Tracing the Paleo sulfate‐methane transition zones and H2S seepage events in marine sediments: An application of C‐S‐Mo systematics
Tracing the Paleo sulfate‐methane transition zones and H2S seepage events in marine sediments: An application of C‐S‐Mo systematics
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DOI：
10.1029/2012gc004288
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发表时间：
2012-10
期刊：
影响因子：
3.7
通讯作者：
A. Peketi;A. Mazumdar (corresponding author);R. K. Joshi;D. J. Patil;P. L. Srinivas;A. M. Dayal
中科院分区：
文献类型：
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作者：
A. Peketi;A. Mazumdar (corresponding author);R. K. Joshi;D. J. Patil;P. L. Srinivas;A. M. Dayal
微生物介导的甲烷厌氧氧化(AOM)与硫酸盐甲烷过渡带(SMTZ)中硫酸盐的消耗是一种被广泛记录的生物地球化学反应，对大气CH4收支、海洋碳循环和沉积物孔隙流体组成具有深远的影响。在海洋沉积/岩石记录中识别古SMTZ，可以揭示古甲烷通量的变化和冷渗漏(H_2S+CH_4)事件在地质时代的发生。在这里，我们给出了孟加拉湾甲烷水合物矿床上两个沉积岩芯的碳酸盐碳、黄铁矿硫和钼的分析结果。结果表明，同位素贫化碳酸盐碳与富硫黄铁矿密切伴生，将古SMTZ限制在沉积柱内。此外，钼浓度的异常富集指示了硫化氢渗漏事件。在这里，我们提出了一种利用C-S-Mo系统学来破译海洋沉积物和岩石中的古SMTZ的地球化学工具。
Microbially mediated anaebic oxidation of methane (AOM) coupled with sulfate consumption within the sulfate methane transition zone (SMTZ) in marine sediments is a widely recorded biogeochemical reaction and has profound influence on the atmospheric CH4budget, marine carbon cycle and composition of sediment pore fluids. Recognizing the paleo‐SMTZs in the marine sediments/rock records can throw light on the variation of paleo‐methane fluxes and occurrences of cold seep (H2S + CH4) events through geologic time. Here, we present results from carbonate carbon, pyrite sulfur and molybdenum analyses for two sediment cores overlying the methane hydrate deposits in the Bay of Bengal. The results show intimate association of isotopically depleted carbonate carbon and enriched pyrite sulfur, constraining the paleo SMTZ within the sediment column. In addition, anomalous enrichments of Mo concentrations indicate hydrogen sulfide seepage events. Here, we propose a geochemical tool using C‐S‐Mo sytematics to decipher the paleo‐SMTZs in marine sediments and rocks.