First discovery and formation process of authigenic siderite from gas hydrate–bearing mud volcanoes in fresh water: Lake Baikal, eastern Siberia
Krylov, A.; Khlystov, O.; Zemskaya, T.; Minami, H.; Hachikubo, A.; Nunokawa, Y.; Kida, M.; Shoji, H.; Naudts, L.; Poort, J.; Pogodaeva, T. (2008). First discovery and formation process of authigenic siderite from gas hydrate–bearing mud volcanoes in fresh water: Lake Baikal, eastern Siberia. Geophys. Res. Lett. 35(5): 6 pp. dx.doi.org/10.1029/2007GL032917 In: Geophysical Research Letters. American Geophysical Union: Washington. ISSN 0094-8276; e-ISSN 1944-8007, more |  |
| Authors | | Top | - Krylov, A.
- Khlystov, O.
- Zemskaya, T.
- Minami, H.
| - Hachikubo, A.
- Nunokawa, Y.
- Kida, M.
- Shoji, H.
| - Naudts, L., more
- Poort, J., more
- Pogodaeva, T.
|
| Abstract | We report on the first authigenic siderite (FeCO3) concretions recovered from near-bottom sediments at gas hydrate-bearing mud volcanoes in fresh water (Lake Baikal, Eastern Siberia). The carbonates appear as firm ‘plate-type’ formations at the Malenky mud volcano (Southern Baikal Basin) and as soft nodules at the K-2 mud volcano (Central Baikal Basin). Calcium is the main divalent component which substitutes iron in the carbonate lattice (7 to 20 mol%). The d 13C values of the carbonates (+3.3 to +6.8‰ at Malenky, and +16.5 to +21.9‰ PDB at K-2) indicate that their formation is due to methanogenesis. The latter was most likely caused by the microbial methyl-type (acetate) fermentation that is suggested from the isotopic composition of the accompanying methane hydrates and dissolved methane. General depletion of the siderites in 18O (-11.6 to -9.9 ‰ at Malenky, and -13.9 to -12.3‰ PDB at K-2) is mainly inherited from the isotope composition of pore water (-15.2 to -15.4‰ SMOW) at ambient temperature (3.5°C). |
|
