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SEDIMENTARY PROPERTIES AND ENVIRONMENTAL VARIATIONS FROM CONTINENTAL SLOPE TO DEEP SEA PLAIN IN THE NORTHERN SOUTH CHINA SEA SINCE LATE PLEISTOCENE

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Science China Chemistry 1989年第7期32卷 873-883页

作者：冯文科杨达源黎维锋 marine geological investigation brigade Ministry of Geology and Mineral Resources Guangzhou Department of Geography Nanjing University.

The South China Sea is the westernmost marginal sea in the west Pacific Ocean. On thebasis of the analyses of sedimentary components, biofossils, oxygen-carbon isotopes and theirdatings in four seafloor cores which were collected from the deep sea plain to continentalslope in the northern South China Sea, the environmental variations were basically similarto other tropical ocean areas, and their cycle changes in about the ages of 40 ka and 20 kawere more apparent since the late Pleistocene. During the warm climates, the depositionrate on the continental slope was about 2.6 times as rapid as on the deep sea plain *** seafloor in the deep sea plain was below the CaCO_3 compensation depth. During thecold periods, however, the deposition rate on the deep sea plain margin was slightly quickerthan on the continental slope due to the sea level reduction on a larger scale and moresupply of the terrigenous clastics.

关键词： deep sea sediment natural environment palaeoclimate

Sedimentary Features of Shallow Ancient River Channels on the Northern Shelf of the South China Sea

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Acta Geologica Sinica(English Edition) 1995年第1期69卷 85-98页

作者： Kou Yangqi and Du Deli 2nd marine geological investigation Party, MGMR, Guangzhou, Guangdong Jiang M inxi 2nd marine geological investigation Party MGMR Guangzhou Guangdong

Quaternary buried ancient river channels are widespread in the shallow-level sediments of the northern shelf of the South China Sea. The sedimentary sequence mainly of fluvial deposits comprise an important component part of the low-stand system tract and transgressive system tract in the study region. The plannar variation and spatial association of the sedimentary features such as incised valley fillings, deltaic foreset wedges and block slides of shelf-marginal fans reflect the palaeogeographic environment during the fall of the regional sea level in the northern part of the South China Sea. Based on the high-resolution seismic reflection data and gelogical data from boreholes, the present paper makes an integrated interpretation of the Quaternary ancient river channels in the shallow sediments of the study area, studies the sedimentary features of the ancient channels such as their spatial distribution, seismic facies reflection indicators, sedimentary facies and sand -body types, and discusses their formational setting and evolutionary model, with the main purpose to render a service to the hydrocarbon resources exploration and development and marine engineering in the northern shelf of the South China Sea.

关键词： Northern part of the South China Sea continental shelf shallow-buried ancient channels low-stand system tract sea level change

Trace element composition of peridotites from the southern Mariana forearc:Insights into the geochemical effects of serpentinization and/or seafloor weathering

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Chinese Journal of Oceanology and Limnology 2009年第4期27卷 985-992页

作者：汪小妹曾志刚刘长华陈俊兵殷学博王晓媛陈代庚张国良李康陈帅欧阳荷根 Key Laboratory of marine Geology and Environment Institute of OceanologyChinese Academy of Sciences Graduate School of Chinese Academy of Sciences geological brigade of Hydrogeology and Engineering Geology Zhejiang Geological Prospecting Bureau

