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shrimp zircon U-Pb geochronology of early Mesozoic felsic igneous rocks from the southern Lancangjiang and its tectonic implications

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Science china Earth sciences 2006年第10期49卷 1032-1042页

作者： PENG Touping1,2, WANG Yuejun1, FAN Weiming1, LIU Dunyi3. SHI Yuruo3.& MIAO Laicheng4 1. Key laboratory of isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, chinese {3. of sciences, Guangzhou 510640, china 2. Graduate University of chinese {3. of sciences, Beijing 10003., china 3. shrimp isotope laboratory, chinese academy of geological sciences, Beijing 10003., china 4. Institute of Geology and Geophysics, chinese {3. of sciences, Beijing 100029, china Key laboratory of isotope Geochronology and Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Graduate University of chinese academy of sciences Beijing China shrimp isotope laboratory Chinese Academy of Geological Sciences Beijing China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

The shrimp zircon U-Pb geochronology of three typical samples, including two monzo nitic granites from the Lincang batholith and a rhyolite from the Manghuai Formation are presented in the southern Lancangjiang, western Yunnan Province. The analyses of zircons for the biotite monzonitic granites from the northern (02DX-13.) and southern (20JH-10) Lincang batholith show the single and tight clusters on the concordia, and yield the weighted mean 206Pb/23.U ages of 229.4 ± 3.0 Ma and 23..4 ± 3.6 Ma, respectively, representing the crystallized ages of these granites. The zircons for the rhyolitic sample (02DX-95) from the Manghuai Formation give a weighted mean 206Pb/23.U age of 23..0 ± 5.0 Ma. These data suggest that the igneous rocks from the Lincang granitic batholith and Manghuai Formation have a similar crystallized age. In combination with other data, it is inferred that both were generated at a narrow age span (~23. Ma) and were originated from the postcollisional tectonic regime. An early Proterozoic 206Pb/23.U apparent age of 1977±44 Ma is additionally obtained from one zircon from the biotite monzonitic granite (southern Lincang batholith), indicative of devel- opment of the early Proterozoic Yangtze basement in the region. These precisely geochronological data provide important constraints on better understanding the Paleozoic tectonic evolution of the Tethys, western Yunnan Province.

关键词： shrimp zircon U-Pb dating, Middle Triassic, Lincang granitic batholith, Manghuai Formation rhyolite, southern Lancangjiang.

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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 Geosciences, Beijing 100083. china 2. Faculty of Earth sciences, china University of Geosciences, Wuhan 43.074, china 3. Beijing shrimp Center, Institute of Geology, chinese academy of geological sciences, Beijing 10003., china Faculty of Earth sciences and Natural Resources China University of Geosciences Beijing China Faculty of Earth sciences China University of Geosciences Wuhan China Beijing shrimp Center Institute of Geology Chinese Academy of Geological Sciences 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 721 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, 2468 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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U-Pb dating of zircon from the bed parallel anatectic granitic intrusion in the Baoban group in Hainan Island and the tectonic implication

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Science china Earth sciences 2005年第12期48卷 2092-2103页

作者： DING Shijiang1, HU Jianmin2, SONG Biao3.4, CHEN Mulun1, XIE Shengzhou1 & FAN Yuan1 1. geological Surveying Institute of Hainan, Haikou 570206, china 2. Institute of Geomechanics, chinese academy of geological sciences, Beijing 100081, china 3. Beijing Center of shrimp, Beijing 10003., china 4. Institute of Geology, chinese academy of geological sciences, Beijing 10003., china geological Surveying Institute of Hainan Haikou China Institute of Geomechanics Chinese Academy of Geological Sciences Beijing China Beijing Center of shrimp Beijing China Institute of Geology Chinese Academy of Geological Sciences Beijing China

