Geochemical Characteristics of Sediments at Site HQ-48PC in Qiongdongnan Area, the North of the South China Sea, and Their Implication for Gas Hydrates

Abstract

Abstract:

The Qiongdongnan area is one of the most prospective areas of the gas hydrate exploration in the northern continental slope of the South China Sea. Headspace gas and pore water samples were collected from sediment core in Site HQ-48PC in this area. Comprehensive studies on methane concentrations in headspace gas, anions, cations and trace element contents in pore water indicate that strong anaerobic methane oxidation(AMO) occurres at the sulfatemethane interface(SMI), with the calculated depth of 605 mbsf by Linear Regression. For example, the concentration of dissolved sulfate(SO2-4) decreases linearly to zero, while that of methane increases abruptly; the concentrations of pyrite and organic carbon in sediments reach maximum value, and that of dissolved Ba2+ behaves as a Ba front character. The concentrations of alkalinity(HCO^-3) increase clearly with the increasing of the depth above the SMI; those of Ca ²⁺ ,Mg²⁺,Sr²⁺show a decreasing trend, and the ratio of Mg²⁺/Ca²⁺increases sharply. The main product of authigenic carbonates is calcite above the SMI. The concentration of HCO^-3 decreases slowly with the increasing of depth below the SMI; and concentration of Mg²⁺,Sr²⁺show the same trend with the increasing of depth above the SMI, but the concentration of Ca²⁺ shows little fluctuation, which results in a decreasing ratio of Mg²⁺/Ca²⁺. The main product of authigenic carbonates is dolomite in this region. The concentrations of phosphate(PO3-4) and ammonium(NH+4) in pore water of sediment core in Site HQ-48PC are high and increase clearly with depth;the increasing trend has an enantiomorphous relation to the decreasing trend of the concentration of SO₂^-4. These geochemical characteristics are similar to those of the shallow sediments where the gas hydrate occurs in the world, strongly indicating that there should be gas hydrate reservoirs underneath.

Key words: northern continental slope of the South China Sea, Qiongdongnan area, gas hydrate, geochemistry, Anaerobic Methane Oxidation(AMO), SulfateMethane Interface(SMI)

CLC Number:

P736.21

WU Lu-Shan, YANG Sheng-Xiong, LIANG Jin-Qiang, SU Xin, YANG Tao. Geochemical Characteristics of Sediments at Site HQ-48PC in Qiongdongnan Area, the North of the South China Sea, and Their Implication for Gas Hydrates[J]. Geoscience, 2010, 24(3): 534-544.

