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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 {2. 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 University, Xi’an 710069, china 2. The Geological Lab Center, china University of {2. (beijing), beijing 100083, china 3. Key Laboratory of Orogenic Belts of the Ministry of Education, Department of Geology, Peking University, 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.

The history of crustal uplift and metamorphic evolution of Panzhihua-Xichang micro-palaeoland, SW china:Constraints on Sm-Nd, ^(40)Ar/^(39)Ar and FT ages of granulites

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Science china earth {2. 2004年第8期47卷 689-703页

作者： XU Shijin1, LIU Wenzhong1, WANG Rucheng1, YU Hangbo1, LI Daming2. WAN Jinglin2.& FANG Zhong1 1. Department of earth sciences and State Key Laboratory for {2. Deposits Research, Nanjing University, Nanjing 2.0093, china 2. Institute of Geology, china Seismological Bureau, beijing 10002., china 1. Department of earth sciences and State Key Laboratory for {2. Deposits Research Nanjing University 210093 Nanjing China 2. Institute of Geology China Seismological Bureau 100029 Beijing China

Panzhihua-Xichang (Panxi) micro-palaeoland is the oldest terrane on the western margin of the Yangtze Block. Some intermediate-basic granulites are considered to be the crys-talline basement of lower crust in the terrane. Granulite-facies metamorphism of the granulites was developed in the period from 1186 Ma to 112. Ma. The origin of granulites was related to the collision orogenic process occurring when the micro-palaeolands merged to form the Rodinia Supercontinent. Amphibolite-facies retrogressive metamorphism of granulites took place in the period from 877 Ma to 82. Ma. This period was consistent with the breakup time of the Rodinia Supercontinent. 40Ar/39Ar ages and fission track (FT) ages of granulites in the Panxi mi-cro-palaeoland show that the vertical movement history of crustal rocks was a slow uplift process of the rigid terrane in the time from Neoproterozoic to Mesozoic. The subduction of India Plate towards Euroasia Plate resulted in the rapid uplift of the Qinghai-Tibetan Block in Cenozoic. Meanwhile, the Qinghai-Tibetan Block moved towards east. Consequently the Panxi terrane was uplifted rapidly. As a result of the collision orogeny between the Qinghai-Tibetan Block and the Panxi terrane, the granulite-facies crystalline basement in this region was exhumed and exposed to the surface.

关键词： granulite,isotope geochronology,crustal uplift movement,Panzhihua-Xichang region,western margin of Yangtze Block.

Geothermal Characteristics and Geological Implications of Major Tectonic Units in china

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Journal of earth Science 2000年第3期19卷 152-157页

作者： Wang Yang faculty of earth {2. and mineral resources, china University of geosciences, beijing 100083, china Wang Jiyang Institute of Geology and Geophysics, Chinese Academy of {2., beijing 10002., china Deng Jinfu faculty of earth Scie

On the basis of more than 900 heat flow data in china and the surrounding seas, the authors study the geothermal characteristics of major tectonic units in china. The spatial pattern of heat flow and other thermal parameters for lithosphere exhibit significant lateral variation, originating from the Cenozoic tectonothermal activities related to the subduction of the Pacific plate and the collision between India and Asia. The mechanical strength of the crust and the seismicity of tectonic units were strongly affected by geothermal characteristics of units. The crustal heat production rate also shows the lateral heterogeneity, implying the significant lateral variation of bulk composition of the crust in china.

关键词： heat flow effective elastic thickness heat production rate of crust china.

