北印度洋海底冷泉流体活动研究进展

Recent progress on submarine cold seep activity of the northern Indian Ocean

冷泉是继洋中脊热液之后,在海底发现的又一种流体渗漏类型,是20世纪80年代以来海洋地质领域最引人注目的发现之一。北印度洋欧亚大陆边缘构造活跃,印度东西两侧发育巨厚沉积层,极易孕育冷泉活动。目前,已在莫克兰和孟加拉湾地区海底观测到多处活动冷泉,对它们的研究为深入了解海底冷泉流体活动的资源环境效应打开了新的窗口。文章以北印度洋典型冷泉区——莫克兰和孟加拉湾地区为例,综述了该区海底冷泉流体来源、相关沉积环境和触发机制,着重阐述了:1)莫克兰地区最小含氧带内外冷泉活动的沉积记录和地震触发冷泉的机制及环境响应;2)孟加拉湾地区海底天然气水合物分解在碳酸盐岩中的记录。进一步指出了北印度洋海底冷泉活动研究中遇到的挑战和未来工作中需给予重视的科学问题。

The discovery of cold hydrocarbon seeps has been one of the most important achievements of marine geology besides hydrothermal vents during the last half century.Gravitational and tectonic forces are common in the northern Indian Ocean,which results in methane seepages on the seafloor.Recent studies of cold hydrocarbon seeps from Makran and Bay of Bengal areas have made important progresses and these findings have opened a window for understanding the resource and environmental issues of submarine cold seeps.An overview about the present knowledge of the northern Indian Ocean is provided,which concentrates on1)sedimentary records of the cold seep activities in the Makran area both inside and outside of the oxygen minimum zone and the cold seep activity triggered by earthquake activity,and2)the dissociation of gas hydrate in the Bay of Bengal that recorded in the carbonate rocks.Furthermore,challenges of seep research in the northern Indian Ocean and scientific problems in the future are discussed.