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Acta Geologica Sinica(English Edition) 2013年第3期87卷 804-818页

作者： YU Xinghe WANG Jianzhong LI Shengli FANG Jingnan JIANG Longyan CONG Xiaorong LIANG Jinqiang SHA Zhibin China University of Geosciences guangzhou marine geological survey

BSR （Bottom Simulating Reflector） occurs widely in the strata since the late Miocene in the deep-water area of the northern continental slope of South China Sea （SCS）. It is an important seismic reference mark which identifies the gas hydrate and its distribution influenced by the tectonic movements. Single-point basin modeling was conducted using 473 points in the study area. To discuss the relationships between the tectonic subsidence and BSR, the volume and rate of tectonic subsidence in each geological time have been simulated. The results show that there are three tectonic accelerate subsidence processes in the study area since the late Miocene, especially since 1.8Ma the tectonic subsidence accelerates more apparently. Since the Late Miocene to Pleistocene, the rate of tectonic subsidence in deep-water underwent a transformation from weak to strong. The ratio of tectonic subsidence to the total subsidence was relatively high （65-70%）. Through the superposition of the BSR developed areas and the contours of tectonic subsidence in this area, it was discovered that more than 80% of BSR tend to be distributed at the slope break or depression-uplift structural transfer zone and the average tectonic subsidence rate ranges from 70 m/Ma to 125 m/Ma.

关键词： BSR tectonic subsidence quantitative simulation deep-water area Northern continental slope of South China Sea

Acoustic characteristics of cold-seep methane bubble behavior in the water column and its potential environmental impact

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Acta Oceanologica Sinica 2020年第5期39卷 133-144页

作者： Jiangong Wei Tingting Wu Xiguang Deng Zongze Yu Lifeng Wang Gas Hydrate Engineering and Technology Center Guangzhou Marine Geological SurveyGuangzhou 510075China MLR Key Laboratory of marine Mineral Resources Guangzhou Marine Geological SurveyGuangzhou 510075China

The amount of methane leaked from deep sea cold seeps is enormous and potentially affects the global warming,ocean acidification and global carbon *** is of great significance to study the methane bubble movement and dissolution process in the water column and its output to the *** bubbles produce strong acoustic impedance in water bodies,and bubble strings released from deep sea cold seeps are called"gas flares"which expressed as flame-like strong backscatter in the water *** characterized the morphology and movement of methane bubbles released into the water using multibeam water column data at two cold *** result shows that methane at site I reached 920 m water depth without passing through the top of the gas hydrate stability zone(GHSZ,850 m),while methane bubbles at site II passed through the top of the GHSZ(597 m)and entered the non-GHSZ(above 550 m).By applying two methods on the multibeam data,the bubble rising velocity in the water column at sites I and II were estimated to be 9.6 cm/s and 24 cm/s,*** velocity is positively associated with water depth which is inferred to be resulted from decrease of bubble size during methane ascending in the *** with numerical simulation,we concluded that formation of gas hydrate shells plays an important role in helping methane bubbles entering the upper water bodies,while other factors,including water depth,bubble velocity,initial kinetic energy and bubble size,also influence the bubble residence time in the water and the possibility of methane entering the *** estimate that methane gas flux at these two sites is 0.4×10~6–87.6×10~6 mol/a which is extremely small compared to the total amount of methane in the ocean body,however,methane leakage might exert significant impact on the ocean acidification considering the widespread distributed cold *** addition,although methane entering the atmosphere is not observed,further research is still needed to

关键词： gas bubble methane cold seep Nigerian Continental Margin Greenhouse effect Makran accretion wedge

Late Quaternary Calcareous Nannofossils from the Offshore Sediments in southern Hongkong

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Acta Geologica Sinica(English Edition) 1999年第2期73卷 242-247页

作者： HUANG Yongyang CHEN Fang guangzhou marine geological survey MGMR Guangzhou 510075

Abstract Based upon the features of nannofossil composition, distribution, abundance and diversity, the fossil-bearing sediments exposed by five drill holes in the offshore area of southern Hongkong can be divided into the upper Middle Pleistocene, the Upper Pleistocene and Holocene. There were two palaeoclimatic stages in the Holocene in this area according to fossil palaeoecologic and sedimentation analyses: the temperature-rising stage and the warm stage. The latter involves two temperature-falling periods, which could be the major factor causing sea-level fall during that time.