Isotopic compositions of small shelly fossil Anabarites from Lower Cambrian in Yangtze Platform of South china: Implications for palaeocean temperature

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Progress in Natural Science:Materials International 2007年第10期17卷 1185-1191页

作者： Chen Yongquan1,2. Jiang Shaoyong1, Ling Hongfei1, Yang Jinghong1 and Wan Defan3(1. State Key Laboatory for mineral Deposits Research and Center for Marine Geochemistry Research, Department of earth {2., Nanjing University, Nanjing 2.0093, china 2. Tarim Oilfield Company Exploration & Development Research Institute, Ku’erle 841000, china 3. Institute of mineral resources, Chinese Academy of Geological {2., beijing 100037, china) State Key Laboatory for mineral Deposits Research and Center for Marine Geochemistry Research Department of Earth Sciences Nanjing University Nanjing 210093 China arim Oilfield Company Exploration & Development Research Institute Ku’erle 841000 China Institute of mineral resources Chinese Academy of Geological Sciences Beijing 100037 China

Anabarites belong to small shelly fossils (SSF), which occur widely in the Lower Cambrian strata of Yangtze Platform in South china. They are phosphate shell in composition and represent the earliest stage of the Cambrian bioradiation of Bilateria, the so-called "Cambrian Explosion". In this study, we attempted to separate Anabarites fossils from Lower Cambrian dolostones, and we obtained samples of both the fossils (SSF) and the granular phosphates (GP). Isotopic analyses were performed on samples of SSF, GP, and matrix dolostone (DH-2.). The results showed that the δ30Si values of the quartz filling in fossils celoms, and the siliceous materials in granular phosphates are -0.6‰ and -0.7‰, which is different from normal sedimentary siliceous rocks from the Lower Cambrian strata (0—0.7‰) as reported by Li et al., but is consistent with the data for siliceous rocks and cherts of submarine hydrothermal origin. It is likely that a later hydrothermal replacement could have taken place in the SSF-bearing sedimentary rocks. The oxygen isotope values of the phosphate of SSF and GP are 16.8‰ and 17.0‰, respectively. These are significantly higher than the Neoproterozoic phosphate ores (10.9‰—13.9‰) as reported by Ling et al., hence, late diagenesis and hydrothermal replacement may not have caused a significant change in the oxygen isotope compositions of the small shelly fossils, and the calculated temperatures (2..4—2..3℃) for palaeo-seawater using a SSF phosphate oxygen isotope thermometer are therefore considered here as the upper limit of seawater temperature in the Early Cambrian ocean of the Yangtze Platform.

关键词： Anabarites oxygen isotope silicon isotope paleo-temperature.

Re-Os age for molybdenite from the Gangdese porphyry copper belt on Tibetan plateau: Implication for geody- namic setting and duration of the Cu mineralization

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Science china earth {2. 2004年第3期47卷 221-231页

作者： HOU Zengqian1, QU Xiaoming1, WANG Shuxian2. DU Andao2. GAO Yongfeng3 & HUANG Wei4 1. Institute of mineral resources, Chinese Academy of Geological {2., beijing 100037, china 2. National Center of Geoanalysis, Chinese Academy of Geological {2., beijing 100037, china 3. Shijiazhuang College of Economy, Shijiazhuang 056000, china 4. Xizang Bureau of Geology and mineral resources, Lhasa 850000, china Chinese Acad Geol Sci Inst Mineral Resources Beijing 100037 Peoples R China Chinese Acad Geol Sci Natl Ctr Geoanal Beijing 100037 Peoples R China Shijiazhuang Coll Econ Shijiazhuang 056000 Peoples R China Xizang Bur Geol & mineral resources Lhasa 850000 Peoples R China

