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天然气水合物沉积环境出现的岩石矿物主要为碳酸盐岩、黄铁矿、石膏等。自生碳酸盐岩的典型特点为极负的δ~(13)C_(PDB)值(最低可达-70.0‰)、正的δ~(18)O_(PDB)值(+2.5‰～+6.5‰),碳酸盐矿物主要为镁方解石、文石、白云石和菱铁矿。黄铁矿以霉球状、条状为主。石膏则主要为自形晶体,透明。此类自生岩石矿物与甲烷厌氧氧化过程或水合物的形成效应有关。南海沉积物中出现的自生碳酸盐岩、黄铁矿和石膏,其特点与水合物沉积环境中的十分类似,预示了南海可能存在有利于水合物成藏的地球化学过程。
The rock minerals appearing in the gas hydrate deposition environment are mainly carbonate rock, pyrite, gypsum and so on. The typical characteristics of the spontaneous carbonate rocks are extremely negative δ ~ (13) C_ (PDB) values (up to -70.0 ‰) and positive δ ~ (18) O_ (PDB) values from +2.5 ‰ to +6.5 ‰), carbonate minerals are mainly calcite, aragonite, dolomite and siderite. Pyrite to mildew spherical, strip-based. Gypsum is mainly self crystal, transparent. Such authigenic rock minerals are associated with the anaerobic oxidation of methane or the formation of hydrates. The characteristics of spontaneous carbonate rocks, pyrite and gypsum in the sediments of the South China Sea are very similar to those in the hydrate depositional environment, indicating that there may be a geochemical process in the South China Sea conducive to the accumulation of hydrates.