References

［1］Kvenvolden K A, Ginsburg G D, Soloviev V A. Worldwide distribution of subaquatic gas hydrates
[J]. GeoMarine Letters, 1993, 13: 32-40.
［2］Kvenvolden K A. A primer on the geological occurrence of gas hydrate
[M]// Henriet J P, Mienert J. Gas Hydrates: Relevance to World Margin Stability and Climate Change. London: Geological Society Special Publications, 1998: 9-30.
［3］Borowski W S, Paull C K, Ussler W III. Global and local variations of interstitial sulfate gradients in deepwater, continental margin sediments: Sensitivity to underlying methane and gas hydrates
[J]. Marine Geology, 1999, 159:131-154.
［4］Pall C K, Matsumoto R. Leg 164 Overview
[M]// Paull, C K, Matsumoto R, Wallace P J, et al. Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 164. College Station. Texas: Texas A & M University (Ocean Drilling Program ), 2000: 3-12.
［5］牛滨华，孙春岩，苏新，等.勘查地球化学方法适用于勘查天然气水合物的依据
[J].现代地质，2005，19(1): 61-66.
［6］Milkov A V, Claypool G E, Lee Y J. In situ methane concentrations at Hydrate Ridge, offshore Oregon:new constraints on the global gas hydrate inventory from an active margin
[J]. Geology, 2003, 31(10):833-836.
［7］Borowski W S. A review of methane and gas hydrates in the dynamic, stratified system of the Blake Ridge region, offshore southeastern North America
[J]. Chemical Geology, 2004, 205:311-346.
［8］Kvenvolden K A. A review of the geochemistry of methane in natural gas hydrate
[J]. Organic Geochemistry, 1995, 23(11/12): 997-1008.
［9］Hesse R. Pore water anomalies of submarine gashydrate zones as tool to assess hydrate abundance and distribution in the subsurface: What have we learned in the past decade?
[J]. EarthScience Reviews, 2003, 61:149-179.
［10］Hesse R, Frape S K, Egeberg P K, et al. Stable isotope studies (Cl, O, and H) of interstitial waters from Site 997, Blake Ridge gas hydrate field, West Atlantic
[M]// Paull C K, Matsumoto R, Wallace P J, et al. Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 164. College Station. Texas: Texas A & M University (Ocean Drilling Program ), 2000: 129-137.
［11］Tomaru H, Matsumoto R, Torres M E, et al. Geological and geochemical constraints on the isotopic composition of interstitial waters from the Hydrate Ridge region, Cascadia continental margin
[M]// Tréhu A M, Bohrmann G, Torres M E, et al. Proceedings of the Ocean Drilling Program, Scientific Results Vol. 204. College Station, Texas: Texas A & M University (Ocean Drilling Program ), 2006: 1-20.
［12］Malinverno A, Kastner M, Torres M E, et al. Gas hydrate occurrence from pore water chlorinity and downhole logs in a transect across the northern Cascadia margin (Integrated Ocean Drilling Program Expedition 311)
[J]. Journal of Geophysical Research, 2008, 113: B08103.
［13］Borowski W S, Paull C K, Ussler W III. Carbon cycling within the upper methanogenic zone of continental rise sediments: An example from the methanerich sediments overlying the Blake Ridge gas hydrate deposits
[J]. Marine Chemistry, 1997, 57: 299-311.
［14］Borowski W S, Hoehler T M, Alperin M J, et al. Significance of anaerobic methane oxidation in methanerich sediments overlying the Blake Ridge gas hydrates
[M]// Paull C K, Matsumoto R, Wallace P J, et al. Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 164. College Station, Texas: Texas A & M University (Ocean Drilling Program ), 2000: 87-99.
［15］Borowski W S. Data report: Dissolved sulfide concentration and sulfur isotopic composition of sulfide and sulfate in pore waters, ODP Leg 204, Hydrate Ridge and vicinity, Cascadia Margin, offshore Oregon
