CARBON STABLE ISOTOPIC COMPOSITION OF BENTHIC FORAMINIFERS FROM THE NORTH OF THE SOUTH CHINA SEA: INDICATOR OF METHANE-RICH ENVIRONMENT
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摘要: 对南海北部陆坡东沙海域、神狐海域及西沙海槽甲烷渗漏环境和无甲烷渗漏环境87个浅表层沉积物中的底栖有孔虫Uvigerina spp.进行碳同位素分析研究,结果表明,东沙海域δ13C值为-0.52‰~-5.68‰,平均值为-1.41‰,出现明显的负偏移;神狐海域δ13C值介于-0.36‰~-1.10‰,平均值为-0.75‰,未见明显的δ13C值负偏移;西沙海槽δ13C值介于-0.01%~-0.89‰,平均值为-0.45‰;对Uvigerina spp.碳同位素组成与沉积物有机碳(TOC)、甲烷(CH4)间的关系进行探讨,发现δ13C负偏移主要出现在甲烷渗漏环境,发生在末次盛冰期,与溶解无机碳负偏移以及沉积物全样的δ13C值负偏移层位相吻合,有可能作为富甲烷环境的替代指标。Abstract: Carbon stable isotopic composition of benthic foraminifers in piston cores and surface sediments from the north of the South China Sea have been studied. The carbon stable isotope analyses of infaunal species (Uvigerina spp.) revealed a distinction between seep and non-seep foraminifera.Uvigerina spp.collected from Dongsha area (seep environment) exhibited highly variable and strongly depleted δ13C values,ranging from -0.52‰ to -5.68‰ and the mean values -1.41‰; The Uvigerina spp. δ13C values ranged from -0.36‰ to -1.10‰, mean -0.75‰ in Shenhu area(non-seep environment); and δ13C values ranged from -0.01 to -0.89‰, mean -0.45‰ in Xisha Trough (non-seep environment). The relations between δ13C values,organic carbon (TOC) and methane (CH4) content showed that carbon isotopic ratios had a negative excursion trend with methane conent increasing. Negative carbon isotopic excursion of Uvigerina spp. mostly occurred during LGM, when dissolved inorganic carbon of bottom water and δ13C of core sediments were negative excursions. The studies imply that the carbon isotopic excursion may be used to indicate methane-rich environment.
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Key words:
- benthic foraminifera /
- stable isotopes /
- methane seep /
- the north of the South China Sea
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[1] Hill T M, Kennett J P, Valentine D L. Isotopic evidence for the incorporation of methane-derived carbon into foraminifera from modern methane seeps, Hydrate Ridge, Northeast Pacific[J]. Geochimica et Cosmochimica Acta,2004,68(22):4619-4627.
[2] Kennett J P, Cannariato K G, Hendy I L,et al. Carbon isotopic evidence for methane hydrate instability during Quaternary interstadial[J]. Science,2000,288:128-132.
[3] Kennett J P, Cannariato K G, Hendy I L,et al.Role of methane hydrates in late Quaternary climate change:the Clathrate Gun Hypothesi[J]. Am. Geophys.Union,2002,216.
[4] Keigwin L D.Late Pleistocene-Holocene paleoceanography and ventilation of the gulf of California[J].Journal of Oceanography,2002,58:421-432.
[5] Prokopenko A A.Williams D F.Deglacial methane emission signals in the carbon isotopic record of Lake Baikal[J].Earth Planet. Sci. Lett.,2004,218:135-147.
[6] Wefer G, Heinze P M, Berger W H.Clues to ancient methane release[J]. Nature,1994,369:282.
[7] 卢苗安,马宗晋,陈木宏. 倒数第2次冰消期西太平洋边缘海δ13C快速负偏事件[J].第四纪研究, 2002,22(4):349-358.
[LU Miao-an,MA Zong-jin,CHEN Mu-bong.Rapid carbon-is-otop enegative excursion events during the penultimate deglaciation in western Pacific marginal sea areas and their origins[J].Quaternary Sciences,2002,22(4):349-358.]
[8] Akimoto K, Tanaka T, Hattori M,et al.Recent benthic foraminiferal assemblages from the cold seep communities ^ A contribution to the Methane Gas Indicator[C]//Neogene Events in Time and Space. University of Tokyo Press, Tokyo,1994:11-25.
[9] Hill T M, Kennett J P, Spero H J.Foraminifera as indicators of methane-rich environments:a study of modern methane seeps in Santa Barbara Channel, California[J]. Marine Micropaleontology,2003,49(1~2):123-138.
[10] Panieri G.Benthic foraminifera response to methane release in an Adriatic Sea pockmark[J].Rivista Italiana di Paleontologia e Stratigrafia (Milano),2003,109(3):549-562.
[11] Rathburn A E, Levin L A, Held Z,et al.Benthic foraminifera associated with cold methane seeps on the northern California margin:ecology and stable isotopic composition[J]. Marine Micropaleontology,2000,38:247-266.
[12] Rathburn A E, Pérez M E, Martin J B,et al.Relationships between the distribution and stable isotopic composition of living benthic foraminifera and cold methane seep biogeochemistry in Monterey Bay, California[J]. Geochemistry, Geophysics, Geosystems,2003, 4(12):1106.
[13] Sen Gupta B K, Platon E, Bernhard J M,et al.Foraminiferal colonization of hydrocarbon-seep bacterial mats and underlying sediment, Gulf of Mexico slope[J]. Journal of Foraminiferal Research,1997,27:292-300.
[14] 成鑫荣,汪品先,黄宝琦,等,南海表层沉积中有孔虫壳体的碳同位素研究及其意义[J].科学通报,2005, 50(1):48-52.
[CHENG Xin-rong,WANG Pin-xian,HUANG Bao-qi.Carbon isotope of foraminiferal tests in South China Sea surface sediments and significance[J].Chinese Science Bulletin,2005,50(1):48-52.]
[15] 翦知湣,王律江.南海晚第四纪表层古生产力与东亚季风变迁[J].第四纪研究,1999,1:32-40.[JIAN Zhi-min,WANG Lü
;-jiang.Late Quaternary surface productivity and East Asian monsoon changes in the South China Sea[J].Quaternary Sciences,1999,1:32-40.]
[16] 钱建兴.晚第四纪以来南海古海洋学研究[M].北京:科学出版社,1999:131-142.[QIAN Jian-xing.Paleoceanography of the South China Sea Since Late Quaternary[M].Beijing:Science Press,1999:131
-142.]
[17] 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[C]//Proceedings of the Ocean Drilling Program,Scientific Results,2000,164:301-312.
[18] Valentine D L. Biogeochemistry and microbial ecology of methane oxidation in anoxic environments:A review[J]. Antonie von Leeuwenhoeck,2002,81:271-282.
[19] 陈芳,苏新,Nurnberg D,等.南海东沙海域末次冰期最盛期以来的沉积特征[J].海洋地质与第四纪地质,2006,26(6):9-17.
[CHEN Fang,SU Xin,Nurnberg D,et al.Sedimentation since last glaciation maximum in Dongsha area of the South China Sea[J].Marine Geology and Quaternary Geology,2006,26(6):9-17.]
[20] 汪品先. 十五万年来的南海[M].上海:同济大学出版社, 1995.[WANG Pin-xian.South China Sea Since 150 ka[M].Shanghai:Tongji University Press,1995.]
[21] MacDonald G J. The long-2term impacts on increasing atmospheric arbon dioxide levels[M]. Ballinger,Cambridge,MA,1982.
[22] Hamberlain J W, Foley H M, MacDonald G J,et al.Climate effects of minor atmospheric constituents[C]//Carbon Dioxide Review, Oxford Univ.Press New,2003.
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