海洋学研究 ›› 2013, Vol. 31 ›› Issue (3): 1-7.

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甲烷流体活动与沉积物中碳、氮同位素组成响应——南海东北部海洋IV号地区研究

于晓果1,2, 金肖兵1,2, 姚旭莹1,2, 龚建明3   

  1. 1.国家海洋局 海底科学重点实验室,浙江 杭州 310012;
    2.国家海洋局 第二海洋研究所,浙江 杭州 310012;
    3.国家地质调查局 青岛海洋地质研究所, 山东 青岛 266670
  • 收稿日期:2012-04-30 修回日期:2013-01-08 出版日期:2013-09-15 发布日期:2022-11-29
  • 作者简介:于晓果(1964-),女,山东潍坊市人,研究员,主要从事海洋地球化学与同位素地球化学方面的研究。E-mail: yuxiaoguo@sio.org.cn
  • 基金资助:
    国家自然科学基金项目资助(40576059,40976039);浙江省测试科技计划项目资助(2008F70047)

The stable isotopic composition of sediments in methane fluid flowing area, Haiyang IV, the northern part of South China Sea

YU Xiao-guo1,2, JIN Xiao-bing1,2, YAO Xu-ying1,2, GONG Jian-ming3   

  1. 1. Key Laboratory of Submarine Geosciences, SOA, Hangzhou 310012, China;
    2. The Second Institute of Oceanography, SOA, Hangzhou 310012, China;
    3. Qingdao Institute of Marine Geology of China Geology Survey, Qingdao 266071, China
  • Received:2012-04-30 Revised:2013-01-08 Online:2013-09-15 Published:2022-11-29

摘要: 南海东沙群岛东北部海洋IV号地区GC16站重力柱状沉积物中的有机碳、总氮,以及自生碳酸盐岩矿物的无机碳同位素组成分析结果表明,甲烷流体活动区硫酸盐甲烷转换带(SMTZ—sulfate methane transition zone)是重要的生物地球化学界面,该带内沉积物中有机碳、氮与无机碳同位素组成变化明显。GC16站SMTZ上界面以下的沉积物中有机碳、氮同位素组成分别比其上的沉积物负偏1.4‰PDB和0.93‰,反映该带内甲烷缺氧氧化作用(AOM—anaerobic oxidation of methane)与氨氧化作用发育。无机碳同位素组成表明SMTZ界面之下沉积物中的自生碳酸盐岩矿物为以微生物为媒介的甲烷驱动成因,地质历史时期(至柱状沉积物底部沉积时期)曾发生过2次较强烈的CH4流体活动;目前该区甲烷流体活动较弱,甲烷流体影响深度与SMTZ上界面一致,未能到达海底。

关键词: 稳定位素组成, SMTZ, AOM, 氨氧化作用

Abstract: Sediments from the site GC16 of Haiyang IV, the South China Sea show anomalous values of δ13Corg, δ15N and δ13Cinorg. The sulfate methane transition zone (SMTZ) is a key biochemical interface in CH4 fluid flowing area. The values of δ13Corg and δ15N show obviously depleted in STMZ. Comparing with the date above the STMZ, depleted 1.4‰PDB and 0.93‰ respectively within the zone. The data of δ13Cinorg also identify the authigenic carbonates as microbially-mediated methane-derived precipitates. The 2 times of vigorous methane-rich fluid expulsion had occurred since the bottom sediments deposition of the core. The depth of methane fluid arriving coincident with the up limited of STMZ.

Key words: stable isotopic composition, SMTZ, AOM, ammonia oxidation

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