HR: 1340h
AN: OS33B-1470    [Abstracts]
TI: Cold Seeps and Near-Surface Gas Hydrates Offshore Georgia, Eastern Black Sea
AU: Klaucke, I
EM: iklaucke@ifm-geomar.de
AF: Leibniz-Institute of Marine Sciences IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Sahling, H
EM: hsahling@uni-bremen.de
AF: Research Centre Ocean Margins Bremen University, Postbox 330440, Bremen, 28334 Germany
AU: * Weinrebe, W
EM: wweinrebe@ifm-geomar.de
AF: Leibniz-Institute of Marine Sciences IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Blinova, V
EM: vblinova@mail.ru
AF: Dept. Geology and Geochemistry Faculty of Geological Sciences, Moscow State University, Moscow, 110900 Russian Federation
AU: Buerk, D
EM: dbuerk@ifm-geomar.de
AF: Leibniz-Institute of Marine Sciences IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148 Germany
AU: Lursmanashvili, N
EM: nona@rambler.ru
AF: Seismometrical Laboratory, Tbilissi State University, Tbilissi, 0000 Georgia
AU: Bohrmann, G
EM: gbohrmann@uni-bremen.de
AF: Research Centre Ocean Margins Bremen University, Postbox 330440, Bremen, 28334 Germany
AB: Multibeam bathymetry and high-resolution deep-towed sidescan sonar mapping allowed identifying several gas seeps and near-surface gas hydrate deposits in 850-900 metres water depth on the continental slope offshore Batumi, Georgia (Eastern Black Sea). Most of the seeps are located on a broad ridge named Kobuleti Ridge separating two canyons: the Supsa canyon north of the ridge and the deeply incised central canyon south of it. The southern wall of this canyon also shows signs for gas seeps. Gas seeps are shown by acoustic anomalies in the water column on raw sonar records and as high backscatter intensity area on processed data. The seeps on Kobuleti Ridge are characterised by carbonate deposits at the centre and a much wider area where gas hydrates are present. Fractures of a NW-SE direction are present at the seeps site and are probably related to the formation and decomposition of gas. Individual sites of gas emission apparently exert their influence for a circular area of up to 40-m in diameter. Gas geochemistry from gravity cores shows high gas content and a mixture of biogenic and thermogenic gases together with the presence of gas hydrates. The seeps offshore Georgia are of a new type of cold seeps in the Black Sea in addition to shallow water seeps of biogenic gas and deep water mud volcanoes. They are located in deep water within the zone of gas hydrate stability and are probably characterised by a very high gas flux from depth resulting and the coexistence of gas hydrates and free gas. These seeps show great similarity with gas hydrate deposits and cold seeps on Hydrate Ridge offshore Oregon.
DE: 1050 Marine geochemistry (4835, 4845, 4850)
DE: 3004 Gas and hydrate systems
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 4825 Geochemistry
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005