under the condition of diagenesis based on the thermodynamic database of related minerals and fluids and dolomite's degree of order *** has been discovered that the equilibrium between calcites and dolomites in the diagenetic environment is strongly impacted by temperature and the Ca/Mg ratios in groundwater,and that the dolomite's degree of order in the diagenetic environment is a function of crystallization temperature and time,not controlled by water ***,the authors make a further analysis of the close relationship of chemical reaction between carbonate cements and pore water in the sandstone reservoirs of Kala 2.gas field in Kuche *** can be seen that there are different impacts on sandstone reservoir quality among the equilibrium system of calcites,dolomites and pore water at different depths of reservoirs.

关键词： diagenesis equilibrium between calcites and dolomites secondary pores Kela 2.gas field

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Petrogenesis and dating of the Kangding complex,sichuan Province

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science china Earth sciences 2005年第5期48卷 622-634页

作者： CHEN Yuelong 1 , LUO Zhaohua 1 , ZHAO Junxiang, LI Zhihong, ZHANG Hongfei & sONG Biao 3 1. Faculty of Earth sciences and Natural Resources, china university of {2.sciences, beijing 100083. china 2. Faculty of Earth sciences, china university of {2.sciences, Wuhan 430074, china 3. beijing sHRIMP center, Institute of {2.logy, Chinese Academy of geological sciences, beijing 100037, china 1. Faculty of Earth sciences and Natural Resources China University of Geosciences 100083 Beijing China 2. Faculty of Earth sciences China University of Geosciences 430074 Wuhan China 3. beijing sHRIMP center Institute of Geology Chinese Academy of Geological Sciences 100037 Beijing China

An analysis of major and trace element geochemistry and sHRIMP U-Pb zircon dating of mafic, intermediate, and felsic rocks from the Mianning metamorphic complex of si- chuan Province was conducted. One of our conclusions is that a majority of the zircons crystal- lized between 72. and 773 Ma in a magmatic regime. The complexes contain early to late Pa- leo-proterozoic relict zircons from ancient continental crust. The oldest age, 2.68 Ma, may rep- resent the basement of the Yangtze block. Overgrowth zircon rims and palingenetic zircons have been observed and dated, and are believed to have formed after crystallization, during Paleozoic and Mesozoic metamorphic-anatexis. We also conclude that depletion of Nb, Ta, HREE, in a spider-diagram normalized to primitive mantle and calc-alkaline association, implies that they formed in island-arc or under-plating settings.

关键词： Kangding complex, zircons, sHRIMP, tectonic setting.

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Lithosphere types in North china:Evidence from geology and geophysics

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science china Earth sciences 2005年第11期48卷 1809-1827页

作者： QIU Ruizhao1,2. DENG Jinfu3, ZHOU su3, LI Jinfa4, XIAO Qinghui1,5, WU Zongxu6 & LIU Cui3 1. Institute of geology, Chinese Academy of geological sciences, {2. 100037, china 2. Development and Research center, china geological survey, {2. 100037, china 3. china university of geosciences,{12. 4. china university of geosciences, Wuhan 430074, china 5. Information center of Ministry of Land and Resources, {2. 100812. china 6. Institute of geology, state seismological Bureau, {2. 10002., china 1. Institute of geology Chinese Academy of Geological Sciences 100037 Beijing China 2. Development and Research center China Geological Survey 100037 Beijing China 3. china university of {2.sciences 100083 Beijing China 4. china university of {2.sciences 430074 Wuhan China 5. Information center of Ministry of Land and Resources 100812 Beijing China 6. Institute of geology State Seismological Bureau 100029 Beijing China

On the basis of the characteristics of geology and geophysics in North {2., three types of lithosphere, namely, the cratonic, the orogenic and the rift lithospheres can be classified. In terms of petrological method (based on the information from Precambrian rock assemblages, igneous activities, deep-seated enclaves, etc.) and the relationship between seismic velocity and rock compositions, the crust-mantle petrological and chemical structure models can be set up. Researching results indicate that the geology and geophysics of North {2. platform bears the similar characteristics in comparison with those of the global typical cratons. The Eerduosi(Ordos) block located in the west of the North {2. Platform is a remnant of cratonic lithosphere after the North {2. platform had undergone “activation” in Mesozoic and “reconstruction” in Cenozoic times. The continental crust consists mainly of TTG rock assemblage while the subcontinental lithosphere mantle mainly consists of strongly depleted harzburgite. The craton was finally formed in late Archaean and early Proterozoic, and has been kept in stability up to present; its crustal-mantle petrological structures of lithosphere can be set up as a reference for the study of North {2. craton and even sino-Korean craton. In the Mesozoic period, the middle and east areas of North {2. platform were activated in the Yanshanian orogenic process, the continental crust was reformed by material and heat-transfer of convective mantle and the original crustal TTG component was reconstructed to be granitic crust, and the subcontinental lithosphere man- tle was replaced by the Yanshanian harzburgite-lherzolite. The Yanshan-Taihang Mountains were the remnants of orogenic lithosphere after the rifting in eastern North {2. in Cenozoic. The present thickness of continental crust and lithosphere in the Yanshan-Taihang Mountains is not equal to their thickness during the Yanshanian orogenic movement because they had undergone the