The petrological and geochemical features of the bed parallel granitic intrusion in the Pre-Cambrian Baoban group in Hainan Island attest to the anatexis origin of the granites. U-Pb dating analyses of zircons from the anatectic granite and the biotite two-feldspar gneiss in the Baoban group, using shrimp II in the Beijing Ion-probe Center, acquire 206Pb/23.U ages of 3.8±3.5 Ma (of granite, 95% confidence level, MSDW=1.23. and 3.2.9±6.1 Ma (of gneiss, 95% confidence level, MSDW = 2.04) respectively. The two late Devonian ages indicate consistently a tectonic- thermal event experienced in Hainan Island, and are the first discovered record of the Devonian geological process in the district. This event possibly resulted from the deep ther-mal-dynamic process when the Gondwana continent began to break up in the Devonian period.

关键词： Hainan Island, Devonian period, anatectic granite, zircon shrimp U-Pb dating.

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

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Science china Earth sciences 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 210008,{3. 2. Henan Institute of geological Survey, Zhengzhou 450007,{3. 3. State Key laboratory of geological Processes and Mineral Resources at{3. University of Geosciences, Wuhan 43.074,{3. 4. Faculty of Material sciences and Chemical Engineering,{3. University of Geosciences, Wuhan 43.074,{3. Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing China Henan Institute of geological Survey Zhengzhou China State Key laboratory of geological Processes and Mineral Resources at china University of Geo{3. Wuhan China Faculty of Material sciences and Chemical Engineering China University of Geosciences Wuhan 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 13. background values are intensively controlled by palaeogeographic environment. In general, δ 13. 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.

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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, Beijing 10003., china 2 College of Earth {3., Jilin University, Changchun 13.061, china 3.The geological laboratory Center and State Key laboratory of geological Processes and Mineral Resources, china University of Geo- {3., Beijing 100083. china Institute of Geology Chinese Academy of Geological Sciences Beijing China College of Earth sciences Jilin University Changchun China The geological laboratory Center and State Key laboratory of geological Processes and Mineral Resources China University of Geosciences Beijing 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 0.282615 to 0.282657, with εHf(t) values of 5.02±0.28, 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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Re-Os(ICP-MS)dating of the massive sulfide ores from the Jinchuan Ni-Cu-PGE deposit

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Science china Earth sciences 2005年第10期48卷 1672-1677页

作者： YANG Gang1,2, DU Andao1, LU Jiren3. QU Wenjun1 & CHEN Jiangfeng2 1. National Research Center of Geoanalysis, Beijing 10003., china 2. laboratory for Earth Material Cycling, School of Earth and Space {3., University of Science and Technology of china, Hefei 23.026, china 3. Institute of Mineral Resource, chinese academy of geological sciences, Beijing 10003., china National Research Center of Geoanalysis University of Science and Technology of china chinese academy of geological {3.

Massive sulfide ore from the Jinchuan Ni-Cu-PGE deposit was dated by Re-Os technique using Carius Tube digestion, Os distillation, Re extraction by acetone and ICP-MS measurement. An isochron giving an age of 83. ± 3. Ma, initial 187Os/188Os ratio of 0.279 ± 0.018 (MSWD = 1.7) and γOs = 13. ± 15 is obtained. The Re-Os age obtained agrees, within analytical uncertainties, with previous shrimp zircon U-Pb age of 827 ± 8 Ma (n=5, MSWD = 4.3.. The result suggests that the deposit was formed at Neoproterozoic and that the formation of the Jinchuan Ni-Cu-PGE sulfide deposit may be closely related to the plume activity, which were attributed to the breakup of the Rodinia supercontinent. The high γOs of the massive ores sug-gests that crustal material was involved in the formation of the Jinchuan deposit, however, the quantity of the added crustal material is less than 10%.

关键词： Jinchuan Ni-Cu-PGE deposit, Re-Os dating, ICP-MS.

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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 sciences, Nanjing University, Nanjing 210093. china 2. Tarim Oilfield Company Exploration & Development Research Institute, Ku’erle 841000, china 3. Institute of Mineral Resources,{3., Beijing 10003., china) State Key laboratory for Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing 210093 China Exploration and Development Research Institute Tarim Oilfield Company 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-23.. The results showed that the δ3.Si 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 (25.4—26.3.) 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.