关键词： nannofossil Quaternary palacooceanography Lingdingyang southern Hongkong

Tertiary Calcareous Nannofossil Biostratigraphy in the North Part of the South China Sea

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Acta Geologica Sinica(English Edition) 1991年第3期65卷 321-338,343-344页

作者： Duan Weiwu and Huang Yongyang Gangzhou marine geological survey, Ministry of Geology and Mineral Resources, guangzhou Chang Zhijun and Sun Sheping guangzhou marine geological survey Ministry of Geology and Mineral Resources Guangzhou

The marine Tertiary sequence in the north part of the South China Sea may be divided into 18 LateOligocene to Pliocene calcareous nannofossil zones and one unnamed Eocene assemblage based on an analysisof calcareous nannofossils from 40 offshore boreholes. The unnamed Eocene assemblage has been found onlyon the northeast margin of the Zhujiangkou basin. The 18 cakareous nannofossil zones of the Late Oligoceneto Pliocene were deposited in succession, but their development degrees are different. Among the 18 calcareousnannofossil zones, those corresponding to Martini's (1971) NN4- NN5 zones, NN11 zone and NN13-NN15zones are well developed, relatively persistent laterally and also widely distributed. They are the importantmarkers for the stratigraphical subdivision and correlation of the Upper Tertiary between the various basins inthe north part of the South China Sea. Based on the calcareous nannofossils and the sedimentsry features coup-led with the foraminifer zonation in certain basins, the present paper discusses the sedimentary characteristicsof the marine Tertiary and as well as the distribution and development of the sedimentary hiatus in the *** calcareous nannofossil markers for the Upper / Lower Tertiary and the Quaternary / Tertiary boundaries,and the characteristics and geological significance of the reworked calcareous nannofossils are also discussed inthe paper.

关键词： Tertiary Calcareous Nannofossil Biostratigraphy in the North Part of the South China Sea

Gas Sources of Natural Gas Hydrates in the Shenhu Drilling Area, South China Sea: Geochemical Evidence and geological Analysis

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Acta Geologica Sinica(English Edition) 2013年第3期87卷 767-776页

作者： ZHU Youhai HUANG Xia FU Shaoying SU Pibo Oil & Gas survey China Geological Survey Institute of Mineral Resources Chinese Academy of Geological Sciences guangzhou marine geological survey

The Shenhu gas hydrate drilling area is located in the central Baiyun sag, Zhu I! depression, Pearl River Mouth basin, northern South China Sea. The gas compositions contained in the hydrate-bearing zones is dominated by methane with content up to 99.89% and 99.91%. The carbon isotope of the methane （δ^13C1） are -56.7%0. and -60.9%0, and its hydrogen isotope （δD） are -199%0 and -180%0, respectively, indicating the methane from the microbial reduction of CO2. Based on the data of measured seafloor temperature and geothermal gradient, the gas formed hydrate reservoirs are from depths 24-1699 m below the seafloor, and main gas-generation zone is present at the depth interval of 416-1165 m. Gas-bearing zones include the Hanjiang Formation, Yuehai Formation, Wanshan Formation and Quaternary sediments. We infer that the microbial gas migrated laterally or vertically along faults （especially interlayer faults）, slump structures, small-scale diapiric structures, regional sand beds and sedimentary boundaries to the hydrate stability zone, and formed natural gas hydrates in the upper Yuehai Formation and lower Wanshan Formation, probably with contribution of a little thermogenic gas from the deep sedments during this process.

关键词： natural gas hydrate methane microbial gas gas source migration South China Sea

Patterns of gas hydrate accumulation in mass transport deposits related to canyon activity: Example from Shenhu drilling area in the South China Sea

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Acta Oceanologica Sinica 2019年第5期38卷 118-128页

作者： Chao Fu Shengli Li Xinghe Yu Jinqiang Liang Zenggui Kuang Yulin He Lina Jin School of Energy Resources China University of Geosciences guangzhou marine geological survey China Geological Survey

