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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 {2. institute of Oceanology key laboratory of marginal {2. geology, South china {2. institute of Oceanology and{12., chinese academy of sciences, guangzhou 510301, china 2.Graduate University of the chinese academy of sciences, Beijing 100049, china Department of Marine geology South China Sea Institute of Oceanology Guangzhou China key laboratory of {2. sea geology South China Sea Institute of Oceanology and Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Graduate University of the chinese academy of sciences Beijing China

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

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Magnetic properties of Jiaxian red clay sequences from northern chinese Loess Plateau and its paleoclimatic significance

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Science china Earth sciences 2005年第8期48卷 1234-1245页

作者： QIANG Xiaoke, AN Zhisheng, LI Huamei, CHANG Hong & SONG Yougui 1. SKLLQG, institute of Earth Environment, chinese academy of sciences, Xi’an 710075,{2. 2. guangzhou institute of geochemistry, chinese academy of sciences, guangzhou 51064.,{2. chinese academy of {2. SKLLQG Institute of Earth Environment Xi’an China chinese academy of {2. Guangzhou Institute of Geochemistry Guangzhou China

Detailed rock magnetism investigation of the Jiaxian red clay sequences indicated that there are common magnetic mineralogy properties in red clay and loess-paleosol sequences from the chinese Loess Plateau as well as the marked properties of themselves, magnetic min-erals mainly with magnetite, maghemite, hematite, and possibly limonite/goethite contributing to the magnetic behavior. Meanwhile, it is found that the strong paleosol in red clay sequences has a lower coercivity and higher content of ultra-fine ferrimagnetic grains than that of the weak pa-leosol, which is similar to loess and paleosol in upper Wucheng Loess sequences, and indicates that humid conditions and relatively strong pedogenesis play a significant role in the increase of ultra-fine magnetic minerals and transformation of the magnetic minerals. This suggests that, like Quaternary loess-paleosols, the change of characteristics of paleoclimatic conditions of the late Tertiary red clay deposits is fluctuant. In addition, the results of magnetic hysteresis properties show that the applied saturated field for samples from the Jiaxian red clay sequences is higher than that of the samples from eastern and southern chinese Loess Plateau. It is obviously shown that there exist more hard magnetic minerals and relatively weak biochemical processes in the Jiaxian red clay sequences on northern chinese Loess Plateau. We conclude that the paleocli-matic environment is different between northern and eastern/southern chinese Loess Plateau, and it should be more arid in northern chinese Loess Plateau.

关键词： northern chinese Loess Plateau, red clay, magnetic property, paleoclimatic significance.

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Research on the dynamics of the South china sea opening:Evidence from analogue modeling

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Science china Earth sciences 2006年第10期49卷 1053-1069页

作者： SUN Zhen1,2, ZHOU Di1, ZHONG Zhihong3, XIA Bin2, QIU Xuelin1, ZENG Zuoxun4 & JIANG Jianqun5 1. cas key laboratory of marginal sea geology, South china sea institute of Oceanology, chinese academy of sciences, guangzhou 510301, china 2. cas key laboratory of marginal sea geology, guangzhou institute of geochemistry, chinese academy of sciences, guangzhou 51064., china 3. Department of Technology, Shenzhen Branch of CNOOC, guangzhou 510240, china 4. Faculty of Earth sciences, china University of Geosciences, Wuhan 430074, china 5. Hainan Oil & Gas Exploration Company, Liaohe Oilfield Petrochina, Panjin 124010, china cas key {2. of marginal sea geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China cas key {2. of marginal sea geology Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Department of Technology Shenzhen Branch of CNOOC Guangzhou China Faculty of Earth sciences China University of Geosciences Wuhan China Hainan Oil & Gas Exploration Company Liaohe Oilfield PetroChina Panjin China

Independent of Indochina extrusion, the South china {2. experienced a process from passive continental rifting to marginal {2. drifting. According to the fault patterns in the Beibu Gulf basin and the Pearl River Mouth basin, the continental rifting and early spreading stage from 32.to 2. Ma were controlled by extensional stress field, which shifted clockwise from southeastward to south southeastward. From 2. Ma on, the {2. spread in NW-SE direction and ceased spreading at around 15.5 Ma. Integrated geological information with the assumption that the South china {2. developed along a pre-Cenozoic weakness zone, we did analogue experiments on the South china {2. evolu- tion. Experiments revealed that the pre-existing weakness zone goes roughly along the uplift zone between the present Zhu-1 and Zhu-2.depression. The pre-existing weakness zone is composed of three segments trending NNE, roughly EW and NEE, respectively. The early opening of the South china {2. is accompanied with roughly 15° clockwise rotation, while the SE sub-{2. basin opened with SE extension. Tinjar fault was the western boundary of the Nansha block (Dangerous Ground), while Lupar fault was the eastern boundary of the Indochina, NW-trending rift belt known as Zengmu basin developed between above two faults due to block divergent of Indochina from Nansha. In the experiment, transtensional flower structures along NW-trending faults are seen, and slight inversion occurs along some NE-dipping faults. The existence of rigid massifs changed the orientations of some faults and rift belt, and also led to deformation concentrate around the massifs. The rifting and drifting of the South china {2. might be caused by slab pull from the proto South china {2. subducting toward Borneo and/or mantle flow caused by India-Asia collision.

