HR: 16:00h
AN: B54C-01    [Abstracts]
TI: Manned submersible observations at cold seeps in the North Anatolian Fault zone, Sea of Marmara
AU: Henry, P
EM: henry@cdf.u-3mrs.fr
AF: CEREGE/Collège de France, Europôle de l'Arbois BP80, Aix-en-Provence, 13545, France
AU: * Zitter, T A
EM: zitter@cdf.u-3mrs.fr
AF: CEREGE/Collège de France, Europôle de l'Arbois BP80, Aix-en-Provence, 13545, France
AU: Le Pichon, X
EM: lepichon@cdf.u-3mrs.fr
AF: CEREGE/Collège de France, Europôle de l'Arbois BP80, Aix-en-Provence, 13545, France
AU: Sengor, C A
EM: sengor@itu.edu.tr
AF: Istanbul Technical University, Faculty of Mines, Geology department, Maslak, Istanbul, 34469, Turkey
AU: Gorur, N
EM: naci@aksanyapi.com
AF: Istanbul Technical University, Faculty of Mines, Geology department, Maslak, Istanbul, 34469, Turkey
AU: Gasperini, L
EM: luca.gasperini@bo.ismar.cnr.it
AF: ISMAR, Via Gobetti 101, Bologna, 40129, Italy
AU: Géli, L
EM: louis.geli@ifremer.fr
AF: IFREMER, Marine Geosciences department BP70, Plouzané, 29280, France
AU: Tryon, M D
EM: mtryon@ucsd.edu
AF: Scripps Institution of Oceanography, UCSD, 9500 Gilman Dr., 0244, La Jolla, CA 92093- 0244, United States
AU: Shipboard Scientific Party, M
AB: Cold seeps in the Sea of Marmara are associated with active deformation within the North Anatolian Fault system, a transcurrent plate boundary. The Marnaut cruise of Ifremer RV L'Atalante took place in May-June 2007 with objectives (1) to locate gas outflow sites through acoustic means; (2) to better define the relations between active faults and fluid outlets using the Nautile manned submersible; (3) to sample these fluids to determine their nature and origin; (4) to install instruments to monitor the activity of three fluid outflow sites as well as the microseismicity during several months; (4) to sample carbonate crusts, testimonies of the passed activity of fluid outflow; (5) to evaluate the impact of fluid outflow on the present biological and microbiological activity on the seafloor and within the water column; (6) to sample through coring the sediment deposited during the previous earthquakes. Several new zones of fluid emission were found including unexpected locations in areas previously explored with ROV and deep towed cameras. In the Cinarcik Basin, seeps were found along outcrops of Paleozoic sedimentary rocks at the base of the fault-controlled northern cliff, and on en-echelon normal faults extending over the southern slope. In the Tekirdag Basin, bubble emissions were found at the base of the Ganos cliff along NW-SE tension gashes affecting Eocene turbidites of the Kesan formation. On the topographic highs the most active fluid emission sites were found on the top of NE-SW anticlinal ridges at some distance (100-2000 m) from the main fault trace. Active fault scarps were explored at several locations. Very little cold seep activity and no evidence for seafloor rupture from 1999 or 1912 earthquakes was found at the entrance of the Ganos and Izmit Gulf. Observations suggest basement structures along the edges of the subsiding basins and compressive structures on the topographic highs contribute to fluid channeling and expulsion. Cold seeps are found along the main fault scarps in Cinarcik and Tekirdag basins, but also along less prominent fault zones along the opposite side of the basins. The strike-slip fault segment cutting the Central High (west of Istanbul) has comparatively little cold seep activity and we wonder whether this relates to the seismic gap there.
DE: 3004 Gas and hydrate systems
DE: 3080 Submergence instruments: ROV, AUV, submersibles
DE: 8106 Continental margins: transform
SC: Biogeosciences [B]
MN: 2007 Fall Meeting