FS Sonne Fahrtbericht / Cruise Report SO177 SiGer 2004, Sino-German Cooperative Project : South China Sea Continental Margin: Geological Methane Budget and Environmental Effects of Methane Emissions and Gashydrates ; cooperative research between IFM-GEOMAR, Kiel, Germany and Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou, Guangdong Province, P.R. China ; 02.06. - 19.07.2004.

Suess, Erwin, ed. and Guangzhou Marine Geological Survey, GMGS, Leibniz-Institut für Meereswissenschaften, IFM-GEOMAR (2005) FS Sonne Fahrtbericht / Cruise Report SO177 SiGer 2004, Sino-German Cooperative Project : South China Sea Continental Margin: Geological Methane Budget and Environmental Effects of Methane Emissions and Gashydrates ; cooperative research between IFM-GEOMAR, Kiel, Germany and Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou, Guangdong Province, P.R. China ; 02.06. - 19.07.2004. Open Access . IFM-GEOMAR Report, 04 . IFM-GEOMAR, Kiel, 154 pp. DOI 10.3289/ifm-geomar_rep_4_2005.

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Abstract

The cooperative research project between Chinese and German leading marine research institutions, the Guangzhou Marine Geological Survey (GMGS) and Leibniz-Institut für Meereswissenschaften Kiel (IFM-GEOMAR) addressed the geological methane budget and environmental effects of methane emissions from gas hydrates along the passive margin of the northern South China Sea. Two areas were surveyed of which the NE area (A) was sampled in great detail, whereas area B, after an initial survey, yielded less promising results. Swath map bathymetry, ocean floor observation by continuous video survey (OFOS) and water column methane distribution pattern provided the basis for locating several sites of ongoing methane venting. Outstanding among these was a methane-derived carbonate structure in water depths of 600-900m. Vast accumulations of vent carbonate debris, pavements and edifices standing above the seafloor characterize this structure. A 30-m high edifice, named Jiu Long Methane Reef, proved to be an active cold vent site with chemosynthetic fauna and bacterial mats. At deep sites ( apprx. 3000m) in and adjacent to the Formosa Canyon methane anomalies in the bottom water and clam colonies also indicate active methane venting. Pore water and gas chemistry on gravity cores indicated rather shallow depths of the sulfate-methane-interface (SMI) and documented chloride anomalies. High methane concentrations (exceeding 10.000 μM) in sediments, which when extrapolated, suggest that saturation might be reached at about 16-24 mbsf at which depths the shallowest gas hydrates might be encountered in the area. The project results contribute directly to several major science policy missions. (1) Documentation of vast amounts of methane emmited from the passive margin of the northern South China Sea is seen as evidence for long-term climate forcing by the greenhouse gas methane. (2) The functioning and significance of deep-sea biota as modulating the greenhouse gas budget is convincingly demonstrated by the vast amounts of methane carbon fixed as authigenic carbonates. (3) Further development of TV-guided deep-sea instrumentation, and above all the retrieval of undecompressed sediments, have again been deomonstrated as high a priority topic
for the future of marine science. (4) The success of the project has demonstrated how international partnerships can efficiently been implemented.

Document Type: Report (Cruise Report)
Additional Information: Chinese ed. in IFM-GEOMAR Library: EXP-SONNE-SO177 (chin.)
Keywords: Meeresgeologie; SiGer 2004; South China Sea; map bathymetry; OFOS; Jiu Long Methane Reef; Formosa Canyon; gas hydrates; methane venting; greenhouse gas budget
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.3289/ifm-geomar_rep_4_2005
ISSN: 1614-6298
Projects: SiGer 2004, South China Sea Continental Margin: Geological Methane Budget and Environmental Effects of Methane Emissions and Gashydrates
Expeditions/Models/Experiments:
Date Deposited: 27 Aug 2009 12:43
Last Modified: 28 Jun 2017 12:48
URI: http://oceanrep.geomar.de/id/eprint/1989

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