Peridotites from the southern Mariana forearc were sampled on the landward trench slope of the Izu-Bonin-Mariana (IBM) subduction zone by *** mantle wedge peridotites underwent hydration by fluid derived from a dehydrated descending slab,and later interacted with seawater after emplacement at or near the *** study investigates how these two different rock-fluid interaction processes influenced trace element distribution in the southern Mariana forearc *** measured trace element concentrations of peridotites from the southern Mariana *** southern Mariana forearc peridotites are characterized by a distinct seawater-like REE pattern with an obvious negative Ce anomaly,and La shows good correlation with other REEs (except Ce).In addition,there is a great enrichment of U,Pb,Sr and Li elements,which show a distinct positive anomaly relative to adjacent elements in the multi-element *** the seawater-like REE pattern,we infer that REEs are mainly influenced by seawater during peridotite-seawater interactions after their emplacement at or near the seafloor,by serpentinization or by marine ***,the anomalous behavior of Ce,compared with other rare earth elements in these samples,may indicate that they have undergone reactions involving Ce (IV) when the peridotites interacted with *** U,Pb,Sr and Li anomalies are inferred to be related to seawater and/or fluids released during dehydration of the subducting slab.

关键词： peridotites forearc Mariana element negative Ce anomaly

Talc-bearing serpentinized peridotites from the southern Mariana forearc:implications for aseismic character within subduction zones

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Chinese Journal of Oceanology and Limnology 2009年第3期27卷 667-673页

作者：汪小妹曾志刚刘长华陈俊兵殷学博王晓媛陈代庚张国良陈帅李康欧阳荷根 Key Laboratory of marine Geology and Environment Institute of OceanologyChinese Academy of Sciences Graduate School of Chinese Academy of Sciences geological brigade of Hydrogeology and Engineering Geology Zhejiang Geological Prospecting Bureau

The serpentinized peridotites overlying the subducted zones in the Izu-Bonin-Mariana(IBM) arc system have been interpret as the cause of the low-velocity layer identified beneath the IBM froearc,in turn few earthquakes occurred along the plate ***,which is a low temperature and highly hydrated phase of serpentine with low frictional strength,has been suggested as the low velocity material in the serpentinized peridotites,besides,brucite is inferred to be likely conducive to stable ***,such idea encounters challenging in our serpentinized peridotites from the southern Mariana forearc,which absent both the above *** presence of talc,which characterized by its weak,low-friction and inherently stable sliding behavior,provides new *** we report the occurrence of talc in serpentinized peridotites collected from the landward trench slope of the southern Mariana *** infer that talc is mainly forming as a result of the reaction of serpentine minerals with silica-saturated fluids released from the subducting slab,and talc also occurs as talc veins *** to its unique physical properties,talc may therefore play a significant role in aseismic slip in the IBM subduction zone.

关键词： talc serpentinized peridotites Mariana aseismic subducfion zone

Structural Origin of the Red-Ribbon Style Iron Ores in the Xinyu Iron Deposit,Central Jiangxi Province

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Acta Geologica Sinica(English Edition) 2015年第2期89卷 691-692页

作者： CHEN Zhengle ZHANG Qing CHEN Bailin WANG Xueping SHEN Tao WU Junjie Institute of Geomechanics Chinese Academy of Geological Sciences East China Institute of Technology geological investigation Team in Western Jiangxi Province

The Xinyu iron deposit, located in central Jiangxi Province, is one of the most important BIF-type deposits in China. It is hosted in the Late Proterozoic volcanic- sedimentary rocks, which are composed of sericite- chlorite pyhllite, magnetite-bearing chlorite phyllite or schist, magnetite quartzite, and schist （Yu et al., 1989; Zeng et al., 2011）.

关键词： Structural Origin of the Red-Ribbon Style Iron Ores in the Xinyu Iron Deposit Central Jiangxi Province

Astronomical Cycles of the Late Permian Lopingian in South China and Their Implications for Third-Order Sea-Level Change

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Journal of Ocean University of China 2020年第6期19卷 1331-1344页

作者： WANG Xiuqi ZHANG Xunhua GAO Fei ZHANG Minghua College of marine Geosciences Ocean University of ChinaQingdao 266100China Qingdao Institute of marine Geology China Geological SurveyQingdao 266071China Qingdao Jimo Municipal Transport Bureau Qingdao 266200China The brigade of geological Survey of Ganxi Bureau of Geologic Exploration and Mineral Development of Jiangxi ProvinceNanchang 330002China

