Geochemistry of gas hydrate accumulation offshore NE Sakhalin Island (the Sea of Okhotsk): results from the KOMEX-2002 cruise.

Matveeva, T., Soloviev, V., Wallmann, Klaus , Obzhirov, A., Biebow, N., Poort, J., Salomatin, A. and Shoji, H. (2003) Geochemistry of gas hydrate accumulation offshore NE Sakhalin Island (the Sea of Okhotsk): results from the KOMEX-2002 cruise. Geo-Marine Letters, 23 . pp. 278-288. DOI 10.1007/s00367-003-0150-1.

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Abstract

Geochemical properties of gas hydrate accumulation associated with an active gas vent on the continental slope offshore northeast Sakhalin Island in the Sea of Okhotsk have been investigated. The pore water chemistry data suggest that the gas hydrates (GHs) were formed in an environment of upward-migrating fluid combined with a mechanism of pore water segregation. The upward infiltration of water enriched mainly by Cl− and K+ species appears to occur on the background of earlier diagenesis processes within the gas vent sediments. The GHs were formed from water with chlorinity ranging from 530 to 570 mM. The δ18O and δD of GH water varied from −1.4 to −1.8‰ and from −13 to −18‰, respectively, representing a mix of seawater and infiltrating fluid water. A complex interaction of pore water, water of ascending fluid and segregated pore water during hydrate formation is also supported by water content measurements and observed gas hydrate structure. The direction of segregated water is opposite to upward fluid migration. Decreasing activity of the gas vent is inferred by comparing the present top of the recovered hydrate layer with previous observations.

Document Type: Article
Keywords: Gas hydrates, Sakhalin Island, Sea of Okhotsk, KOMEX-2002 cruise
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/s00367-003-0150-1
ISSN: 0276-0460
Projects: KOMEX
Date Deposited: 18 Feb 2008 17:26
Last Modified: 22 May 2017 13:32
URI: http://oceanrep.geomar.de/id/eprint/7038

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