Stratigraphic and structural control on the distribution of gas hydrates and active gas seeps on the Posolsky Bank, Lake Baikal |
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Authors: | Lieven Naudts Oleg Khlystov Nick Granin Alexander Chensky Jeffrey Poort Marc De Batist |
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Affiliation: | 1. Renard Centre of Marine Geology (RCMG), Universiteit Gent, Krijgslaan 281s8, 9000, Gent, Belgium 4. Management Unit of the North Sea Mathematical Models (MUMM), Royal Belgian Institute of Natural Sciences (RBINS), 3de en 23ste Linieregimentsplein, 8400, Oostende, Belgium 2. Limnological Institute of the Siberian Division of the Russian Academy of Sciences, P.O. Box 4199, 664033, Irkutsk, Russian Federation 3. Irkutsk State Technical University, 664033, Irkutsk, Russian Federation 5. Institut des Sciences de la Terre de Paris (ISTeP), Université Pierre et Marie Curie (UPMC) Paris VI, case courrier 129, 4 place Jussieu, 75005, Paris, France
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Abstract: | The distribution and origin of shallow gas seeps in the vicinity of the Posolsky Bank in Lake Baikal were studied based on the integration of detailed seismic, multibeam, and hydro-acoustic water-column investigations. In all, 65 acoustic flares have been detected on the Posolsky Fault scarp near the crest of the bank and in a similar, nearby setting at water depths of ?43 to ?332?m. The seismic data reveal BSRs (bottom-simulating reflectors) occurring up to water depths of ?300?m. Calculations involving hydrate stability, heat flow, and topographic modulation based on BSR occurrence and multibeam bathymetry enabled prediction of a methane–ethane gas mixture and heat-flow values that would account for gas hydrate stability in the lake sediments under prevailing ambient conditions. These predictions are supported by ground truth data. The findings suggest that seeps concentrated along the crest of the Posolsky Bank are fed mainly by gas coming from below the base of the gas hydrate stability zone, which would migrate updip via permeable stratigraphic pathways beneath the bank. Gas would ultimately be released into the water column where these pathways are cut off by faults. Figure Conceptual seep model for the Posolsky Bank, Lake Baikal |
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