The late Permian(Lopingian)was a crucial climate transition period from the late Paleozoic Ice Age to the early Triassic of exceptionally high ***,the origins of the third-order sea-level changes during the Lopingian Epoch remain ***,we presented astronomically calibrated gamma-ray(GR)log and non-U GR(computed gamma ray or CGR)curves from the clastic and carbonate successions of well GFD-1 in the Pingle Depression of South China for studying the sea-level oscillations during the *** analyses of the 405 kyr-calibrated GR and CGR time data revealed periodicities close to about 405,about 100,about 44.2,about 35.1,about 21,and about 17.5 kyr,supporting the existence of Milankovitch forcing in the sedimentary records.A high-resolution astronomical time scale and high-resolution sedimentation rate curve of the Lopingian from well GFD-1 were constructed by cyclostratigraphic *** eccentricity and obliquity amplitude modulation cycles suggested long periodicities of about 2.4 and about 1.2 myr,*** the Wuchiapingian greenhouse of the Lopingian,the about 2.4 myr eccentricity oscillation controlled‘weak’glacio-eustasy and/or aquifer eustatic changes related to the global third-order sea-level changes and that a lowstand(W2)was initiated by an eccentricity oscillation *** contrast,during the Changhsingian,which exhibited a cooling event,an about 1.2 myr obliquity cycle was probably strong,with the sea-level records highlighting the link between the‘icehouse’sea-level lowering(C2 and C1)and the obliquity ***,dynamic sedimentary noise model as an indicator of sea-level showed local third-order sea-level variations,the coevolution trends in the orbital power,global and local sea-level changes,and sedimentation rate had significant implications for establishing the global nature and synchronicity of these million-year-scale eustatic records and reconstructing the temporal depositional history at a region

关键词： Lopingian Milankovitch cycle third-order eustasy long-period astronomical cycle sedimentation rate

Potential morphological responses of an artificial beach to a flood in extreme events: field observation and numerical modelling

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Acta Oceanologica Sinica 2024年第7期43卷 78-92页

作者： Jiadong Fan Cuiping Kuang Xuejian Han Lixin Gong Huixin Liu Jiabo Zhang College of Civil Engineering Tongji UniversityShanghai 200082China The Eighth geological brigade Hebei Geological and Mineral Exploration Development BureauQinhuangdao 066001China marine Ecological Restoration and Smart Ocean Engineering Research Center of Hebei Province Qinhuangdao 066001China

Conch Island is a typical artificial island at the Tanghe Estuary in Bohai Sea,*** improve natural environment and boost local tourism,beach nourishment will be applied to its north-western *** projected beach is landward and opposite to the Jinmeng Bay ***,with climate changes,frequent heavy rainfalls in Hebei Province rise flood hazards at the Tanghe *** this circumstance,potential influences on the projected beach of a flood are investigated for sustainable managements.A multi-coupled model is established and based on the data from field observations,where wave model,flow model and multifraction sediment transport model are *** addition,the impacts on the projected beach of different components in extreme events are discussed,including the spring tides,storm winds,storm waves,and sediment *** numerical results indicate the following result.(1)Artificial islands protect the coasts from erosion by obstructing landward waves,but rise the deposition risks along the target shore.(2)Flood brings massive sediment inputs and leads to scours at the estuary,but the currents with high sediment concentration contribute to the accretions along the target shore.(3)The projected beach mitigates flood actions and reduces the maximum mean sediment concentration along the target shore by 20%.(4)The storm winds restrict the flood and decrease the maximum mean sediment concentration by 21%.With the combined actions of storm winds and waves,the maximum value further declines by 38%.(5)A quadratic polynomial relationship between the deposition depths and the maximum sediment inputs with flood is established for estimations on the potential morphological changes after the flood process in extreme *** the uncertainty of estuarine floods,continuous monitoring on local hydrodynamic variations and sediment characteristics at Tanghe Estuary is necessary.

