我国台西南附近构造沉降与沉积作用对气水合物成藏的可能控制

TECTONIC AND SEDIMENTARY CONTROLS ON THE LIKELIHOOD OF GAS HYDRATE OCCURRENCE NEAR WEST AND SOUTH OF TAIWAN IN CHINA

南中国海东北部大陆斜坡带上的海相沉积有适当的沉积厚度,处于适宜形成气水合物的温—压域内,有一定的甲烷生成潜力。从台西南盆地的地震反射记录中,可以观察到气水合物存在的证据——似海底反射(BSR),暗示了气水合物的广泛分布。台西南盆地的构造沉积格架与甲烷的生成和大量气水合物沉积可能存在直接联系;各种快速堆积的沉积体系(如滑塌块体、等深流沉积、浊积扇及三角洲)前缘,是天然气水合物富集的有利沉积相带,其中等深流沉积和滑塌块体推测为最有利气水合物聚集的沉积体。

Marine sediments on the continental slope of the NE South China Sea have appropriate thickness, methane-generating potential, and occur in a suitable pressure temperature regime to host gas hydrate. Evidence for gas hydrate, the bottom simulating reflector (BSR), is observed to the south of Taiwan on reflection seismic records, and can be used to suggest that gas hydrates are widely distributed. The tectono-sedimentary framework south of Taiwan bears directly upon methane generation and the likelihood of the presence of significant gas hydrate deposits.The distribution of contourite, slump block, and the fronts of delta or fans is highly consistent with the distribution of BSR in both areas, so that they are the most favorable facieses for gas hydrate accumulation.