南海北部东沙群岛HD196站位地球化学特征及其对水合物的指示

南海北部是中国海上油气的重要基地,也是中国天然气水合物调查的首选地区。对南海北部东沙群岛附近具有BSR特征的HD196站位沉积物样品的地球化学特征进行综合分析,得到以下结果:柱状样沉积物的常量元素的分布具有分段性,且与沉积物孔隙水中的离子浓度和甲烷含量的变化趋势相一致,可能对其下面是否存在天然气水合物有指示意义;同时柱状样沉积物孔隙水中离子浓度的变化与世界上发现天然气水合物地点的孔隙水离子浓度的变化一致。HD196站位的地质条件表明本站位具有天然气水合物形成的温压条件、气源条件和构造条件,因此在本站位的下面赋存天然气水合物的可能性比较大,在此进一步工作有可能取得天然气水合物勘查的突破。

Geochemical Characteristics of Sediments at Site HD196 in Dongsha Islands, the North of the South China Sea, and Their Implication for Gas Hydrates

The north of the South China Sea is the important basement of marine hydrocarbon and the first selection region of the gas hydrate investigation in China.Based on the geochemical results of sediments at site HD196 in Dongsha islands,the features of major elements show the tendency of two sections,and just consistent with the change of the ion content of pore water and methane in the sediment.Meanwhile,the change of the ion content of pore waters at the site has the same characteristics as that at other sites where the gas hydrate has been discovered.Furthermore,the geological condition of the region shows that the P-T enviorment,gas source conditions and tectonic settings could provide suitable thermodynamic condition for the formation of gas hydrates in the site.Therefore,there may be gas hydrates below the site,and further work will lead to a breakthrough in the exploration of the gas hydrate.