关键词： lithospheric types,evidence of geology and geophysics,crust-mantle petrological structure,deep process

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Transport network and flow mechanism of shallow ore-bearing magma in Tongling ore cluster area

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science china Earth sciences 2006年第4期49卷 397-407页

作者： DENG Jun1,2. WANG Qingfei1,2., HUANG Dinghua3 , WAN Li4, YANG Liqiang1,2.& GAO Bangfei1,2.1. state Key laboratory of geological Processes and Mineral Resources, {2. university of geosciences, beijing 100083. china 2. Key laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education, {2. university of geo- sciences, beijing 100083. china 3. Faculty of Earth sciences, {2. university of geosciences, Wuhan 430074, {2. 4. school of Mathematics and Information science, Guangzhou university, Guangzhou 510405, {2. 1. state Key laboratory of geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China 2. Key laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education China University of Geosciences Beijing 100083 China 3. Faculty of Earth sciences China University of Geosciences Wuhan 430074 China 4. school of Mathematics and Information science Guangzhou University Guangzhou 510405 China

Abundant studies revealed that shallow intrusions of the Yanshanian epoch resulted in the mass mineralization of the Tongling region. Various evidences showed there existed a concealed magma chamber at ?10 km depth in the middle part of this region during Yanshanian epoch, from which the ore-forming magma was generated and then transported to the superficial layer. Yet the transport network and flow mechanism of the shallow ore-bearing magma, the key problem associ- ated with ore-forming process, was relatively little focused on. Integrate analysis of structural me- chanics, statistical fractal and geological facts suggested that NE trending high-angle fold-related thrust faults and the tessellated basement ones served as the main pathways for the shallow magma’s transporting, moreover, the saddle void spaces among adjacent strata in the folds upon this fault system provided the place for magma’s emplacement. so the folds in the upper part and faults in the lower part of the upper crust constituted the fluid’s transport and emplacement network. During the deformation of geologic body with multi-layer structure, the layers in the upper part tended to fold when received the jacking stress from the lower part, while the lower one inclined to fault undergoing loads of the upper part. And the producing probability of this structure assemblage was highly in- creased in the condition, such as in the Tongling area, that the mechanic rigidity of the lower layers was stronger than that of the upper ones. For the pre-existence of fluid-conducting network, the top magma with high volatile in the magma chamber transported rapidly to the superficial layer in dyking pattern, located in the void spaces of folds, filled and reconstructed them. The sudden drop of pres- sure caused the fluid unmixing from the magma and mass ore-forming elements concentration. Pulse activity of the dyking may be the principal reason why magmatic bodies in the Tongling area were spatially-temporally con

关键词： Tongling, structural network, magma intrusion, fractal, dyke.

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science china Earth sciences 2004年第10期47卷 896-911页

作者： ZHANG Changhou1,2. WU Ganguo1,2. WANG Genhou2. ZHANG Weijie2.& sONG Honglin2.1. Key laboratory of Lithospheric Tectonics and Lithoprobing Technology, china {2. of {3.sciences, Ministry of Education of china, beijing 100083. china 2. school of Earth sciences and Mineral Resources, china {2. of {3.sciences, beijing 100083. china 1. Key laboratory of Lithospheric Tectonics and Lithoprobing Technology China University of Geosciences Ministry of Education of China 100083 Beijing China 2. school of Earth sciences and Mineral Resources China University of Geosciences 100083 Beijing China

The northwest trending tectonic belt in the middle part of the Mesozoic intraplate Yanshan Orogenic Belt, northeast Hebei Province, is composed of thrusts, extensional faults, strike-slip faults and syntectonic sedimentations as well. The northeastward basement-involved major thrusting deformation occurred between 174Ma and 168MaBP and was followed by an intrusion of the granitic plutonic rocks. As a part of the post-thrusting extensional deformations a northwest extending volcano-sedimentation system of Late Jurassic and Early Cretaceous formed in the southwest side of the belt. These volcano-sedimentary sequences are divided into Tuchengzi Formation, Zhangjiakou Formation, Yixian Formation and Jiufotang Formation re- spectively. They are characterized by southeastward migration as a result of the increasing down-dip slip displacement along the major extensional fault toward the southeast of the belt. The provenance area of the Jiufotang Formation north to it experienced southwestward thrusting during and after its later sedimentation. The thrusting in this stage resulted in the formation of an asymmetric footwall syncline with vergence to sW in the Jiufotang Formation in the NE side of the basin. Finally a dextral strike-slip deformation occurred along the NW tectonic belt. The striking tectono-geomorphological features and present seismic activities along this belt indicate that it has been being active since Cenozoic era and is still in the active state at present. This northwest extending tectonic belt was following the same direction and location as the existing fault systems within the basement as revealed by former geological and geophysical studies. so it is reasonable to infer the Mesozoic deformation along this belt to be a result of reactivation of the basement structures in a favorable tectonic stress field. The reactivation of basement struc- tures might be taken as one of the mechanisms of intraplate deformation and orogeny.

关键词： Yanshan Orogenic Belt, northwest extending tectonic complex, thrust system, geochronology.

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