关键词： beach nourishment flood artificial island sediment transport extreme events storm

Light carbon isotope events of foraminifera attributed to methane release from gas hydrates on the continental slope, northeastern South China Sea

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Science China Earth Sciences 2016年第10期59卷 1981-1995页

作者： ZHUANG Chang CHEN Fang CHENG SiHai LU HongFeng WU Cong CAO Jun DUAN Xiao Key Laboratory of marine Mineral Resources Ministry of Land and ResourceGuangzhou Marine Geological Survey

In 2013, the China geological Survey and Guangzhou marine geological Survey conducted the second Chinese gas hydrate expedition in the northern South China Sea （SCS） and successfully obtained visible gas hydrate samples. Five of the thirteen drilling sites were cored for further research. In this work, Site GMGS2-08 is selected for the stable isotopic analy- sis of foraminifera present in the boreholes in order to reveal the carbon isotopic characteristics of the foraminifera and their response to methane release in the gas hydrate geological system. Our results show that the methane content at Site GMGS2-08 is extremely high, with headspace methane concentrations up to 39300 μmol L^-1. The hydrocarbon δ^13C values, ranging from -69.4%o to -72.3‰ PDB, distinctly indicate biogenic generation. Based on the δD analytical results （-183‰ to -185‰ SMOW）, headspace methane is further discriminated to be microbial gas, derived from CO2 reduction. By isotopic measurement, five light δ^13C events are found in the boreholes from Site GMGS2-08, with foraminiferal δ^13C values being ap- parently lower than the normal variation range found in the glacial-interglacial cycles of the SCS. The δ^13C values of benthic Uvigerina peregrina are extremely depleted （as low as -15.85‰ PDB）, while those of planktonic Globigerinoides ruber reach -5.68‰ PDB. Scanning electron micrograph （SEM） studies show that foraminiferal tests have experienced post-depositional alteration, infilled with authigenic carbonate, and the diagenetic mineralization is unlikely to be related to the burial depths. The correlation calculation suggests that the anaerobic oxidation of organic matter has only weak influences on the δ^13C com- position of benthic foraminifera. This means that the anomalous δ^13C depletions are predominantly attributed to the overprint- ing of secondary carbonates derived from the anaerobic oxidation of methane （AOM）. Furthermore, the negative δ^13C anoma- lies, coupled with the positive

关键词： Gas hydrates Carbon isotopes Foraminifera South China Sea Taixinan Basin

Numerical study on the deformation of soil stratum and vertical wells with gas hydrate dissociation

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Acta Mechanica Sinica 2016年第5期32卷 905-914页

作者： Xudong Chen Xuhui Zhang Xiaobing Lu Wei Wei Yaohong Shi Institute of Mechanics Chinese Academy of Sciences Research Institute of Petroleum Exploration and Development-Langfang marine Environmental and Engineering geological Survey Guangzhou Marine Geological Survey

Gas hydrate（GH） dissociates owing to thermal injection or pressure reduction from the well in gas/oil or GH exploitation. GH dissociation leads to, for example, decreases in soil strength, engineering failures such as wellbore instabilities, and marine landslides. The FLAC3 D software was used to analyze the deformation of the soil stratum and vertical wells with GH dissociation. The effects of Young＇s modulus, internal friction angle, cohesion of the GH layer after dissociation, and the thickness of the GH layer on the deformation of soils were studied. It is shown that the maximum displacement in the whole soil stratum occurs at the interface between the GH layer and the overlayer. The deformation of the soil stratum and wells increases with decreases in the modulus, internal friction angle, and cohesion after GH dissociation. The increase in thickness of the GH layer enlarges the deformation of the soil stratum and wells with GH dissociation. The hydrostatic pressure increases the settlement of the soil stratum, while constraining horizontal displacement. The interaction between two wells becomes significant when the affected zone around each well exceeds half the length of the GH dissociation zone.

关键词： Gas hydrate Dissociation FLAC3D Soil stratum Well