Early Diagenesis Records and Pore Water Composition of Methane-Seep Sediments from the Southeast Hainan Basin, South China Sea

Several authigenic minerals were identified by XRD and SEM analyses in shallow sediments from the Southeast Hainan Basin, on the northern slope of South China Sea. These minerals include miscellaneous carbonates, sulphates, and framboidal pyrite, and this mineral assemblage indicates the existence o...

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Published inJournal of Geological Research Vol. 2011; no. 2011; pp. 1 - 10
Main Authors Wu, Daidai, Wu, Nengyou, Ye, Ying, Zhang, Mei, Liu, Lihua, Guan, Hongxiang, Cong, Xiaorong
Format Journal Article
LanguageEnglish
Published Cairo, Egypt Hindawi Puplishing Corporation 01.12.2011
Hindawi Publishing Corporation
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Summary:Several authigenic minerals were identified by XRD and SEM analyses in shallow sediments from the Southeast Hainan Basin, on the northern slope of South China Sea. These minerals include miscellaneous carbonates, sulphates, and framboidal pyrite, and this mineral assemblage indicates the existence of gas hydrates and a methane seep. The assemblage and fabric features of the minerals are similar to those identified in cold-seep sediments, which are thought to be related to microorganisms fostered by dissolved methane. Chemical composition of pore water shows that the concentrations of SO42-, Ca2+, Mg2+, and Sr2+ decrease clearly, and the ratios of Mg2+ to Ca2+ and Sr2+ to Ca2+ increase sharply with depth. These geochemical properties are similar to those where gas hydrates occur in the world. All results seem to indicate clearly the presence of gas hydrates or deep water oil (gas) reservoirs underneath the seafloor.
ISSN:1687-8833
1687-8841
DOI:10.1155/2011/592703