摘要
对东沙群岛海域HD170和HD196A两个站位,通过系统的顶空气和孔隙水离子取样测试,对柱状样沉积物和底层水中游离甲烷的含量和沉积物孔隙水的离子组成特征以及孔隙水的来源进行了分析。游离气的分析表明,多数沉积物样品中游离甲烷的含量小于20μL/kg,但在HD196A站位,随着沉积物在海底以下埋深的增加,其中的游离甲烷含量迅速增加,在754～774cm,沉积物中游离甲烷的含量达到了7468．66μL/kg,推测其下存在巨大的烃类供应源。孔隙水的^(86)Sr/^(87)Sr同位素测试显示,本文所研究的两个站位沉积物孔隙水来源于正常的海洋沉积过程,而δ^(11)B的特征表明,沉积物中存在着与海水交换的吸附水,并且HD170站位的交换更多。柱状样沉积物孔隙水中,Ca^(2+)、Mg^(2+)与SO^(-2)_4浓度表现出随着深度增加而明显降低的趋势,其中HD196A站位的硫酸盐甲烷界面小于10mbsf,暗示了该站位深部很可能赋存天然气水合物。
The cores of HD170 and HD196A were collected from Dongsha Area, South China Sea, and the analysis were carried on the concentration of free methane by headspace gases and of Cl^- ,SO4^2- ,Ca^2＋ ,Mg^2＋ and B^3＋ from pore water and on the compositions of ^86Sr/^87Sr and δ^11B, respectively. There is a high free methane composition, about 7468.66μL/kg, in 754- 774cm of HD196A, which indicates a huge hydrocarbons sources. The profiles of SO4^2-, Ca^2 ＋ , Mg^2＋ and SO4^2-/Cl^- and Mg^2＋/Ca^2＋ show that there are probably gas hydrate. And the isotope of ^86Sr/^^87Sr and δ^11B suggests that there maybe is seawater source of pore water and some absorbed water. At the end, the author analysized the potential of gas hydrate in Dongsha Area, South China Sea.
出处
《南海地质研究》
2005年第1期24-32,共9页
Gresearch of Eological South China Sea
