caa a22 4500 463216245 CHVBK 20180405153157.0 cr unu---uuuuu 170326e20070601xx s 000 0 eng 10.1007/s00367-007-0068-0 doi (NATIONALLICENCE)springer-10.1007/s00367-007-0068-0 Seismic expression of gas and gas hydrates across the western Black Sea [Elektronische Daten] [Irina Popescu, Gilles Lericolais, Nicolae Panin, Marc De Batist, Hervé Gillet] This study is a synthesis of gas-related features in recent sediments across the western Black Sea basin. The investigation is based on an extensive seismic dataset, and integrates published information from previous local studies. Our data reveal widespread occurrences of seismic facies indicating free gas in sediments and gas escape in the water column. The presence of gas hydrates is inferred from bottom-simulating reflections (BSRs). The distribution of the gas facies shows (1) major gas accumulations close to the seafloor in the coastal area and along the shelfbreak, (2) ubiquitous gas migration from the deeper subsurface on the shelf and (3) gas hydrate occurrences on the lower slope (below 750m water depth). The coastal and shelfbreak shallow gas areas correspond to the highstand and lowstand depocentres, respectively. Gas in these areas most likely results from in situ degradation of biogenic methane, probably with a contribution of deep gas in the shelfbreak accumulation. On the western shelf, vertical gas migration appears to originate from a source of Eocene age or older and, in some cases, it is clearly related to known deep oil and gas fields. Gas release at the seafloor is abundant at water depths shallower than 725m, which corresponds to the minimum theoretical depth for methane hydrate stability, but occurs only exceptionally at water depths where hydrates can form. As such, gas entering the hydrate stability field appears to form hydrates, acting as a buffer for gas migration towards the seafloor and subsequent escape. Springer-Verlag, 2007 Popescu Irina Renard Centre of Marine Geology (RCMG), University of Ghent, Krijgslaan 281 S8, 9000, Ghent, Belgium aut Lericolais Gilles IFREMER Brest, DRO/GM LES, B.P. 70, 29280, Plouzané, France aut Panin Nicolae GeoEcoMar Bucharest, Str. D. Onciul 23-25, 024053, Bucharest, Romania aut De Batist Marc Renard Centre of Marine Geology (RCMG), University of Ghent, Krijgslaan 281 S8, 9000, Ghent, Belgium aut Gillet Hervé IFREMER Brest, DRO/GM LES, B.P. 70, 29280, Plouzané, France aut Geo-Marine Letters Springer-Verlag 27/2-4(2007-06-01), 173-183 0276-0460 27:2-4<173 2007 27 367 https://doi.org/10.1007/s00367-007-0068-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00367-007-0068-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Popescu Irina Renard Centre of Marine Geology (RCMG), University of Ghent, Krijgslaan 281 S8, 9000, Ghent, Belgium aut NATIONALLICENCE 700 1- Lericolais Gilles IFREMER Brest, DRO/GM LES, B.P. 70, 29280, Plouzané, France aut NATIONALLICENCE 700 1- Panin Nicolae GeoEcoMar Bucharest, Str. D. Onciul 23-25, 024053, Bucharest, Romania aut NATIONALLICENCE 700 1- De Batist Marc Renard Centre of Marine Geology (RCMG), University of Ghent, Krijgslaan 281 S8, 9000, Ghent, Belgium aut NATIONALLICENCE 700 1- Gillet Hervé IFREMER Brest, DRO/GM LES, B.P. 70, 29280, Plouzané, France aut NATIONALLICENCE 773 0- Geo-Marine Letters Springer-Verlag 27/2-4(2007-06-01), 173-183 0276-0460 27:2-4<173 2007 27 367 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer