论文部分内容阅读
南海地区天然气水合物资源丰富,针对其分解方式的研究有助于资源的开采.对南海东北部天然气水合物钻探区GMGS08站位岩心沉积物开展沉积学、地球化学分析研究.结果表明:该站位自上而下分布11层含自生碳酸盐岩和双壳碎屑层(其中6层呈粥状沉积)以及2层自生碳酸盐岩灰岩层;各层自生碳酸盐岩除一个样品δ13 C值稍高(-38.85×10-3)外,其他的δ13 C值介于-41.36×10-3~-56.74×10-3,均低于-40.00×10-3,δ18 O值介于2.94×10-3~5.37×10-3,明显偏重,表明其为天然气水合物分解的产物,形成于微生物对甲烷的缺氧氧化作用,甲烷主要源自生物成因;各层自生碳酸盐岩层中的有机质碳同位素负偏明显,最低达-82.44×10-3,可能与微生物活动有关;根据自生碳酸盐岩的分布推断该站位至少发生过6次天然气水合物分解释放,每期次自生碳酸盐岩的差异说明其甲烷通量强弱不同.
The gas hydrate in the South China Sea is rich in natural gas hydrate, and its research on its decomposition mode is helpful for the exploitation of resources. The sedimentology and geochemical analysis of core sediments of GMGS08 in the gas hydrate drilling area in northeastern South China Sea are carried out. The results show that: There are 11 layers of authigenic carbonates and bivalve detritus (of which 6 are porphyritic) and 2 layers of authigenic carbonate rock limestone distributed from top to bottom. Each sample of authigenic carbonate except one The δ13C values of δ13C values were slightly higher (-38.85 × 10-3) than those of -41.36 × 10-3 ~ -56.74 × 10-3, all lower than -40.00 × 10-3, At 2.94 × 10-3 ~ 5.37 × 10-3, which is obviously biased, indicating that it is a product of gas hydrate decomposition, formed by hypoxia oxidation of methane by microorganisms, and methane mainly comes from biological genesis. The carbon isotopes of organic matter in the strata are negatively obvious, with a minimum of -82.44 × 10-3, which may be related to microbial activities. According to the distribution of spontaneous carbonates, at least 6 gas hydrate decomposition and release have been inferred in this stratum. The difference in sub-biogenic carbonates suggests that methane flux varies.