[M]// Tréhu A M, Bohrmann G, Torres M E, et al. Proceedings of the Ocean Drilling Program, Scientific Results Vol. 204. College Station, Texas: Texas A & M University (Ocean Drilling Program ), 2006: 1-13.
［16］黄永样，张光学.我国海域天然气水合物地质-地球物理特征及前景
[M].北京：地质出版社，2009: 1-243.
［17］Zhang H, Yang S, Wu N, et al. Successful and surprising results for Chinas first gas hydrate drilling expedition
[ R ]. Fire in the Ice:Methane Hydrate Newsletter, National Energy Technology Laboratory, U.S. Department of Energy, 2007: 6-9.
［18］Reed D L, Lundberg N, Liu C S, et al. Structural relations along the margin of the offshore Taiwan accretionary: implications for accretion and crustal kinematics
[J]. Acta Geologica Taiwanica, 1992, 30: 105-122.
［19］姚伯初.南海北部陆缘天然气水合物初探
[J].海洋地质与第四纪地质，1998，18(4): 11-18.
［20］祝有海，张光学，卢振权，等.南海天然气水合物成矿条件与找矿前景
[J].石油学报，2001，22(5): 6-12.
［21］王宏语，孙春岩，黄永样，等.海上气态烃快速测试与西沙海槽天然气水合物资源勘查
[J].现代地质，2002，16 (2): 186-189.
［22］吴必豪，张光学，祝有海，等.中国近海天然气水合物的研究进展
[J].地学前缘，2003，10(1): 177-186.
［23］孙春岩，王宏语，牛滨华.西沙海槽天然气水合物地球化学勘探
[J].地球科学，2004，29(2): 135-140.
［24］祝有海，饶竹，刘坚，等.南海西沙海槽S14 站位的地球化学异常特征及其意义
[J].现代地质，2005，19(1): 39-44.
［25］陆红锋，刘坚，陈芳，等.南海台西南区碳酸盐岩矿物学和稳定同位素组成特征——天然气水合物存在的主要证据之一
[J].地学前缘，2005，12(3): 268-276.
［26］邓希光，付少英，黄永样，等.南海北部东沙群岛HD196站位地球化学特征及其对水合物的指示
[J].现代地质，2006，20(1)：92-102.
［27］苏新，陈芳，陆红锋，等.南海北部深海甲烷冷泉自生碳酸盐岩显微结构特征与流体活动关系初探
[J].现代地质，2008，22(3)：376-381.
［28］王力锋，赵克斌，黄欣.南海北部陆坡热流与天然气水合物赋藏研究
[J].石油实验地质，2009，31(1)：58-62，67.
［29］付少英.东沙群岛海域沉积物游离烃和孔隙水特征及其地球化学意义
[J].南海地质研究，2005(1)：29-37.
［30］蒋少涌，杨涛，薛紫晨，等.南海北部海区海底沉积物中孔隙水的Cl-和SO2-4浓度异常特征及其对天然气水合物的指示意义
[J].现代地质，2005，19(1): 45-54.
［31］杨涛，蒋少涌，葛璐，等. 南海北部陆坡西沙海槽XS-01站位沉积物孔隙水的地球化学特征及其对天然气水合物的指示意义
[J]. 第四纪研究，2006，26(3): 442-448.
［32］Yang T, Jiang S Y, Ge L, et al. Geochemical characteristics of pore water in shallow sediments from Shenhu area of South China Sea and their significance for gas hydrate occurrence
[J]. Chinese Science Bulletin, 2010, 55(8): 752-760.
［33］Yang T, Jiang S Y, Yang J H, et al. Dissolved inorganic carbon (DIC) and its carbon isotopic composition in sediment pore waters from the Shenhu area, northern South China Sea
[J]. Journal Oceanography, 2008, 64: 303-310.
［34］黄永样，Suess E，吴能友，等.南海北部陆坡甲烷天然气水合物地质——中德合作SO-177航次成果专报
[M].北京：地质出版社，2008: 1-197.
［35］王宏斌，张光学，杨木壮，等.南海陆坡天然气水合物成藏的构造环境
[J].海洋地质与第四纪地质，2003，23(1): 81-86.
［36］黄保家.琼东南盆地天然气潜力及有利勘探方向
[J].天然气工业，1999，19(1)：34-40.
［37］陈多福，李绪宣，夏斌.南海琼东南盆地天然气水合物稳定域分布特征及资源预测
[J].地球物理学报，2004，47(3)：483-489.
［38］王秀娟，吴时国，董冬冬，等.琼东南盆地气烟囱构造特点及其与天然气水合物的关系
[J].海洋地质与第四纪地质，2008，28(3): 103-108.
［39］孙春岩，吴能友，牛滨华，等.南海琼东南盆地气态烃地球化学特征及天然气水合物资源远景预测
[J].现代地质，2007，21(1)：95-100.
［40］蒲燕萍，孙春岩，陈世成，等.南海琼东南盆地-西沙海槽天然气水合物地球化学勘探与资源远景评价
[J]，地质通报，2009，28(11)：1656-1661.
［41］邬黛黛，叶瑛，吴能友，等.琼东南盆地与甲烷渗漏有关的早期成岩作用和孔隙水化学组分异常
[J].海洋学报，2009，31(2)：86-96.
［42］程思海，陈道华，张欣，等.海底天然气水合物地球化学探测技术
[J].海洋地质动态，2003，19(10)：30-34.
［43］程思海，陆红锋.海洋沉积物孔隙水的制备方法
[J].岩矿测试，2005，24(2)：102-104.
［44］Westrich J T, Berner R A. The role of sedimentary organic matter in bacterial sulfate reduction: The G model tested
[J]. Limnology and Oceanography, 1984, 29(2): 236-249.
［45］Canfield D E. Sulfate reduction in deepsea sediments
[J]. American Journal of Science, 1991, 291(2): 177-188.
［46］Reeburgh W S. Methane consumption in Cariaco Trench waters and sediments
[J]. Earth and Planetary Science Letters, 1976, 28: 337-344.
［47］Borowski W S, Paull C K, Ussler W III. Marine porewater sulfate profiles indicate in situ methane flux from underlying gas hydrate
