FN Archimer Export Format PT J TI Free gas and gas hydrates from the Sea of Marmara, Turkey Chemical and structural characterization BT AF BOURRY, Christophe CHAZALLON, Bertrand CHARLOU, Jean-Luc DONVAL, Jean-Pierre RUFFINE, Livio HENRY, Pierre GELI, Louis CAGATAY, M. Namik INAN, Sedat MOREAU, Myriam AS 1:1;2:2;3:1;4:1;5:1;6:3;7:1;8:4;9:5;10:6; FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:; C1 IFREMER, Ctr Brest, Dept Marine Geosci, Lab Geochim & Metall, F-29280 Plouzane, France. Univ Lille 1, Lab Phys Lasers Atomes & Mol PhLAM, CERLA, UMR CNRS 8523, F-59655 Villeneuve Dascq, France. Aix Marseille Univ, CEREGE, CNRS, Coll France, F-13545 Aix En Provence, France. Istanbul Tech Univ, TR-34469 Istanbul, Turkey. Inst Earth & Marine Sci, TUBITAK Marmara Res Ctr, Gebze, Turkey. Univ Lille 1, Lab Spectrochim Infrarouge & Raman, UMR CNRS 8516, F-59655 Villeneuve Dascq, France. C2 IFREMER, FRANCE UNIV LILLE, FRANCE UNIV AIX MARSEILLE, FRANCE UNIV TECH ISTANBUL, TURKEY INST EARTH & MARINE SCI, TURKEY UNIV LILLE, FRANCE SI BREST IN WOS Ifremer jusqu'en 2018 copubli-france copubli-univ-france copubli-int-hors-europe copubli-sud IF 3.407 TC 88 TU Aix-Marseille université Centre national de la recherche scientifique Collège de France Institut de recherche pour le développement Université Lille 1 - Sciences technologies Université Lille 2 - Droit et Santé École nationale supérieure de chimie de Lille UR https://archimer.ifremer.fr/doc/2009/publication-6844.pdf LA English DT Article CR MARNAUT BO L'Atalante DE ;Isotopes;Thermogenic gas;Gas bubbles;Gas hydrate;Sea of Marmara AB Gas hydrates and gas bubbles were collected during the MARNAUT cruise (May-June 2007) in the Sea of Marmara along the North Anatolian Fault system, Turkey. Gas hydrates were sampled in the western part of the Sea of Marmara (on the Western High), and three gas-bubble samples were recovered on the Western High, the Central High (center part of the Sea of Marmara) and in the Cinarcik Basin (eastern part of the Sea of Marmara). Methane is the major component of hydrates (66.1%), but heavier gases such as C-2, C-3, and i-C-4 are also present in relatively high concentration. The methane contained within gas hydrate is clearly thermogenic as evidenced by a low C-1/C-2 + C-3 ratio of 3.3, and carbon and hydrogen isotopic data (delta C-13(CH4) of -44.1 parts per thousand PDB and delta D-CH4 of -219 parts per thousand SMOW). A similar signature is found for the associated gas bubbles (C-1/C-2 + C-3 ratio of 24.4, delta C-13(CH4) of -44.4 parts per thousand PDB) which have the same composition as natural gas from K. Marmara-af field. Gas bubbles from Central High show also a thermogenic origin as evidenced by a C-1/C-2 + C-3 ratio of 137, and carbon and hydrogen isotopic data (delta C-13(CH4) of -44.4 parts per thousand PDB and delta D-CH4 of -210 parts per thousand SMOW), whereas those from the Cinarcik Basin have a primarily microbial origin (C-1/C-2 + C-3 ratio of 16,600, delta C-13(CH4) of -64.1 parts per thousand PDB). UV-Raman spectroscopy reveals structure II for gas hydrates, with CH4 trapped in the small (5(12)) and large (5(12)6(4)) cages, and with C2H6, C3H8 and i-C4H10 trapped in the large cages. Hydrate composition is in good agreement with equilibrium calculations, which confirm the genetic link between the gas hydrate and gas bubbles at Western High and the K.Marmara-af offshore gas field located north of the Western High. We calculate the characteristics of the hydrate stability zone at Western High and in the Cinarcik Basin using the CSM-GEM computer program. The base of the structure II hydrate stability field is at about 100 m depth below the seafloor at the Western High site, whereas in the Cinarcik Basin, P-Tconditions at the sea floor correspond to the uppermost range for structure I hydrate formation from microbial gas. PY 2009 PD JUL SO Chemical Geology SN 0009-2541 PU Elsevier VL 264 IS 1-4 UT 000267379900017 BP 197 EP 206 DI 10.1016/j.chemgeo.2009.03.007 ID 6844 ER EF