Multidisciplinary investigation on cold seeps with vigorous gas emissions in the Sea of Marmara (MarsiteCruise): Strategy for site detection and sampling and first scientific outcome
|Author(s)||Ruffine Livio1, Ondreas Helene1, Blanc-Valleron Marie-Madeleine2, Teichert Barbara M. A.3, Scalabrin Carla1, Rinnert Emmanuel1, Birot Dominique1, Croguennec Claire1, Ponzevera Emmanuel1, Pierre Catherine4, Donval Jean-Pierre1, Alix Anne-Sophie1, Germain Yoan1, Bignon Laurent1, Etoubleau Joel1, Caprais Jean-Claude1, Knoery Joel5, Lesongeur Francoise1, Thomas Bastien5, Roubi Angelique1, Legoix Ludovic Nicolas1, 6, Burnard Pete7, 12, Chevalier Nicolas3, 4, Lu Hailong8, Dupre Stephanie1, Fontanier Christophe1, 9, 10, 11, Dissard Delphine4, Olgun Nazli12, Yang Hailin8, Strauss Harald3, Ozaksoy Volkan13, Perchoc Jonathan14, Podeur Christian1, Tarditi Corinne1, Ozbeki Eyyup13, Guyader Vivien1, Marty Bernard7, Madre David G7, Pitel-Roudaut Mathilde1, Grall Celine15, Embriaco Davide16, Polonia Mina17, Gasperini Lucas17, Cagatay M. Namik18, 19, Henry Pierre20, Geli Louis1|
|Affiliation(s)||1 : IFREMER, Dept Ressources Phys & Ecosyst Fond Mer REM, F-29280 Plouzane, France.
2 : Sorbonne Univ, UMR 7207, CR2P, CNRS MNHN, 57 Rue Cuvier, F-75005 Paris, France.
3 : Westfalische Wilhelms Univ Munster, Inst Geol & Palaontol, D-48149 Munster, Germany.
4 : Sorbonne Univ, UPMC, CNRS, IRD,MNHN,LOCEAN,IPSL, Paris, France.
5 : IFREMER, Dept Ressources Biol & Environm RBE, Unite Biogeochim & Ecotoxicol, F-44311 Nantes 03, France.
6 : GEOMAR, Helmholtz Ctr Ocean Res Kiel, Wischhofstr 1-3, D-24148 Kiel, Germany.
7 : Univ Lorraine, CNRS, Ctr Rech Petrog & Geochim, F-54500 Vandoeuvre Les Nancy, France.
8 : Peking Univ, Dept Energy & Sci, Coll Engn, Beijing 100871, Peoples R China.
9 : FORAM, Foraminiferal Study Grp, F-49140 Villeveque, France.
10 : Univ Angers, F-49035 Angers, France.
11 : Univ Bordeaux, CNRS, Environm & Palioenvironm Ocean & Continentaux, UMR 5805, F-33600 Pessac, France.
12 : Istanbul Tech Univ, Eurasia Inst Earth Sci Climate & Marine Sci, TR-34469 Istanbul, Turkey.
13 : Univ Mahallesi, Gen Directorate Mineral Res & Explorat (MTA), Marine & Environm Res Dept, Dumlupmar Bulvari 139, TR-06800 Cankaya, Turkey.
14 : IFREMER, Dyneco BENTHOS, F-29280 Plouzane, France.
15 : Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY USA.
16 : INGV, Via Vigna Murata 605, I-00143 Rome, Italy.
17 : ISMRA, CNR, Ist Sci Marine, Marine Geol, Bologna, Italy.
18 : Istanbul Tech Univ, Fac Mines, EMCOL, 7R-34469 Istanbul, Turkey.
19 : Istanbul Tech Univ, Fac Mines, Dept Geol Engn, 7R-34469 Istanbul, Turkey.
20 : Aix Marseille Univ, CNRS, IRD, Coll France,CEREGE, Aix En Provence, France.
|Source||Deep-sea Research Part Ii-topical Studies In Oceanography (0967-0645) (Pergamon-elsevier Science Ltd), 2018-07 , Vol. 153 , P. 36-47|
|WOS© Times Cited||7|
|Keyword(s)||Acoustic survey, Authigenic carbonates, Biogeochemistry, Chemical analyses, Cold seeps, Dissolved major elements, Fluid seepage, Geology, In situ Raman analysis, Methane, ROV dives|
MarsiteCruise was undertaken in October/November 2014 in the Sea of Marmara to gain detailed insight into the fate of fluids migrating within the sedimentary column and partially released into the water column. The overall objective of the project was to achieve a more global understanding of cold-seep dynamics in the context of a major active strike-slip fault. Five remotely operated vehicle (ROV) dives were performed at selected areas along the North Anatolian Fault and inherited faults.
To efficiently detect, select and sample the gas seeps, we applied an original procedure. It combines sequentially (1) the acquisition of ship-borne multibeam acoustic data from the water column prior to each dive to detect gas emission sites and to design the tracks of the ROV dives, (2) in situ and real-time Raman spectroscopy analysis of the gas stream, and (3) onboard determination of molecular and isotopic compositions of the collected gas bubbles. The in situ Raman spectroscopy was used as a decision-making tool to evaluate the need for continuing with the sampling of gases from the discovered seep, or to move to another one. Push cores were gathered to study buried carbonates and pore waters at the surficial sediment, while CTD-Rosette allowed collecting samples to measure dissolved-methane concentration within the water column followed by a comparison with measurements from samples collected with the submersible Nautile during the Marnaut cruise in 2007.
Overall, the visited sites were characterized by a wide diversity of seeps. CO2- and oil-rich seeps were found at the westernmost part of the sea in the Tekirdag Basin, while amphipods, anemones and coral populated the sites visited at the easternmost part in the Cinarcik Basin. Methane-derived authigenic carbonates and bacterial mats were widespread on the seafloor at all sites with variable size and distributions. The measured methane concentrations in the water column were up to 377 μmol, and the dissolved pore-water profiles indicated the occurrence of sulfate depleting processes accompanied with carbonate precipitation. The pore-water profiles display evidence of biogeochemical transformations leading to the fast depletion of seawater sulfate within the first 25-cm depth of the sediment. These results show that the North Anatolian Fault and inherited faults are important migration paths for fluids for which a significant part is discharged into the water column, contributing to the increase of methane concentration at the bottom seawater and favoring the development of specific ecosystems.