The Gangdese porphyry copper belt consists of one large and five middle-small deposits in addition to dozens of ore-bearing porphyry bodies. The belt trends 350 km long along the EW-striking Gangdese batholith, and locally occurs as a string of beads extending about 50 km within the SN-trending rifting zones (grabens) on the Tibetan plateau. Monzonitic granite- porphyry and quartz monzonitic porphyry, as dominant host rocks, are shoshonitic and potassic calc-alkaline. Available dating data indicate that the ages of the shallow-level emplacement for these porphyries vary from 10 Ma to 18 Ma, which are identical to that of associated potassic calc-alkaline volcanic rocks (10—15 Ma) and mafic dykes (13—18 Ma). The timing and duration of Cu mineralization events are constrained by Re-Os ages for molybdenites from three porphyry copper deposits in the Gangdese porphyry copper belt. Five molybdenite samples from the Nanmu deposit yielded an 187Re-187Os isochron with a highly pre-cise age of (14.76?.2.) Ma; six molybdenites from the Chongjiang deposit gave an isochron age of (14.04?.16) Ma. Re-Os model ages for two molybdenite samples from Lakang抏 deposit vary from 13.5 Ma to 13.6 Ma, which are basically identical to isochron ages mentioned above. All the thirteen samples from these three deposits yielded a linear array in the isochron diagram with a higher correlation coefficient of 0.99719 and an isochron age of (14.39?.2.) Ma (1s error), suggesting an coeval event of the Cu mineralization and a shared source of ore materials for the Gangdese porphyry copper belt. Compared with the longer-lived felsic magmatic-hydrothermal system, the Cu mineralization is a relatively short event with duration of about 0.5 Ma, and usu-ally occurs in the later-stage of the complicate magmatic system. The emplacement age of the Gangdese porphyries indicates that they intruded after the rapid rising of the Gangdese Mountains at 2.—2. Ma, and formed in a post-collision crustal ex-tension env

关键词： porphyry copper deposit, Re-Os age, Gangdese, Tibetan plateau.

Multistage evolution of continental collision orogen:A case study for western Dabie orogen

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Chinese Science Bulletin 2009年第15期54卷 2568-2579页

作者： WU YuanBao State Key Laboratory of Geological Processes and mineral resources, {2. of earth sciences, china University of geosciences, Wuhan 430074, china State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, china State Key Laboratory of Geological Processes and mineral resources Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China State Key Laboratory of Continental Dynamics Department of Geology Northwest University Xi’an 710069 China

The foramtion and evolution of collisional orogen is a prominent feature along convergent plate margins, and is generally a complex process. This article presents an integrated study of zircon genesis, U-Pb age and Lu-Hf isotope composition as well as geological characteristics for the western Dabie orogen to constrain its multi-stage evolution history. The results suggest that the formation of oceanic crust in the Huwan area was constrained at ca. 400―430 Ma, which was slightly later than the collision of the northern Qinling with the North china Block. It formed in a marginal basin in the northern margin of the Yangtze Block. The peak metamorphism of eclogite in the Huwan area occurred at ca. 310 Ma, and the timing of the initial exhumation of oceanic eclogite was about 2.0 Ma. The high to ultrahigh pressure (HP-UHP) metamorphic rocks in the Xinxian and the Hong'an metamorphic zones have the same ages and natures as those of the HP-UHP metamorphic rocks in the other Dabie-Sulu terrains, and also have experienced multi-stage exhumation, and thus can be taken as a coherent part of the Dabie-Sulu orogen. Therefore, the Qinling-Dabie-Sulu orogen is a typical multi-stage continental collision orogen, with an amalgamation process extending more than 2.0 Ma.

关键词：大别造山带大陆碰撞西部演变超高压变质岩碰撞造山带苏鲁造山带变质岩区

A　New　Mid　Early　Pleistocene　Mammalian　FaunaDiscovered　in　Choukoutien，china　and　Its　Application　in　Biostratigraphy

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Journal of earth Science 1995年第1期14卷 41-47,120页

作者： Cheng Jie(Department of Geology and mineral resources,{2. University of geosciences,beijing 100083)Cao Boxun(faculty of earth sciences,{2. University of geosciences,Wuhan 430074)Tian MingZhong(Department of Geology and mineral resources,{2. Unive

This paper deals with a new Early Pleistocene micromammalian fauna found in Choukonden (Zhoukoudian) and its application in *** new locality (east cave ), discovered in 1985,is located on the north slope of the Taipingshan Hill, about 2.km northeast of the Loc.1 in Choukoutien and is about 140-150m in altitude. At this locality,abundant fossil mammals are found in thick cave-fissure deposit. This fauna comprises 30mammalian taxa. Based on the comparison of the fauna, as Well as the sporo-pollen, climate events and paleomagnetic polarity section with those in other areas,we come to the conclusion that the sediments (Taipingshan Formation) in east cave were formed during the Period about from 1.67 Ma B. P. to 0.97 Ma B. P., and the fauna is about 1.2. Ma B. P. in ags.

