|Author(s)||Garcia Garcia Ana1, 2, Orange D1, 2, Lorenson T3, Radakovitch O4, Tesi T.5, Miserocchi S5, Berne Serge6, Friend P.L.7, Nittrouer C8, Normand Alain6|
|Affiliation(s)||1 : Univ Calif Santa Cruz, Dept Earth Sci, Santa Cruz, CA 95064 USA.
2 : AOA Geophys Inc, Moss Landing, CA 95039 USA.
3 : US Geol Survey, Menlo Pk, CA 94025 USA.
4 : CEREGE, F-13545 Aix En Provence, France.
5 : CNR, ISMAR, I-40129 Bologna, Italy.
6 : IFREMER, F-29280 Plouzane, France.
7 : Univ Washington, Sch Oceanog, Seattle, WA 98195 USA.
8 : Univ Southampton, Sch Ocean & Earth Sci, SOC, Southampton SO14 3ZH, Hants, England.
|Source||Marine Geology (0025-3227) (Elsevier), 2006-12 , Vol. 234 , N. 1-4 , P. 215-231|
|WOS© Times Cited||19|
|Keyword(s)||Gulf of Lions, Rhone prodelta, Flood deposits, Biogenic methane, Shallow gas|
|Abstract||Sediment cores acquired in 2004 off the Rhone prodelta show consistent anomalous methane concentrations of up to 87,440 ppm. Methane compositional and isotopic data support a biogenic origin, although there are a few sites that show strongly depleted delta C-13 values (-53%o PDB) suggesting a mixed source for the gas (biogenic and thermogenic). Anomalous methane concentrations (samples with more than 90 ppm) are discussed and integrated with organic carbon data, sedimentary rates and ADCP profiles. Highest gas concentrations were found directly off the river mouth (20-40 m water depth) and where the IFREMER models point to the thickest accumulation (> 2 m) in response to the Rhone flood event. In areas unaffected by the high flux of organic matter and rapid/thick flood deposition, or in between flood events, the conditions for methanogenesis and gas accumulation have not been met; in these areas, the physical and biological reworking of the surficial sediment may effectively oxidize and mineralize organic matter and limit bacterial methanogenesis in the sub-surface. We propose that in the Rhone prodelta flood deposits deliver significant amounts of terrigenous organic matter that can be rapidly buried, effectively removing this organic matter from aerobic oxidation and biological uptake and leading to the potential for methanogenesis with burial.|
Garcia Garcia Ana, Orange D, Lorenson T, Radakovitch O, Tesi T., Miserocchi S, Berne Serge, Friend P.L., Nittrouer C, Normand Alain (2006). Shallow gas off the Rhone prodelta, Gulf of Lions. Marine Geology, 234(1-4), 215-231. Publisher's official version : https://doi.org/10.1016/j.margeo.2006.09.005 , Open Access version : https://archimer.ifremer.fr/doc/00000/2396/