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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 510640,{2. 1. chinese academy of sciences SKLLQG Institute of Earth Environment 710075 Xi’an China 2. chinese academy of sciences Guangzhou Institute of Geochemistry 510640 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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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 Guangzhou institute of geochemistry, 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

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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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 510640, 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 1. cas key {2. 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 510640 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

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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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 {2. 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 {2. of Oceanology and Guangzhou {2. of geochemistry, chinese academy of sciences, Guangzhou 510301, china South china sea {2. of Oceanology Chinese Academy of Science Guangzhou China Guangzhou Center for Gas Hydrate Research Chinese Academy of Sciences Guanzhou 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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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 1. Department of Marine geology South China Sea Institute of Oceanology Guangzhou China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China4. CAS Key Laboratory of Marginal Sea Geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China3. The Second Institution of Oceanography State Oceanic Administration Hangzhou 310012 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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Paleoenvironments indicated by the fossil mammalian assemblages from red clay-loess sequence in the chinese Loess Plateau since 8.0 Ma B.P.

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Science china Earth sciences 2006年第5期49卷 518-530页

作者： XUE Xiangxu1,2. ZHANG Yunxiang1,2.& YUE Leping1,2.1. State key laboratory of Continent Dynamics (Northwest University), {2. of Cenozoic geology and Environment, De- partment of geology, Northwest University, Xi’an 710069, china 2. {2. of Earth Environment, State key laboratory of Loess and Quaternary geology, chinese academy of sciences, Xi’an 710075, china 1. State key laboratory of Continent Dynamics (Northwest University) Institute of Cenozoic Geology and Environment Department of Geology Northwest University Xi’an 710069 China 2. institute of Earth Environment State Key Laboratory of Loess and Quaternary Geology Chinese Academy of Sciences Xi’an 710075 China

Information from eleven profiles of eolian earthy red silty clay and loess of the middle of the Late Miocene to Holocene age have been studied and correlated. A complete summary profile with projected isotopic ages and fossil-bearing beds has been assembled. The profile is subdivided into 12.stratigraphic units proceeding from the lower (older) to the upper (younger) one. The character of mammalian assemblages contained in each unit was analyzed and the corresponding pa- leo-climatic environments were deduced. The environmental character of each period and the change from the middle of the Late Miocene at about 8.0 Ma B.P. up to the Holocene progressed from the hot semiarid and semi-moist, warmer-moist, warm-moister of the Late Miocene. To slightly less warm moist, cool-dry, slight-warmer-moister of the Pliocene; later the cool to cold dry periods alternated frequently with the mild semiarid and semi-moist periods of the Quaternary. Vegetation progressed from the grasslands with sparse woods, wooded shrub-grasslands and subtropical forest-grasslands of the Late Miocene age to sparse grasslands and dry grasslands of the Pliocene; and to sparse grasslands, dry grasslands and tundras of the Quaternary. The climate changes in the Neogene were of low-amplitute in a generally warm-humid background. Those of the Quaternary were of higher am- plitude with a longer phase. Cool or cold dry and slightly warm semiarid and semi-moist climates al- ternated on a generally cool-dry background. The tendency since the start of the Quaternary was the change to more northern and western shift in the Loess Plateau, with progressively cooler and dryer conditions. The dramatic uplift of the Qinghai-Xizang (Tibet) Plateau and the forming and expansion of the Arctic ice sheet might be the main reasons of the more pronounced changes in the Quaternary.

关键词： paleoenvironment, mammalian fossils, eolian red clay-loess sequence, Loess Plateau.

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Digital image analysis of palaeoenvironmental records and applications

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chinese Science Bulletin 2002年第23期47卷 1957-1963,2025-2026页

作者： SUN Donghuai1,2. LIU Yu2.& TAN Ming31. South china sea {2. of Oceanology, chinese academy of sciences. Guangzhou 510301, china 2. State key laboratory of Loess and Quaternary geology, Earth Environmental {2., chinese academy of sciences, Xi’an 710075, china 3. {2. of geology and Geophysics, chinese academy of sciences, Beijing 10002., china South china sea {2. of Oceanology Chinese Academy of Sciences Guangzhou China State key laboratory of Loess and Quaternary {2. Earth Environmental Institute Chinese Academy of Sciences Xi’an China institute of geology and Geophysics Chinese Academy of Sciences Beijing China

Environmental change signals in geological or biological records are commonly reflected on their reflecting or transmitting images. These environmental signals can be extracted through digital image analysis. The analysis principle involves section line selection, color value reading and calculating environmental proxy index along the section lines, layer identification, auto-chronology and investigation of structure evolution of growth bands. On detailed illustrations of the image technique, this note provides image analyzing procedures of coral, tree-ring and stalagmite records. The environmental implications of the proxy index from image analysis are accordingly given through application demonstration of the image technique.

