Geochemistry of sediment pore water from Well GMGS2-09 in the southeastern Pearl River Mouth Basin, South China Sea: An indication of gas hydrate occurrence
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摘要:
沉积物孔隙水地球化学是天然气水合物勘探与研究的重要手段。为了探究珠江口盆地东南海域GMGS2-09钻孔的沉积物孔隙水地球化学特征及其对埋藏的天然气水合物的指示意义,我们在前人的研究和认知基础上,通过测试该钻孔沉积物孔隙水的氯离子含量、氢氧同位素和阳离子组成来识别天然气水合物的赋存层位。结果表明GMGS2-09钻孔在9~17、47以及100m处存在氯离子浓度的负异常耦合氧同位素的正异常,指示相应的天然气水合物赋存,其中9~17m层位指示结果与实际取样情况完全一致。此外,采用基于水合物晶格的排盐机理推导的经验公式计算显示水合物饱和度在浅表层(17m)最高约为50%,中间以及底层约为20%。
Abstract:Geochemistry of pore water of marine sediments playes an important role in gas hydrate research. In order to detect the gas hydrater-bearing layers, geochemical characteristics and their implications for buried gas hydrates are studied with pore water collected from the Site GMGS2-09 in the southeastern part of the Pearl River Mouth Basin. Cations, anions, hydrogen and oxygen isotopic compositions are analyzed and studied upon previous researches. Chloride anomalies coupled with increased δ18O in pore water are observed at the depths of 9~17 meter, in which gas hydrate is recovered, 47 meter and 100 meter, which may indicate the presences of gas hydrate-bearing layers. Besides, gas hydrate saturation calculated indicates that it is 50% in depth of 17 m, and about 20% in depth of 47 m and 100 m.
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Key words:
- gas hydrate /
- pore water /
- geochemistry /
- Pearl River Mouth Basin
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