关键词： South china sea, rifting and drifting, clockwise rotation, analogue modeling, rigid massifs.

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Assessment of coral bleaching using symbiotic zooxanthellae density and satellite remote sensing data in the Nansha Islands,South china sea

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chinese Science Bulletin 2011年第10期56卷 1031-1037页

作者： LI Shu,YU KeFu,CHEN TianRan,SHI Qi & ZHANG HuiLing cas key {2. of marginal sea geology,South china sea institute of Oceanology,chinese academy of sciences {12. 510301,china cas key {2. of marginal sea geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China

Coral bleaching,characterized by a significant loss of symbiotic zooxanthellae,is the primary cause of mass coral mortality and reef degradation throughout the *** characteristics,processes,and resistance of corals to bleaching varies significantly and is dependent on environmental *** documented a mass coral bleaching event in June 2.07 at the Meiji and Zhubi Reefs,Nansha Islands (NS),South china sea using ecological surveys and measurement of coral zooxanthellae density and sea surface temperatures (SST).More than 35 species of corals (between 0-2. m in depth) were *** bleached corals accounted for 15.6% of total corals in the investigated *** branching corals Pocillopora and Acropora were the most vulnerable species whereas the massive corals Porites and Favia were more tolerant of the high ***,we found no evidence of bleaching in Agariciidae corals suggesting that this family is resistant to thermal *** bleached corals had lost 72.-90% of their symbiotic ***,corals that had no visual signs of bleaching had also lost 31%-53% of their zooxanthellae suggesting that most corals were experiencing the early stage of *** monthly mean SST during June 2.07 was 30.8°C,the highest since *** on measurements of SST and the Hotspots and DHW data (NOAA),we conclude that it the extremely high SSTs triggered this coral bleaching *** results suggest that the previously accepted temperature thresholds used to predict coral bleaching based on satellite data are likely to underestimate the extent and intensity of coral bleaching,at least in the NS.

关键词：珊瑚礁南沙群岛中国南海卫星遥感数据漂白黄藻密度共生

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Identification and analysis of shear waves recorded by three-component OBSs in northeastern South china sea

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Progress in Natural Science:Materials International 2008年第2期18卷 181-188页

作者： Minghui Zhao ,Xuelin Qiu,Shaohong Xia,Ping Wang,Kanyuan Xia,Huilong Xu key laboratory of {2. sea geology,South china sea institute of Oceanology,chinese academy of sciences,guangzhou 510301,{12. key laboratory of {2. sea geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China

Structure models associated with P-and S-wave velocities contain considerable amount of information on lithology and geophysical properties,which can be used to better understand the complexity of the deep crustal structure. However,records of converted shear waves are less due to the speciality of seismic survey at sea and the rigorous generated conditions. The study on shear waves has always been a weakness for studying the deep crustal structures of South china sea (SCS). In this paper,eleven three-component OBSs were deployed along the Profile OBS-2.01 in northeastern SCS. After the data processing of polarization and band-pass filter,converted S-wave phases were identified in the radical component records of nine OBSs. Taking the OBS7 as an example,identification and analysis of converted shear waves were presented and discussed in detail. A few phase groups,such as PwSc,PgSs,PnSc,PmS,and PwSn,were found coming from the deep crust or Moho interface by simple theoretical model calculation and ray-tracing simulation. The results not only provide the underlying basis for studies of S-wave velocity structure and Poisson’s ratio structure,but also reveal the relationship between crustal petrology and seismology,which will be of importance for making full use of S-wave information in the future.

