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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 {3. 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 {3. of oceanology Chinese Academy of Sciences Guangzhou China guangzhou Center for Gas Hydrate Research Chinese Academy of Sciences Guangzhou China key laboratory of marginal {3. 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 {3. 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 13. valuesfor Fe-rich dolomite and siderite in the bulk nodulesvary from ?18.24‰ to ?3..07‰, and the δ 18O valuesrange from 0.42 to 2.76‰. Their moderate depleted13. reflects that carbon origin is possibly thermoge- netic gas or mixed gas, which is evidence of gasventings in the {3.floor. 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 200 μm to 600 μm possibly exists inmodern {3.floor 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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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 {3. institute of oceanology key laboratory of marginal {3. geology, south china sea institute of oceanology and guangzhou institute of geochemistry, chinese academy of sciences,{13., 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 marginal {3. 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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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 marginal {3. geology,south china {3. institute of oceanology,chinese academy of sciences,{13. 510301,china key laboratory of marginal {3. 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-2001 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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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 laboratory of marginal {3. geology,south china {3. institute of oceanology,chinese academy of sciences {13. 510301,china CAS key laboratory of marginal {3. 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 2007 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 3. species of corals (between 0-20 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 3.%-53. of their zooxanthellae suggesting that most corals were experiencing the early stage of *** monthly mean SST during June 2007 was 3..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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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 {3. institute of oceanology CAS key laboratory of marginal {3. geology, south china {3. 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 3.0012, china Department of Marine geology South China Sea Institute of Oceanology Guangzhou China Graduate University of chinese academy of sciences Beijing China CAS key laboratory of marginal {3. 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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Youger Dryas and Heinrich events recorded by magnetic susceptibility of sediments from the central temperature area of Western Pacific Warm Pool

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chinese Science Bulletin 2003年第8期48卷 808-813页

作者： TANG Xianzan, CHEN Zhong,YAN Wen & CHEN Muhong The Open laboratory of geology and Paleoenvironment of marginal {3., south china {3. institute of oceanology, chinese academy of sciences, guangzhou 510301, china Open laboratory of geology and Paleoenvironment of marginal {3. South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China

Three short geomagnetic excursions, the Go thenburg, Mono Lake and Mungo (or Maelifell) in the Brunhes Positive Polarity period, were revealed based on the studies of magnetostratigraphy, susceptibility (c) and d 18O of sediments in core WP 92-5 from the central temperature area of the Western Pacific Warm Pool (WPWP), and the ages of them are 12.111.3.kaBP, 25.024.0 kaBP, and 3..028.0 kaBP respectively. Furthermore, the Younger Dryas (YD) and Heinrich (H) cold events were also discov- ered in this core by the susceptibility record. The YD cold event occurred at the depth of 3.22 cm with an age of 11.510.6 kaBP; H1, H2 and H3.cold events occurred at depths of 513. cm, 10891 cm and 140126 cm with ages of 15.113.0 kaBP, 25.022.1 kaBP and 3..628.2 kaBP respectively, which well correspond to the H1, H2, H3.events recorded by susceptibility of core SU90-09 from middle At- lantic, indicating that the susceptibility change of marine sediments can be an important sign of climatic frequent fluc- tuations.

关键词：磁化率沉积物西太平洋磁性地层学

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Late Neogene radiolarian absence event in the southern south china {3. 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 marginal {3. geology, south china {3. institute of oceanology, chinese academy of sciences, guangzhou 510301, china b Graduate University of chinese academy of sciences, Beijing 10003., china key laboratory of marginal {3. 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 {3. (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 5.96-3.3. Myr and a gradual increasing stage after 3.3. 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 {3.way, 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 {3.water might be very low during 5.96-3.3. Myr due to the ’’biogenic bloom" event, which consumed a large amount of Dsi in the surface {3.water. 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 {3. Late Neogene Radiolarian absence event

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A preliminary analysis on lithospheric thickness and crustal ages in central basin of south china sea

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Acta Oceanologica Sinica 1997年第1期16卷 85-107页

作者： Chen Xue and Lin Jinfeng south china sea {3. of oceanology, the chinese academy of sciences, guangzhou 510301, china south china sea {3. of oceanology Chinese Academy of Sciences Guangzhou 510301 China

The models about lithospheric thickness and thermal conduction inside the lithosphere and the top layer of the asthenosphere have been proposed in this study for four type regions: the midoceanic ridge, the extinct spreading ridge, the lithospheric fault fissure and the mouth of the extinct submarine volcanoes which are in deep sea bottom. The solutions of the models are found to be the same. The formulas of temperature distribution inside the lithosphere and the top layer of the asthenosphere, the lithospheric thicknesses to the heat flow and the crustal ages to the heat flow are obtained. The crustal ages and the lithospheric thicknesses of the central basin are calculated. And they are used to draw the lithospheric thicknesses and crustal ages maps of the central basin (in this paper both the central basin and the basin are the central basin of the south china sea). According to their characteristics, the central basin is divided into three regions. The lithospheric thicknesses, crustal ages and heat flow distribution characteristics are discussed respectively. The formation and evolution of the south china sea are analysed and it is thought that the south china sea has undergone three episode-seafloor spreadings.

关键词： Thermal conduction equation lithospheric thickness crustal age evolution

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Distribution and identification of the low-velocity layer in the northern south china sea

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Progress in Natural Science:Materials International 2007年第5期17卷 591-600页

作者： Zhao Minghui, Qiu Xuelin, Xu Huilong, Shi Xiaobin, Wu Shimin , Ye Chunming and Xia Shaohong (key laboratory of marginal {3. geology, south china {3. institute of oceanology, chinese academy of sciences, guangzhou 510301, china Earthquake Administration of Guangdong Province, {13. 510070, china) key laboratory of marginal {3. geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China Earthquake Administration of Guangdong Province Guangzhou 510070 China

The low-velocity layer (LVL), closely related with tectonic activities and dynamic settings, has always been a hot topic in the deep crustal structure studies. The deep seismic (OBS/OBH) and onshore-offshore experiments have been extensively implemented in the northern south china sea (SCS) since the 1990s. Six seismic profiles were finished on the northern margin of SCS by domestic and international cooperations. The features of crustal structures were revealed and five velocity-inversion layers were discovered. Among them three LVLs with 3.0—3. 5 km·s-1 velocity are located in the sedimentary structure (2.0—6.0 km in depth and 2.0—4. 6 km in thickness) of the Yinggehai Basin and Pearl River Mouth Basin. They were identified by the reflective and refractive phases for their shallow depth. The other two LVLs with 5.5—6.0 km·s-1 velocity generally existed in the middle crust (7.0—18.0 km in depth) with an about 2.5—6.0 km thickness in the transitional crustal structure of the northeastern and northwestern SCS. They were detected by the refractive phase from their overlain and underlying layers. We explored the possible tectonic formation mechanisms combining with previously reported results, which provided evidence for the formation and evolution of SCS.

关键词： low-velocity layer deep crustal structure the northern south china sea OBS/OBH and onshore-offshore seismic experiments.

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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 Ming3.. south china sea {3. of oceanology, chinese academy of sciences. guangzhou 510301, china 2. State key laboratory of Loess and Quaternary geology, Earth Environmental {3., chinese academy of sciences, Xi’an 710075, china 3. {3. of geology and Geophysics, chinese academy of sciences, Beijing 100029, china south china sea {3. of oceanology Chinese Academy of Sciences Guangzhou China State key laboratory of Loess and Quaternary geology 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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