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Thermal anomalies associated with shallow gas hydrates in the K-2 mud volcano, Lake Baikal |
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| Authors: | Jeffrey Poort Oleg M Khlystov Lieven Naudts Albert D Duchkov Hitoshi Shoji Shin’ya Nishio Marc De Batist Akihiro Hachikubo Masato Kida Hirotsugu Minami Andrey Y Manakov Marina V Kulikova Alexey A Krylov |
| Institution: | 1. Renard Centre of Marine Geology, UGent, Krijgslaan 281 S8, 9000, Gent, Belgium 9. ISTeP, UMR 7193 UPMC-CNRS, Univ. Paris 06, 4, place Jussieu, 75005, Paris, France 2. Limnological Institute, SB RAS, 3, Ulan-Batorskaya St., Irkutsk, 664033, Russia 10. Management Unit of the North Sea Mathematical Models, RBINS, 3de en 23ste Linieregimentsplein, 8400, Oostende, Belgium 3. Trofimuk Institute of Petroleum Geology and Geophysics, SB RAS, 3 Akademika Koptyuga Ave, Novosibirsk, 630090, Russia 4. Kitami Institute of Technology, 165 Koen-cho, Kitami, 090-8507, Japan 6. Shimizu Corporation, 3-4-17 Etchujima, Koto-ku, Tokyo, 135-8530, Japan 5. National Institute of Advanced Industrial Science and Technology, Methane Hydrate Research Center, 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo, 062-8517, Japan 7. Nikolaev Institute of Inorganic Chemistry, SB RAS, 3 Akademika Lavrentieva Ave, Novosibirsk, 630090, Russia 8. I.S. Gramberg All-Russia Research Institute for Geology and Mineral Resources of the World Ocean (VNIIOkeangeologia), 1 Anglyisky Ave, St. Petersburg, 190121, Russia |
| Abstract: | Thermal measurements and hydrate mapping in the vicinity of the K-2 mud volcano in Lake Baikal have revealed a particular type of association of thermal anomalies (29–121?mW?m–2) near hydrate-forming layers. Detailed coring within K-2 showed that hydrates are restricted to two distinct zones at sub-bottom depths exceeding 70–300?cm. Temperature data from stations with hydrate recovery and degassing features all display low thermal gradients. Otherwise, the thermal gradients within the mud volcano are generally increased. These findings imply a more complicated thermal regime than often assumed for mud volcanoes, with important roles for both fluids and hydrates. The coexistence of neighbouring low and high thermal anomalies is interpreted to result from discharging and recharging fluid activity, rather than hydrate thermodynamics. It is suggested that hydrates play a key role in controlling the fluid circulation pattern at an early stage. At a later stage, the inflow of undersaturated lake water would favour the dissolution of structure I hydrates and the formation of structure II hydrates, the latter having been observed on top of structure I hydrates in the K-2 mud volcano. |
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