关键词： Converted shear wave Deep crustal structure Three-component ocean bottom seismometer Northeastern South china sea

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Discovery of seep carbonate nodules as new evidence for gas venting on the northern continental slope of South china sea

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chinese Science Bulletin 2006年第10期51卷 1228-1237页

作者： CHEN Zhong1,2,3, YAN Wen1,2,3, CHEN Muhong1,3, WANG Shuhong1,2,3, LU Jun1,3, ZHANG Fan1,3, XIANG Rong1,3, XIAO Shangbin1,3, YAN Pin1,2,3 & GU Senchang1,2,3 1. South china sea institute of Oceanology, chinese academy of Sci-ences, guangzhou 510301, china 2. guangzhou Center for Gas Hydrate Research, chinese academy of sciences, guangzhou 510301, china 3. key laboratory of marginal sea geology, South china sea institute of Oceanology and guangzhou institute of geochemistry, chinese academy of sciences, guangzhou 510301, china South china sea {2. of Oceanology Chinese Academy of Sciences Guangzhou China guangzhou Center for Gas Hydrate Research Chinese Academy of Sciences Guangzhou China key laboratory of {2. sea geology South China Sea Institute of Oceanology and Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China

Seep carbonate nodules were firstlycollected from the southwestern Dongsha area onnorthern continental slope of South china sea formineralogical and geochemical studies. The resultsof X-ray diffraction show that carbonate nodules arecomposed of Fe-rich domolite,siderite and a few cal-cite and aragonite, as well as a small quantity ofnon-carbonate minerals such as goethite, quartz andclay minerals. Fe-rich dolomite and siderite charac-terized by euhedral microcrystalline structure weredirectly precipitated at cold seeps. The δ 13C valuesfor Fe-rich dolomite and siderite in the bulk nodulesvary from ?18.2.‰ to ?36.07‰, and the δ 18O valuesrange from 0.42.to 2.76‰. Their moderate depleted13C reflects that carbon origin is possibly thermoge- netic gas or mixed gas, which is evidence of gasventings in the seafloor. Moreover, massive wormtube fossils related to cold seeps were found on thesurfaces of carbonate nodules, and the conduitsand/or channels in semi-solidified nodules whichwere not filled by carbonate or sediment were alsoobserved. A preliminary conclusion is that activemicro gas venting with a conduit/channel diameterrange from 2.0 μm to 600 μm possibly exists inmodern seafloor of the carbonate nodule area.

关键词：渗出碳酸盐节碳氧同位素甲烷渗漏天然气水化物

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The biomarkers of 2.6,10,15, 19-pentamethylicosenes and their carbon isotopic composition in the sediments from the Gulf of Mexico

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chinese Science Bulletin 2006年第14期51卷 1736-1740页

作者： SONG Zhiguang1,2.& WANG Cuiping1,31. State key laboratory of Organic {2., guangzhou institute of geochemistry, chinese academy of sciences, guangzhou 51064., china 2. guangzhou Research Center of Gas Hydrate, chinese academy of sciences, guangzhou 51064., china 3. Graduate School of chinese academy of sciences, Beijing 100039, china State key laboratory of Organic {2. Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China guangzhou Research Center of Gas Hydrate Chinese Academy of Sciences Guangzhou China Graduate School of chinese academy of sciences Beijing China

A group of 2.6,10,15,19-pentamethyli- cosenes (PMIΔ) containing 1―5 unsaturated double bonds has been identified in the sea floor sediments from the Gulf of Mexico at the Green Canyon 2.8 *** PMIΔ compounds are distributed between nC2. and nC2. on the mass chromatogram of aliphatic fraction. Their δ 13C values are very much depleted in 13C and in the range of ?86.7‰ to ?115.5‰, whereas the δ 13C values of companion n-alkanes range from ?2..4‰ to ?34.6‰. These unsaturated PMIΔ com-pounds are typical biomarkers derived from the an-aerobic oxidation of methane mediated by meth-ane-oxidizing archaeal bacteria and indicative of the gas seeps or even the occurrence of gas hydrates in the deep sea sediments.

关键词：生物标志墨西哥湾沉积物 PMIA 天然气水化物

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Ecological-sedimentary zonations and carbonate deposition,Xiaodonghai Reef Flat,Sanya,Hainan Island,china

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Science china Earth sciences 2011年第3期54卷 359-371页

作者： WANG Yue1,2. SHEN JianWei1 & LONG JiangPing3 1 Department of Marine geology, South china {2. institute of Oceanology cas key laboratory of marginal {2. geology, South china {2. institute of Oceanology, chinese academy of sciences, guangzhou 510301, china 2.Graduate University of chinese academy of sciences, Beijing 100049, china 3 The Second Institution of Oceanography, State Oceanic Administration, Hangzhou 310012. china Department of Marine geology South China Sea Institute of Oceanology Guangzhou China Graduate University of chinese academy of sciences Beijing China cas key {2. of marginal sea geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China The Second Institution of Oceanography State Oceanic Administration Hangzhou China