[J]. Geology, 1996, 24(7): 655-658.
［48］Dickens G R. Sulfate profiles and barium fronts in sediment on the Blake Ridge: Present and past methane fluxes through a large gas hydrate reservoir
[J]. Geochimica et Cosmochimica Acta, 2001, 65(4): 529-543.
［49］Claypool G E, Kaplan I R. The origin and distribution of methane in sediments
[M]// Kaplan I R. Natural Gases in Marine Sediments. New York: Plenum Press, 1974: 99-139.
［50］杨涛，蒋少涌，葛璐，等.南海北部神狐海域浅表层沉积物中孔隙水的地球化学特征及其对天然气水合物的指示意义
[J].科学通报，2009，54(20)：3231-3240.
［51］Zhang C L, Lanoil B. Geomicrobiology and biogeochemistry of gas hydrates and cold seeps
[J]. Chemical Geology, 2004, 205:187-194.
［52］吴能友，张海啟，杨胜雄，等.南海神狐海域天然气水合物成藏系统初探
[J].天然气工业，2007，27(9)：1-7.
［53］Sassen R, Roberts H H, Carney R , et al. Free hydrocarbon gas, gas hydrate, and authigenic minerals in chemosynthetic communities of the northern Gulf of Mexico continental slope: relation to microbial processes
[J]. Chemical Geology , 2004, 205: 195-217.
［54］刘坚，陆红锋，廖志良，等.东沙海域浅层沉积物硫化物分布特征及其与天然气水合物的关系
[J].地学前缘，2005，12(3)：258-262.
［55］陆红锋，陈芳，廖志良，等.南海东北部HD196A岩心的自生条状黄铁矿
[J].地质学报，2007，81(4)：519-525.
［56］Snyder G T, Dickens G R, Castellini D G. Labile barite contents and dissolved barium concentrations on Blake Ridge: New perspectives on barium cycling above gas hydrate systems
[J]. Journal of Geochemical Exploration, 2007, 95: 48-65.
［57］Kastner M, Elderfield H, Martin J B, et al. Diagenesis and interstitial water chemistry at the Peruvian continental marginmajor constituents and strontium isotopes
[M]// Suess E, Von H R, Emeis K C, et al. Proceedings of the Ocean Drilling Program, Scientific Results Vol.112. College Station, Texas: Texas A & M University (Ocean Drilling Program ), 1990: 413-440.
［58］Curtis C D, Coleman M L. Controls on the precipitation of early diagenetic calcite, dolomite, and siderite concretions in complex depositional sequences
[M]// Gautier D L. Roles of Organic Matter in Sediment Diagenesis. Tulsa: Society of Economic Paleontologists and Mineralogists, 1986, 38:23-33.
［59］Rodriguez N M, Paull C K, Borowski W S. Zonation of authigenic carbonates within gas hydratebearing sedimentary sections on the Blake Ridge: Offshore southeastern north America
[M]// Paull C K, Matsumoto R, Wallace P J, et al. Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 164. College Station, Texas: Texas A & M University (Ocean Drilling Program), 2000: 301-312.
［60］Gieskes J M. Interstitial water studies, Leg 15-Alkalinity, pH, Mg, Ca, Si, PO4, and NH4
[M]// Heezen B C, MacGregor I D, Foreman H P, et al. Initial Reports of the Deep Sea Drilling Project, Volume 20. Washington: U.S. Government Printing Office, 1973: 813-829.
［61］Paull C K, Matsumoto R, Wallace P J, et al. Proceedings of the Ocean Drilling Program, Initial Reports, Volume 164
[M]. College Station, Texas: Texas A & M University (Ocean Drilling Program), 1996: 1-623.
［62］Shipboard Scientific Party. Site 1244
[M]// Tréhu A M, Bohrmann G, Rack F R, et al. Proceedings of the Ocean Drilling Program, Initial Reports, Vol. 204. College Station, Texas: Texas A & M University (Ocean Drilling Program), 2003: 1-132.
［63］Expedition 311 Scientists. Site U1326
[M]// Riedel M, Collett T S, Malone M J, et al. Proc. IODP, 311: Washington, D C:Integrated Ocean Drilling Program Management International, Inc.2006：1-103.
［64］杨涛，蒋少涌，杨竞红，等.孔隙水中NH4+和HPO2-4浓度异常：一种潜在的天然气水合物地球化学勘查新指标
[J].现代地质，2005，19(1)：55-60.

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