南海北部东沙海域水合物区浅表层沉积物的地球化学特征

邬黛黛; 吴能友; 付少英; 梁金强; 管红香

doi:10.3724/SP.J.1140.2010.05041

南海北部东沙海域水合物区浅表层沉积物的地球化学特征

邬黛黛^1,2,3,
吴能友^1,2,3,
付少英⁴,
梁金强⁴,
管红香^1,2,3

1 中国科学院边缘海地质重点实验室, 中国科学院广州地球化学研究所, 广州 510640;
2 中国科学院可再生能源与天然气水合物重点实验室, 中国科学院广州能源研究所, 广州 510640;
3 中国科学院广州天然气水合物研究中心, 广州 510640;
4 广州海洋地质调查局, 广州 510760

基金项目:

中国科学院广州能源研究所所长创新基金项目(o807r71001)

国土资源部公益性行业科研专项(200811014)

中国科学院知识创新工程重要方向项目(KGCX2-YW-805)

中国科学院边缘海地质重点实验室研究基金(MSGL09-05)

国家重点基础研究发展规划项目(2009CB219506)

详细信息

作者简介:
邬黛黛(1981-),女,博士,副研究员,主要从事海洋地质、地球化学研究,E-mail:wudd@ms.giec.ac.cn

中图分类号: P736.4
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出版历程
- 收稿日期: 2010-01-12
- 修回日期: 2010-06-18

GEOCHEMICAL CHARACTERISTICS OF SHALLOW SEDIMENTS IN THE GAS HYDRATE DISTRIBUTION AREA OF DONGSHA, THE NORTHERN SOUTH CHINA SEA

1. Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, CAS, Gaungzhou 510640, China;
2. Key Laboratory of Renewable Energy and Gas Hydrate, Guangzhou Institute of Energy Conversion, CAS, Guangzhou 510640, China;
3. Guangzhou Center for Gas Hydrate Research, CAS, Guangzhou 510640, China;
4. Guangzhou Marine Geological Survey, Guangzhou 510760, China

摘要

摘要: 对采自南海北部陆坡东沙海域水合物区HD319、HD196A和GC10站位的浅表层沉积物进行了地球化学特征研究。X射线衍射分析和扫描电镜观察表明,沉积物中存在具有天然气水合物和甲烷渗漏指示意义的自生碳酸盐、硫酸盐和黄铁矿。沉积物孔隙水化学组分分析显示,随着埋藏深度加深,SO₄^2-、Ca²⁺、Mg²⁺和Sr²⁺浓度明显降低,CH₄、H₂S浓度的增加,以及Mg²⁺/Ca²⁺和Sr²⁺/Ca²⁺比值急剧增加,与世界上水合物区浅表层沉积物孔隙水中离子浓度异常特征吻合。沉积物顶空气游离烃分析结果和孔隙水化学组分变化,特别是SO₄^2-、H₂S和甲烷含量的急剧变化,说明研究区有丰富的气源,赋存水合物的可能性非常大,同时指示了研究区硫酸盐-甲烷界面(SMI)较浅,位于海底之下8 m左右。
- 天然气水合物 /
- 地球化学特征 /
- 自生矿物 /
- 孔隙水 /
- 顶空气 /
- 南海
Abstract: Geochemical characteristics of the shallow sediments from sites HD319, HD196A and GC10 in Dongsha gas hydrate distribution area, the northern slope of South China Sea was discribed in the present paper. Complicated authigenic minerals were identified by XRD and SEM, such as miscellaneous carbonates, sulphates and pyrite, which consistently indicate the existence of gas hydrate and methane seep in the research area. Chemical analysis of pore water from the sediments showed that the concentrations of SO₄^2-, Ca²⁺, Mg²⁺ and Sr²⁺ decrease clearly,whereas CH₄ and H₂S as well as the ratios of Mg²⁺/Ca²⁺ and Sr²⁺/Ca²⁺ increase sharply as the depth increases. These geochemical characteristics are similar to the chemical compositions abnormalities in pore water of the shallow sediments,where gas hydrate forms in the other parts of the world. There should be a great amount of gas sources in the research area,based on the occurrence of free hydrocarbon in the headspace gas and the distribution pattern of chemical compositions in the sediments, specially the concentrations of SO₄^2-, H₂S and CH₄ which changed sharply with depth. Furthermore, the results strongly suggest that there should be gas hydrates underneath, and the sulphate-methane interface (SMI) should be shallow, about 8m below the seafloor in the research area.
- gas hydrate /
- geochemical characteristics /
- authgenic minerals /
- pore water /
- headspace gas /
- the South China Sea

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