Isotopic composition of dissolved inorganic carbon in subsurface sediments of gas hydrate-bearing mud volcanoes, Lake Baikal: implications for methane and carbonate origin
Krylov, A. A. ; Khlystov, O. M.; Hachikubo, A.; Minami, H.; Nunokawa, Y.; Shoji, H.; Zemskaya, T. I. ; Naudts, L.; Pogodaeva, T. V. ; Kida, M.; Kalmychkov, G. V. ; Poort, J. (2010). Isotopic composition of dissolved inorganic carbon in subsurface sediments of gas hydrate-bearing mud volcanoes, Lake Baikal: implications for methane and carbonate origin. Geo-Mar. Lett. 30(3-4): 427-437. dx.doi.org/10.1007/s00367-010-0190-2 In: Geo-Marine Letters. Springer: Heidelberg; Berlin. ISSN 0276-0460; e-ISSN 1432-1157, more |  |
| Authors | | Top | - Krylov, A. A.
- Khlystov, O. M.
- Hachikubo, A.
- Minami, H.
| - Nunokawa, Y.
- Shoji, H.
- Zemskaya, T. I.
- Naudts, L., more
| - Pogodaeva, T. V.
- Kida, M.
- Kalmychkov, G. V.
- Poort, J., more
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| Abstract | We report on the isotopic composition of dissolved inorganic carbon (DIC) in pore-water samples recovered by gravity coring from near-bottom sediments at gas hydrate-bearing mud volcanoes/gas flares (Malenky, Peschanka, Peschanka 2, Goloustnoe, and Irkutsk) in the Southern Basin of Lake Baikal. The d13C values of DIC become heavier with increasing subbottom depth, and vary between -9.5 and +21.4‰ PDB. Enrichment of DIC in 13C indicates active methane generation in anaerobic environments near the lake bottom. These data confirm our previous assumption that crystallization of carbonates (siderites) in subsurface sediments is a result of methane generation. Types of methanogenesis (microbial methyl-type fermentation versus CO2-reduction) were revealed by determining the offset of d13C between dissolved CH4 and CO2, and also by using d13C and dD values of dissolved methane present in the pore waters. Results show that both mechanisms are most likely responsible for methane generation at the investigated locations. |
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