caa a22 4500 463216237 CHVBK 20180405153157.0 cr unu---uuuuu 170326e20070601xx s 000 0 eng 10.1007/s00367-007-0067-1 doi (NATIONALLICENCE)springer-10.1007/s00367-007-0067-1 Understanding shallow gas occurrences in the Gulf of Lions [Elektronische Daten] [A. García-García, T. Tesi, D. Orange, T. Lorenson, S. Miserocchi, L. Langone, I. Herbert, J. Dougherty] New coring data have been acquired along the western Gulf of Lions showing anomalous concentrations of methane (up to 95,700ppm) off the Rhône prodelta and the head of the southern canyons Lacaze-Duthiers and Cap de Creus. Sediment cores were acquired with box and kasten cores during 2004-2005 on several EuroSTRATAFORM cruises. Anomalous methane concentrations are discussed and integrated with organic carbon data. Sampled sites include locations where previous surveys identified acoustic anomalies in high-resolution seismic profiles, which may be related to the presence of gas. Interpretation of the collected data has enabled us to discuss the nature of shallow gas along the Gulf of Lions, and its association with recent sedimentary dynamics. The Rhône 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. Away from the flood-related sediments off the Rhône delta, the organic matter is being reworked and remineralized on its way along the western coast of the Gulf of Lions, with the result that the recent deposits in the canyon contain little reactive carbon. In the southernmost canyons, Lacaze-Duthiers and Cap de Creus, the gas analyses show relatively little shallow gas in the core samples. Samples with anomalous gas (up to 5,000ppm methane) are limited to local areas where the samples also show higher amounts of organic matter. The anomalous samples at the head of the southern canyons may be related to methanogenesis of recent drape or of older sidewall canyon infills. Springer-Verlag, 2007 García-García A. Department of Earth and Planetary Sciences, UCSC, 95064, Santa Cruz, CA, USA aut Tesi T. CNR-ISMAR, 40129, Bologna, Italy aut Orange D. Department of Earth and Planetary Sciences, UCSC, 95064, Santa Cruz, CA, USA aut Lorenson T. USGS, 94025, Menlo Park, CA, USA aut Miserocchi S. CNR-ISMAR, 40129, Bologna, Italy aut Langone L. CNR-ISMAR, 40129, Bologna, Italy aut Herbert I. Geomarine Sciences, AOA Geophysics Inc., 95039, Moss Landing, CA, USA aut Dougherty J. USGS, 94025, Menlo Park, CA, USA aut Geo-Marine Letters Springer-Verlag 27/2-4(2007-06-01), 143-154 0276-0460 27:2-4<143 2007 27 367 https://doi.org/10.1007/s00367-007-0067-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00367-007-0067-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- García-García A. Department of Earth and Planetary Sciences, UCSC, 95064, Santa Cruz, CA, USA aut NATIONALLICENCE 700 1- Tesi T. CNR-ISMAR, 40129, Bologna, Italy aut NATIONALLICENCE 700 1- Orange D. Department of Earth and Planetary Sciences, UCSC, 95064, Santa Cruz, CA, USA aut NATIONALLICENCE 700 1- Lorenson T. USGS, 94025, Menlo Park, CA, USA aut NATIONALLICENCE 700 1- Miserocchi S. CNR-ISMAR, 40129, Bologna, Italy aut NATIONALLICENCE 700 1- Langone L. CNR-ISMAR, 40129, Bologna, Italy aut NATIONALLICENCE 700 1- Herbert I. Geomarine Sciences, AOA Geophysics Inc., 95039, Moss Landing, CA, USA aut NATIONALLICENCE 700 1- Dougherty J. USGS, 94025, Menlo Park, CA, USA aut NATIONALLICENCE 773 0- Geo-Marine Letters Springer-Verlag 27/2-4(2007-06-01), 143-154 0276-0460 27:2-4<143 2007 27 367 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer