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Garnet Sm-Nd and U-Pb systems: A case study of a granulite from the European Variscan belt

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chinese Science Bulletin 2002年第15期47卷 1284-1288页

作者： CHEN FukunInstitut fur Mineralogie, Petrologie und Geochemie, Universitat Tubingen, 72.74.Tubingen, Germany Institute of geology and {2., chinese academy of sciences,{3., China Institut für Mineralogie Petrologie und Geochemie Universität Tübingen Tübingen Germany Institute of geology and geophysics Chinese Academy of Sciences Beijing China

This study presents zircon and garnet ages of a mafic granulite from the high-grade Variscan basement of the Black Forest, Germany and discuss isotope closure temperature of garnet Sm-Nd and U-Pb systems. Zircon grains yield 2.7Pb/2.6Pb ages between -3.2} and -4.4.Ma by the U-Pb and evaporation methods. In contract, garnet dating gives Sm-Nd and Pb-Pb isochron ages of (3.8±3. Ma and (4.1±14. Ma, respectively, which are older than most of zircon ages. These data imply that most of zircons lost radiogenic Pb, probably due to metamictization or recrystallisa-tion during the granulite-facies metamorphism (-800°C) at -3.2} Ma. Garnet Sm-Nd and U-Pb systems preserve chronological information of pro-grade metamorphism, probably profiting from a fluid-absence metamorphic environment. These results demonstrate that garnet mineral can be a better candidate than zircon mineral to date high-grade metamorphism by the U-Pb and Sm-Nd methods in some cases.

关键词： Variscan granulite garnet Sm-Nd U-Pb.

A New SHRIMP Age of the Xiamaling Formation in the North China Plate and Its Geological Significance

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Acta Geologica Sinica(English Edition) 2007年第6期81卷 1103-1109页

作者： GAO Linzhi~(1,*)ZHANG Chuanheng~2.SHI Xiaoying~2.ZHOU Hongrui~2.WANG Ziqiang~2.SONG Biao~(1,3. 1 Institute of geology,chinese {2. of Geological {3.,{4. 10003.,China 2.China University of Geo{3.({4.),{4. 100083.China 3.{4. SHRIMP Central,10003. {4.,China Institute of geology Chinese Academy of Geological Sciences Beijing 100037 China

Setting up the hypostratotype of late Precambrian is the main aim of the research on the Meso-and Neoproterozoic in North *** chronostratigraphic position is the key in this study. However,many key horizons have not been calibrated with the high-quality isotopic *** the reported new U-Pb age with the Sensitive High-Resolution Ion Microprobe（SHRIMPⅡ）,a zircon U- Pb age was obtained of the ash bed in the Xiamaling Formation in North China Plate,yielding a weighted mean;Pb/;U age of 13.8±12.*** is the first SHRIMP U-Pb age from the Xiamaling Formation in the North China Plate,and represents the depositing time of the middle part of the Xiamaling *** zircon age plays an important role to understanding geological evolution of the North China Plate during Meso-and Neoproterozoic.

关键词： SHRIMP U-Pb Dating Mesoproterozoic Xiamaling Formation North China Plate

Helium isotope investigation on magnetic reversal boundaries of loess-paleosol sequence at Luochuan, central chinese Loess Plateau

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chinese Science Bulletin 2007年第17期52卷 2407-2412页

作者： DU XueQing1,6, WANG YongHong2. REN JianGuo3. YE XianRen4.& LU HuaYu5,1 1 State Key Laboratory of Loess and Quaternary geology, Institute of Earth Environment,{2., Xi’an 710075, China 2.College of Marine Geosciences, Ocean University of China, Qingdao 2.6003. China 3.National Natural Science Foundation of China, {3. 100085, China 4.Lanzhou Research Center for Petroleum and Natural Gas Resources, Institute of geology and geophysics,{2., Lanzhou 73.000, China 5 Key Laboratory of Coast and Island Development, School of Geographic and Oceanographic sciences, Nanjing University, Nanjing 2.0093. China 6 Graduate University of{2., {3. 10004., China State Key Laboratory of Loess and Quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi''an 710075 China

Extraterrestrial particles have higher 3.e/4.e ratios than those of terrestrial sediments ( > 100 Ra versus < 0.03.Ra, where Ra is the 3.e/4.e ratio normalized to the atmospheric value of 1.4.10?6). The inter- planet... 详细信息

Extraterrestrial particles have higher 3.e/4.e ratios than those of terrestrial sediments ( > 100 Ra versus 3.Ra, where Ra is the 3.e/4.e ratio normalized to the atmospheric value of 1.4.10?6). The inter- planetary dust particles (IDPs), which are very rich in 3.e, continuously bombard the Earth and can accumulate in deposits. IDPs sedimentation rate changes can significantly influence 3.e concentration in the Earth surface sediments. Since IDPs are not easy to detect in terrestrial deposits, measuring helium isotopes is a helpful approach to examine changes in IDPs. Helium concentration and helium isotopic composition magnetic substances and the quartz particles were examined for helium concen- tration and helium isotopic ratio. Results show that the 3.e/4.e ratio and the 3.e concentrations of the magnetic substances are clearly higher than those of the bulk samples and the quartz particles, and, the 3.e/4.e ratio of the extracted magnetic substances is also higher than that of the average level of the Earth’s crust. The higher helium content in the magnetic fractions can be explained by an influx of IDPs.

关键词：中国黄土高原古土壤氦同位素行星际尘埃颗粒反方向磁化

TAKE ANOTHER VISION TO THE UPLIFT OF THE QING—ZANG (TIBETAN) PLATEAU BASED ON CENOZOIC VOLCANISM

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地学前缘 2000年第S1期7卷 370-371页

作者： Liu Jiaqi [WT5,5”BX](Institute of geology and geophysics,{2. {3. of {4.,beijing 10002., China)

The emergence of the Qing—Zang plateau is among the most important geological events on the globe since the Cenozoic Era. Many geological issues can find answer from here. The major issues concerning plateau probably have three: (1) geodynamics, timing and speed of the plateau uplift;(2. The plateau uplift impact on surrounding environment;(3. mineral resources in the plateau. The authors want to focuses on first issue based on volcanisms occurred in interior and surrounding of the plateau, The new opinions are following:(1) Each volcanic eruptive episode corresponded to strong uplift stage;(2. The dynamic mechanism of the plateau uplift can not ignore another force from west beyond collision between Indian and Eurasia plates from South;(3. The surrounding volcanic chain is not only related to the collision from South, but also from west.

关键词： Tibetan plateau the Cenozoic volcanism volcanic chain surro unding plateau west collision uplift mechanism

FORMATION AND EUOLUTION OF TETHYS IN THE TIBETAN PLATEAU

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地学前缘 2000年第S1期7卷 334-335页

作者： Pan Yusheng[WT5,5”BX](Institute of geology and geophysics,{2.,{3.,China)

The formation of the Tibetan Plateau is closely related to the evolution of Tethys. There have been many researchers and articles concerning the Tethys since *** proposed the concept in 1893. It means a large ocean which lies between Eurasia and Gondwanaland. With the development of Tethyan research, some new terms, appeared such as Neo\|Tethys, Paleo\|Tethys, and Proto\|Tethys, representing the Tethys in Mesozoic—Cenozoic, late Paleozoic and early Paleozoic respectively. The trace of an ocean from Sinian to Ordovician was discovered during the scientific expedition and Proto\|Tethys was proposed to name the ocean. Therefore, the Tibetan Plateau is the main scope of the Eastern Tethys. It can be divided c losely related into three zones which represent the main oceanic locations in th ree different *** Northern Tethyan Region lies in the Kunlun and Qilian Mountains, its remnant is the Fifth Suture Zone. It is also the northern boundary of the Tibetan Plateau The rift initiated after the continental basement had been formed in Sinian and gradually developed into an ocean, which was named Proto\|Tethys, the earliest Tethyan ocean known up to now. The petrochemical compositions of pillow lava in this zone show the characteristics of mid\|ocean ridge tholeiite basalt and the pelagic ophiolitic flysch were well developed, indicating a matured ocean. It was closed in Ordovician and Silurian.

关键词： formation and evolution Tethys Tibetan plateau suture zone structural deformation Gondwana land

Genesis of excess argon in phengite and significance of ^(4.)Ar-^(3.)Ar age spectra for omphacite:A case study on UHP eclogite of South Dabie Terrain,China

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chinese Science Bulletin 2000年第15期45卷 1345-1351页

作者： WANG Songshan, GE Ningjie, SANG Haiqing & QIU Ji1. Institute of geology and geophysics,{2.,{3., China 2. Department of Earth and Space Science, University of Science and Technology of China, Hefei 2.002., China Correspondence should be addressed to Wang Songshan Institute of geology and geophysics Chinese Academy of Sciences Beijing China Department of Earth and Space Science University of Science and Technology of China Hefei China

The Ar-Ar dating of phengite and omphacite in ultrahigh-pressure (UHP) eclogite of Bixiling and Hengchong in the South Dabie Terrain shows that the content range of excess argon is as high as (0.4.1.3.×10 8 mol· g 1. The genesis of the excess argon is discussed. The Ar-Ar age spectra of omphacite could not support the opinion that the UHP metamorphism occurred in Caledon epoch and pre-Caledon epoch.

关键词： South Dabie Terrain ultrahigh-pressure metamorphics phengite omphacite excess argon.

Origin of a native sulfur chimney in the Kueishantao hydrothermal field, offshore northeast Taiwan

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Science China Earth sciences 2007年第11期50卷 1746-1753页

作者： ZENG ZhiGang1, LIU ChangHua1,2. CHEN ChenTung A3. YIN XueBo1, CHEN DaiGeng1,2. WANG XiaoYuan1,2. WANG XiaoMei1,2.& ZHANG GuoLiang1,2.1 Seafloor Hydrothermal Activity Laboratory of the Key Laboratory of Marine geology and Environment, Institute of Oceanology, chinese academy of sciences, Qingdao 2.6071, China 2.Graduate University of chinese academy of sciences, {3. 10004., China 3.Institute of Marine geology and Chemistry, National Sun Yat-Sen University, Kaohsiung 804. Taiwan, China 1. Seafloor Hydrothermal Activity Laboratory of the Key Laboratory of Marine geology and Environment Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China 2. Graduate University of chinese academy of sciences Beijing 100049 China 3. Institute of Marine geology and Chemistry National Sun Yat-Sen University Kaohsiung 804 Taiwan China

Analyses of rare earth and trace element concentrations of native sulfur samples from the Kueishantao hydrothermal field were performed at the Seafloor Hydrothermal Activity Laboratory of the Key Labo-ratory of Marine geology and Environment, Institute of Oceanology, chinese academy of sciences. Using an Elan DRC II ICP-MS, and combining the sulfur isotopic compositions of native sulfur samples, we studied the sources and formation of a native sulfur chimney. The results show, when comparing them with native sulfur from crater lakes and other volcanic areas, that the native sulfur content of this chimney is very high (99.96%), the rare earth element (REE) and trace element constituents of the chimney are very low (ΣREE2.×10?9), and the chondrite-normalized REE patterns of the native sulfur samples are similar to those of the Kueishantao andesite, implying that the interaction of subseafloor fluid-andesite at the Kueishantao hydrothermal field was of short duration. The sulfur isotopic compo-sitions of the native sulfur samples reveal that the sulfur of the chimney, from H2. and SO2. originated by magmatic degassing and that the REEs and trace elements are mostly from the Kueishantao ande-site and partly from seawater. Combining these results with an analysis of the thermodynamics, it is clear that from the relatively low temperature (<116 ℃ ), the oxygenated and acidic environment is favorable for formation of this native sulfur chimney in the Kueishantao hydrothermal field.

关键词： origin,native sulfur chimney,Kueishantao hydrothermal field,northeast Taiwan

Elemental and isotopic compositions of the hydrothermal sulfide on the East Pacific Rise near 13.N

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Science China Earth sciences 2010年第2期53卷 253-266页

作者： ZENG ZhiGang1,CHEN DaiGeng1,2.YIN XueBo1,WANG XiaoYuan1,ZHANG GuoLiang1,2.& WANG XiaoMei1,2.1 Seafloor Hydrothermal Activity Laboratory of the Key Laboratory of Marine {3. and Environment,Institute of Oceanology,chinese {2. of {3.,Qingdao 2.6071,China 2.Graduate School of{4.,beijing 10004.,China 1. Seafloor Hydrothermal Activity Laboratory of the Key Laboratory of Marine geology and Environment Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China2. Graduate School of Chinese Academy of Sciences Beijing 100049 China

The mineralogical,elemental,and isotopic characteristics of a hydrothermal sulfide sample from one dredge station (12.4..3.’N,103.54.4.’W,water depth 2.55 m) on the East Pacific Rise near 13.N were *** hydrothermal sulfide was composed mainly of sphalerite,chalcopyrite,and pyrite and was a Zn-rich sulfide;in layer ep-s-1,goethite formed by secondary oxidation was *** concentrations of rare elements,such as Li (0.15×10-6-0.3.×10-6),Be (0.01×10-6-0.05×10-6),Zr (73.8×10-9-13.1}×10-9),Nb (8.14.10-9-64.7×10-9),Hf (2.54.10-9-2..0×10-9),and Ta (0.2.3.10-9-1.2.×10-9),were far lower in the hydrothermal sulfide than in the ocean crust,whereas the content of Au was higher and the contents of Co,Ni,Sr,Cs,Ba,Bi,and U were *** correlations between Zn and Cr,Cd and Ga,Cu and P,P and In (R2.> 0.8) were positive,whereas those between Zn and Fe,Cu,and Ba (R2.> 0.8) were distinctly *** low-temperature mineral assemblages to high-temperature mineral assemblages,the spatial distributions of dispersive and rare elements (***,Li,Cs) in the hydrothermal sulfide displayed corresponding *** variations observed in some elements (e.g.,Cd,Cs,P) are controlled by Zn,Fe,and Cu sulfides,*** weathering accounts for the enrichment of V,Mn,and rare earth elements (REE) in the henna sulfide-oxidation layer that bears the secondary oxide mineral,leading to identical REE patterns for this layer (ep-s-1) and *** weathering also distinctly affects the correlations between the element ratios of the hydrothermal *** high-temperature mineral assemblages to low-temperature mineral assemblages,Fe content and δ 3.1} value of the hydrothermal sulfide increase gradually,and Zn content and lead isotopic ratios decrease gradually on the contrary,which indicate the influences of seawater on elements and the sulfur and lead isotopic compositions enhance gradually during the formation of hydrothermal sulfides.

关键词： variation element isotopic composition hydrothermal sulfide East Pacific Rise 13.N

Modern microbialites and their environmental signifi-cance,Meiji reef atoll,Nansha (Spratly) Islands,South China Sea

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Science China Earth sciences 2008年第4期51卷 608-617页

作者： SHEN JianWei1 & WANG Yue1,2.1 Department of Marine geology, South China Sea Institute of Oceanology Key Laboratory of Marginal Sea geology, South China Sea Institute of Oceanology and Guangzhou Institute of Geochemistry,{2., Guangzhou 5103.1, China 2.Graduate University of the{2., {4. 10004., China Department of Marine geology South China Sea Institute of Oceanology Guangzhou China Key Laboratory of Marginal Sea geology South China Sea Institute of Oceanology and Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou

Meiji (Mischief) coral atoll, in Nansha (Spratly) Islands, South China Sea, consists of an annular reef rim surrounding a central lagoon. On the atoll rim there are either protuberant 'motu' (small coral patch reefs on the rim of atoll) islets or lower sandy cays that contain modern microbialite deposits on the corals in pinnacles and surrounding bottoms of the atoll. Microbialites, including villiform, hairy, and thin spine growth forms, as well as gelatinous masses, mats and encrustation, developed on coral colonies and atoll rim sediments between 0 and 15 m deep-water settings. The microbialites were produced by natural populations of filamentous cyanobacteria and grew on (1) bulbous corals together with Acropora sp., (2. on massive colonies of Galaxea fascicularis, (3. on dead Montipora digitata, and (4. on dead Acropora teres, some hairy microbialite growing around broken coral branches. This study demonstrates that microbial carbonates are developed in coral reefs of South China Sea and indicates that microbial processes may be important in the construction of modern reef systems. The results have significance in the determination of nature and composition in microorganisms implied in the formation ancient microbialites, and permit evaluation of the importance of microbial deposits in mo-dern coral reefs and of 'microbialites' in biogeochemical cycles of modern coral reef systems. The re-sults also provide evidence of modern analogues for ancient microbialites in shallow-water settings, and combine with sedimentological studies of ancient microbialites to understand their controls.

关键词： Microbialite Meiji reef Nansha Island South China Sea