Modern fringing reefs are developed on the intertidal to subtidal area of Xiaodonghai bay, Sanya, Hainan Island. The reef flat extends several dozen meters toward the sea. Various ecological and sedimentary zonations can be distinguished, including, from land to sea, beachrocks, large massive corals, inner reef flat, outer reef flat, and fore-reef slope. The carbonate sediments and constituent hermatypic coral communities are different in these zones. The beachrocks are composed mainly of biological sands, including coral skeletons, algae, gastropods, bivalves, and benthic foraminifera. Quartz sands are less common in this zone. Carbonate diagenesis in beachrocks is characterized by early cementation. The fringing reef flat is progradationally developed toward the sea. Large massive corals grew in the zone next to the beachrocks. These corals are large, flat-toped, and autochthonous in the production of bioclastic grains and lime mud. Large and massive coral skeletons are surrounded by coral skeletal grains, bioclasts, and lime-mud sediments. The inner reef flat consists mainly of skeletons of branching corals that are covered by bioclasts and lime mud, and living corals are mostly massive in form. Statistical analysis of coral-community dynamics shows that the outer reef flat with strong waves is the most suitable place for hermatypic corals to flourish. There, the living corals are most densely distributed. Both massive corals and branching corals (e.g., Acropora corymbosa) are exceptionally healthy in this zone. Bioclasts and lime mud are washed out due to strong wave action. Microbial carbonates generally are deposited within cavities of the beachrocks and coral skeletal cavities and on the surfaces of bioclastic grains. The latter two types, however, are more common. Ecological-sedimentary zonations across the Xiaodonghai reef flat from beachrocks to outer reef flat are controlled by variations in wave strength and water energy. Microbial carbonates rarely deve

关键词： microbial carbonates ecological-sedimentary zonation cementation reef flat Hainan Island

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Late Neogene radiolarian absence event in the southern South china sea and its paleoceanographic implication

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Progress in Natural Science:Materials International 2008年第3期18卷 281-287页

作者： Lili Zhanga,b, Muhong Chena, Lanlan Zhanga,b, Jun Lua, Rong Xianga a key laboratory of {2. sea geology, South china sea institute of Oceanology, chinese academy of sciences, guangzhou 510301, china b Graduate University of chinese academy of sciences, Beijing 100039, china key laboratory of {2. sea geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China Graduate University of chinese academy of sciences Beijing 100039 China

Down-core variations of radiolarians at ODP Site 1143 in the southern South china sea (SCS) are presented for the last 12.Myr. The fluctuations of radiolarian abundances since the Late Miocene can be divided into three stages: a high abundance stage at 12.5.96 Myr, a radiolarian absent stage at 5.96-3.30 Myr and a gradual increasing stage after 3.30 Myr. The three stages correspond to the forming and vicissitudes of the Western Pacific Warm Pool (WPWP) and the Eastern Asian Summer Monsoon (EASM). The radiolarian absence event (RAE) was also absent of diatom and occurred nearly simultaneously with the closures of the Panama Isthmus and the Indonesian seaway, which probably caused the reorganization of oceanic circulation systems. Accompanied this circulation reorganization was the weakening of the WPWP and the EASM, which probably led to a weakened upwelling in the southern SCS. In addition dissolved silica (Dsi) content in surface seawater might be very low during 5.96-3.30 Myr due to the ’’biogenic bloom" event, which consumed a large amount of Dsi in the surface seawater. All these factors together might lead to a great decrease of siliceous production in the southern SCS and consequently caused the RAE. Moreover, the dissolution of siliceous skeletons might also influence the abundance of radiolarians.

关键词： Southern South china sea Late Neogene Radiolarian absence event

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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,{2. b State key laboratory of Lithospheric Evolution, institute of geology and Geophysics, chinese academy of sciences, Beijing 10002.,{2. c key laboratory of Isotope Geochronology and geochemistry,{12., chinese academy of sciences, guangzhou 51064.,{2.d National Astronomical Observatories, chinese academy of sciences, Beijing 100012.{2. 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 {2. 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 02.512.and 02.931, from the Grove Mountains, Antarctica, are reported in this paper. GRV 02.512.exhibits a typical ureilite texture, and consists of 48.3% olivine, 9.4% pigeonite and 38.1% carbo- naceous interstitial material and/or reduction product. GRV 02.931 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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