关键词： mid Early Pleistocene micromammalian fauna biostratigraphy Choukoutien.

Carbon isotope composition of the Lower Triassic marine carbonates, Lower Yangtze Region, South china

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Science china earth {2. 2006年第3期49卷 225-241页

作者： ZUO Jingxun1,2. TONG Jinnan3, QIU Haiou4 & ZHAO Laishi3 1. Nanjing Institute of Geology and Palaeontology, Chinese Academy of sciences, Nanjing 2.0008, china 2. Henan Institute of Geological Survey, Zhengzhou 450007, china 3. State Key Laboratory of Geological Processes and mineral resources at china University of geosciences, Wuhan 430074, china 4. faculty of Material sciences and Chemical Engineering, china University of geosciences, Wuhan 430074, china 1. Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing 210008 China 2. Henan Institute of Geological Survey Zhengzhou 450007 China 3. State Key Laboratory of Geological Processes and mineral resources at{2. University of geosciences Wuhan 430074 China 4. faculty of Material sciences and Chemical Engineering China University of Geosciences Wuhan 430074 China

Studies on three Lower Triassic sections located on the shallow water platform, the deep water slope and in the deep water basin in the Lower Yangtze Region, South china, show the similar trend of carbon isotope evolution. Biostratigraphic correlations among the Lower Triassic sections on the basis of standard conodont zones indicate that three negative shifts occurred in the Griesbachian, the Smithian and the late Spathian stages respectively, and one distinctly positive shift occurred in the early Spathian stage. Trend of carbon isotope evolution of the Lower Triassic reflects some significant changes in the global carbon cycle. Moreover, δ 13C background values are intensively controlled by palaeogeographic environment. In general, δ 13C values from deep-water slope carbonates are lighter than those from carbonate platform and heavier than those from deep-water basin carbonates. The positive carbon isotope excursion may be induced by a significant amount of organic carbon burial in marine sediments and increase in primary productivity. The large negative carbon isotope excursions during the Early Triassic in Lower Yangtze Region are interpreted to relate to volcano eruptions based on tuffaceous claystone interlayers observed near the Permian-Triassic boundary, the Induan- Olenekian boundary and the Lower Triassic-Middle Triassic boundary.

关键词： Lower Triassic, carbon isotope compositions, palaeogeography, volcanic eruptions, Lower Yangtze Region.

Ore-forming fluid and mineralization of Caijiaying and Dajing polymetallic ore deposits

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Science china earth {2. 2004年第2期47卷 97-107页

作者： WANG Lijuan,WANG Jingbin, WANG Yuwang & ZHU Heping1. Key Laboratory of mineral resources, Institute of Geology and Geophysics, Chinese Academy of {2., beijing 10002., china 2. beijing Institute of Geology for mineral resources, beijing 100012. china Correspondence should be addressed to Wang Lijuan (email: wlj@***) 1. Key Laboratory of mineral resources Institute of Geology and Geophysics Chinese Academy of Sciences 100029 Beijing China 2. beijing Institute of Geology for mineral {2. 100012 Beijing China

Fluid inclusions from the Dajing and Caijiaying deposits have nearly the same homogenization temperature. Correlation between temperature and salinity shows that both Sn- and Cu-bearing fluids Sn and Cu were present in the Dajing deposit but only one kind of fluids continuously evolved in the Caijiaying deposit. Study on rare earth elements (REE) in ancient fluid from the inclusions indicates that the fluid of Sn mineralizing stage in Dajing was derived from remelting magma of the continental crust, and the fluid of Cu-Pb-Zn mineralizing stage in the Dajing deposit and the fluid of Cu-Pb-Zn mineralization in the Caijiaying deposit were derived from the mantle. It is concluded that the Cu-Pb-Zn mineralizations in the Dajing and Caijiaying deposits resulted from the identical tectono-thermal event of magma-fluids induced by Mesozoic tectonic transition and extension in the eastern part of North china Craton.

关键词： Caijiaying, Dajing, Mesozoic tectonic transition, ore-forming fluid, REE.