南极近海南设得兰陆缘天然气水合物成矿条件与机理

GAS HYDRATE ACCUMULATION CONDITIONS AND MECHANISM ON THE SOUTH SHETLAND CONTINENTAL MARGIN,ANTARCTIC PENINSULA

南设得兰陆缘属于典型的活动型大陆边缘,沟-增生楔-弧前盆地序列发育,具备天然气水合物发育的有利地质构造背景。该区已有的调查资料显示出天然气水合物存在的显著标志——BSR和极性反转特征(或者称为基底反射波,BGR)。研究结果表明,南设得兰陆缘具备形成水合物的充足的气源、适宜的稳定域条件、有利于天然气水合物形成与聚集的沉积体系和特殊地质构造环境,推断南设得兰陆缘以构造型水合物成矿地质模式为主,并以增生楔内甲烷随流体向上迁移形成水合物的模式最为重要。

The South Shetland Continental Margin is a typically active continental margin. The system of trenchaccretionary wedge-forearc basin is well developed, which creates favorable geological and structural background for gas hydrate accumulation. The Survey data shows that this region has significant signs of gas hydrates, such as the occurrence of the Bottom Simulating Reflector（BSR）and polarity reversal characteristics （or the Base of Gas Reflector, BGR）. There are plenty of gas sources, stability regions, depositional systems and specific tectonic environment suitable for gas hydrate formation and accumulation. They fit well with the geological model of hydrate reservoir formation under the control of tectonics. The methane within the accretionary wedge moving upward together with fluids plays important roles.