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Geochemistry of high-Mg andesites from the early Cretaceous Yixian Formation, western Liaoning: Implications for lower crustal delamination and Sr/Y variations

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Science china Earth sciences 2006年第9期49卷 904-914页

作者： WANG Xiaorui1, GAO Shan1,2, LIU Xiaoming1, YUAN Honglin1, HU Zhaochu1, ZHANG Hong1,3.& WANG Xuance4 1. State Key laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi`an 710069, china 2. State Key laboratory of {3. Processes and Mineral Resources, china University of Geosciences, Wuhan 43.074, china 3. Shenyang Institute of Geology and Mineral Resources, Shenyang 11003., china 4. Guangzhou Institute of Geochemistry, chinese academy of sciences, Guangzhou 510640, china State Key laboratory of Continental Dynamics Department of Geology Northwest University Xi’an China State Key laboratory of geological Processes and Mineral Resources China University of Geosciences Wuhan China Shenyang Institute of Geology and Mineral Resources Shenyang China Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China

85 volcanic rocks of the Yixian Formation from the Sihetun type section werecollected and analyzed for geochemical and isotopic compositions. Major element compositionsindicate that the Sihetun volcanic rocks are high magnesium andesites with some basalts occurring atthe bottom of section. The Sihetun high magnesium andesites (SiO_2 = 52.82-59.3. wt%, Al_2O_3.14.15-16.3.wt%) show many characteristics of adakites such as depletion in heavy rare-earth elements(HREE; Yb = 1.03.1.88 μg/g) and Y(12-20 μg/g) and high Sr (620-13.3.μg/g) and Sr/Y(3.-88), withhigh La_N/Yb_N ratio (10-25). They share similar major and trace element characteristics to volcanicrocks from the Xinglonggou Formation except their lower Nd isotope ratios (^(143.Nd/^(144)Nd(13.Ma) = 0.5118-0.5119, ε_(Nd) (13.Ma) = -11.6-13.8, ^(87)Sr/^(86)Sr (13. Ma) = *** were interpreted in a way that eclogite that formed at the base of thickened Archean lowercrust of the North china craton foundered into the convecting mantle and subsequently melted andinteracted with peridotite. However, compared to the Xinglonggou volcanic rocks, the source of theSihetun magma contained more ancient continental crustal material in order to explain its evolved Ndisotopes. The age of the Sihetun Formation was 120 to 13. Ma, and this indicates that delaminationlasted to the early Cretaceous period. The Sr contents and Sr/Y ratios of the Sihetun high-Mgandesites show significant negative correlations with SiO_2 for samples with SiO_2 > 56%. Thesesuggest that the Sr and Sr/Y values were reduced due to fractional crystallization of ***, the effect of crystallization on volcanic Sr and Sr/Y ratio has to be taken intoaccount.

关键词： High-Mg andesite, Adakite, Yixian Formation, North china Craton, delamination.

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Carbon and Oxygen Stable isotope Values and Microfossils at 41.4-4.5ka BP in Tai Co,Tibet,china,and Their Paleoclimatic Significance

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Acta Geologica Sinica(English Edition) 2011年第5期85卷 1036-1050+1052-1056+1051页

作者： ZHENG Mianping~(1,2,*),LIU Junying~(1,3.,MA Zhibang~(1,4),WANG Hailei~(1,2) and MA Nina~(1,2) 1 MLR Key laboratory of Saline Lake Resources and Environment,Institute of Mineral Resources,CAGS, Beijing 10003.,china 2 Research and Development Center for Saline Lakes and Epithermal Deposits,{3. academy of geological sciences,Beijing 10003.,china 3.Institute of Geology,{3. academy of geological sciences,Beijing 10003.,china 4 Key laboratory of Cenozoic Geology and Environment,{3. academy of sciences,Beijing 100029, china MLR Key laboratory of Saline Lake Resources and Environment Institute of Mineral Resources CAGS Beijing 100037 China Research and Development Center for Saline Lakes and Epithermal Deposits Chinese Academy of Geological Sciences Beijing 100037 China Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China Key laboratory of Cenozoic Geology and Environment Chinese Academy of Sciences Beijing 100029 China