Since 2017, a plenty of gas hydrates have been drilled in a new area of Shenhu, and good heterogeneity has been found throughout the spatial distribution of the reservoir. After distinguishing different sedimentary sequence types and matching their formation with slope deposition settings, this study proposes three mass transport deposit(MTD) patterns related to canyon activity that occurred contemporaneously or epigenetically with it: well preserved MTDs, MTDs eroded by canyon migration, and MTDs dislocated by contemporaneous faults. Based on seismic reflection characteristics, this study proposed methods of quantitatively analyzing sedimentary factors,such as measuring the turbidities flow rate in the canyon, and results are interpreted with respect to canyon activity. Combining the above parameters and their relationship with gas hydrate accumulation, fine-grained seals overlapping coarse MTDs reservoirs are found to be indispensable to gas hydrate accumulation, as they prevent the release of free gas. Based on grain size data of hydrate samples from drilling wells, multi-layered gas hydrate reservoirs capped by fine-grained sediments and overlapping mud show favorable hydrate-bearing prospects. The release of gas hydrates, however, is mostly caused by the lack of mud sealing in relation to canyon activity, such as turbidities flow erosion and contemporaneous fault breaking. Canyon migration with respect to MTDs may be the actual cause of erosion of overlapping syn-sedimentary layers, and high bottom flows may contribute to an increase in the release of free gas. It is believed that contemporaneous faults caused by unstable canyon walls may break the muddy over layers and decrease the accumulation pressure of gas hydrate ***, according to the sedimentary characteristics of MTDs and the hydrate accumulation process, three responding accumulation or releasing patterns are proposed, which respond to the different types of MTDs distinguished above: a well-pr

关键词： South China Sea gas hydrate sedimentary characteristics MTDs hydrate responding pattern

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

Bacterial diversity in sediments of core MD05-2902 from the Xisha Trough,the South China Sea

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Acta Oceanologica Sinica 2014年第10期33卷 85-93页

作者： LI Tao WANG Peng State Key Laboratory of marine Geology Tongji University guangzhou marine geological survey

A sediment core MD05-2902 was collected from the deep-sea basin of the Xisha Trough. The vertical distribution and diversity of bacteria in the core was investigated through ten sub-sampling with an interval of 1 m using bacterial 16 S rRNA gene as a phylogenetic bio-marker. Eighteen phylogenetic groups were identified from 16 S rRNA gene clone libraries. The dominant bacterial groups were JS1, Planctomycetes and Chloroflexi, which accounted for 30.6%, 16.6%, and 15.6% of bacterial clones in the libraries, respectively. In order to reveal the relationship between biotic and abiotic data, a nonmetric multidimensional scaling analysis was performed. The result revealed that the δ15N, δ13C, total organic carbon and total organic nitrogen possibly influenced the bacterial community structure. This study expanded our knowledge of the biogeochemical cycling in the Xisha Trough sediment.

关键词： Xisha Trough bacterial diversity 16S rRNA gene

Zircon U-Pb Ages of the Granodioritic Porphyry in the Laba Molybdenum Deposit,Yunnan,SW China and Its geological Implication

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Acta Geologica Sinica(English Edition) 2014年第4期88卷 1183-1194页

作者： YU Haijun LI Wenchang YIN Guanghou LU Yingxiang CAO Xiaomin HUANG Dingzhu DONG Tao ZHANG Youming Yunnan geological survey bureau

The Geza island-arc is a well-known mineralization concentration area, part of the Sanjiang Domain at the east margin of the Tibetan Plateau. In recent years, several Late Yanshanian granitic intrusions and associated deposits have been found in this region, the largest one of which in the Shangri-La region is the Laba molybdenum deposit. Previous studies suggested that the timing of the Laba mineralization is 85 ±2 Ma. However, the ages of the granodioritic porphyry remain unknown. In this study, LA-ICP-MS U-Pb dating of zircons from three samples of the molybdenite-bearing granodioritic porphyry has been conducted with resulting dates of 85.00±0.23 Ma （MSWD = 0.58）, 85.28 ± 0.28 Ma （MSWD = 1.12）, and 84.83 ± 0.26 Ma （MSWD = 0.79）, respectively, indicating that these granodioritie porphyries formed in the Late Yanshanian around -85 Ma. Combined with the geological features of the mineralization, the Laba deposit is spatially, temporally, and probably genetically associated with the granodioritic porphyries. In addition, the ages of the Laba deposits are consistent with the other Late Yanshanian intrusions and mineralization, suggesting that the mineralization was probably generated under an intra-plate extensional environment during the Late Cretaceous.

关键词： geochronology mineralogy U-Pb dating of zircons Geza island-arc Cretaceous,molybdenum Yunnan province Tibetan plateau