关键词： digital image environmental records.

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Forcing mechanism of the Pleistocene east Asian monsoon variations in a phase perspective

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Science china Earth sciences 2005年第10期48卷 1708-1717页

作者： TIAN Jun1,2. WANG Pinxian1, CHENG Xinrong1, WANG Rujian1 & SUN Xiangjun1,3 1. State key laboratory of Marine {2., Tongji University, Shanghai 2.0092. china 2. institute of {2. and Geophysics, chinese academy of sciences, Beijing 10002., china 3. institute of Botany, chinese academy of sciences, Beijing 100093, china State key laboratory of Marine {2. Tongji University Shanghai china institute of geology and Geophysics{2. Beijing china institute of Botany chinese academy of sciences Beijing{2.

The deep sea records from the ODP Sites 1143 and 1144 in the northern and southern South china sea (SCS), including foraminiferal δ 18O and δ 13C, Opal% and pollen percentage, reveal that the variations of the east Asian monsoon have been closely correlated with the variations of the Earth’s orbital parameters (eccentricity, obliquity and precession) and the global ice volume on orbital scale. All the monsoonal proxies show strong 100 ka, 41 ka and 2. ka cycles. Although G. ruber δ 13C of Site 1143 is coherent with the ETP (ETP= normalized (eccentricity + obliquity-precession) at eccentricity, obliquity and precession bands, most of the coherent relationship focuses on the precession band, and the other monsoonal proxies are coherent with the ETP only at the precession band, which indicate that precession dominates the Pleistocene tropical climate changes. The phase relationship of the monsoonal proxies with the foraminiferal δ 18O implies that the global ice volume changes have played a significant role in modulating the east Asian monsoon climate, at least dominating the winter monsoon. This forcing mechanism of the east Asian monsoon is apparently different from that of the Indian ocean mon-soon. The variations of the east Asian monsoon at the precession band, at least that of the winter monsoon, have been controlled not only by the sensible heating but also by the latent heating of the surface water in the South china sea.

关键词： South china sea, ODP, east Asian monsoon, orbital forcing, global ice volume.

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Zircon SHRIMP U-Pb geochronology and petrogenesis of the plagiogranites from the Lagkor Lake ophiolite,Gerze,Tibet,china

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chinese Science Bulletin 2007年第5期52卷 651-659页

作者： ZHANG YuXiu1,2. ZHANG KaiJun1,3, LI Bing1,2. WANG Yang1,2. WEI QingGuo1,2.& TANG XianChun1,2.1 key laboratory of {2. sea geology, Guangzhou institute of geochemistry, chinese academy of sciences, Guangzhou 510640, china 2.Graduate University, chinese academy of sciences, Beijing 100039, china 3 Department of Earth {12., Nanjing University, Nanjing 2.0093, china key laboratory of {2. sea geology Guangzhou Institute of GeochemistryChinese Academy of Sciences Guangzhou 510640 China

地关系与 petrographical 一起， petrological ，和 geochemicalcharacteristics ，和锆石人口，显示从在 Bangong-Nujiang 缝术地区的 Lagkor Lakeophiolite 的 plagiogranites (～ Gerze 县的 2. km 南方，中央西藏，中国)，由在海洋的外壳的运输期间的可锻的砍源于含水的斑粝岩的 anatexis 。因此，这种 plagiogranite 比传播海洋的外壳晚对或很少同时代。锆石虾 166 ±使 2.5 妈变老因为 plagiogranites 显示海洋的盆在中间的侏罗记在 Bangong-Nujiang 地区的西方的部分存在。

关键词：西藏改则县拉果错湖泊蛇绿岩斜长花岗岩锆SHRIMP U-Pb地质年代岩石成因

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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 Guangzhou 510301,{12. 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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