Two sedimentary sections were measured at Tai Co(Co means lake in Tibetan) in western Tibet,*** two sections are almost all composed of clay carbonate beds except in their lower parts where there are carbonized plants at>10 cm depths and dark-colored carbonate clay and clay at 50-70 cm depths,yielding abundant gastropods,ostracods,and *** carbon and oxygen stable isotope values of carbonate,ostracods,and charophytes and ecological features of microfossil communities indicate the following climatic change in the area from 41.4 to 4.5 ka BP:at 41.4-26.2 ka BP,the climate was relatively wet;at 26.2-25.5 ka BP,it was slightly warm-dry;at 25.5-22.5 ka BP,it was warm-wet;at 22.5-21.0 ka BP,it was slightly cold-wet;at 20.5-17.5 ka BP,it became cold abruptly and slightly wet,implying the climate of the last glacial maximum;at 17.5-16.0 ka BP,it was slightly cold-dry;at 16.0-11.8 ka BP,it was slightly warm-wet;at 11.8-10.4 ka BP,it was relatively cold-dry, roughly equivalent to the climate of the Younger Dryas,and at 10.4 ka BP,the temperatures began to rise again;at 10.4-9.4 ka BP,it was slightly warm-wet;at 9.4-8.5 ka BP,there occurred short warm-wet oscillations;at 8.5-7.9 ka BP,it was slightly dry-cold,representing a strong temperature-lowering and drying event in the postglacial stage;at 7.8-6.3.ka BP,it was slightly warm-wet;at 6.3.4.5 ka BP,the climate tended to be cold-dry.4.5 ka BP recorded the maximum aridity since the late part of the late Pleistocene.

关键词： sedimentary environment index paleoclimatic changes late Pleistocene-Holocene(41.4-4.5 ka BP) Tai Co Tibet

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Petrology and mineral chemistry of new ureilites found in Grove Mountains, Antarctica

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Progress in Natural Science:Materials International 2008年第4期18卷 431-439页

作者： Bingkui Miaoa,b,, Yangting Linb, Guiqin Wangc, Daode Wangc, Ziyuan Ouyangd a Key laboratory of geological Engineering Center of Guangxi Province, Guilin University of Technology, Guilin 541004, china b State Key laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, chinese academy of sciences, Beijing 100029, china c Key laboratory of isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, chinese academy of sciences, Guangzhou 510640, chinad National Astronomical Observatories, chinese academy of sciences, Beijing 100012, china Key laboratory of geological Engineering Center of Guangxi Province Guilin University of Technology Guilin 541004 China State Key laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Key laboratory of isotope Geochronology and Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

Petrography and mineral chemistry of two new ureilites, GRV 021512 and 02293., from the Grove Mountains, Antarctica, are reported in this paper. GRV 021512 exhibits a typical ureilite texture, and consists of 48.3. olivine, 9.4% pigeonite and 3..1% carbo- naceous interstitial material and/or reduction product. GRV 02293. has a cataclastic porphyritic texture, and consists of 19.1% olivine and 14.1% pigeonite embedded in 66.3. carbonaceous interstitial material and/or reduction product. The coarse-grained olivine and pigeonite in both meteorites have homogeneous cores, and they are FeO-rich within the range of the ferroan subgroup (subgroup I) of olivine-pigeonite ureilites. All olivine grains of the meteorites show reduction zones along boundaries and cracks. Abundant diamond coexists with graphite as graphite-rich patches and veins in the carbonaceous interstitial material. Petrogenesis of both meteorites and the origin of diamond are discussed.

关键词： Meteorite Achondrite Ureilite Diamond Antarctica

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