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AGU: Geophysical Research Letters

 

Keywords

  • gas hydrate
  • Lake Baikal
  • stable isotope

Index Terms

  • Marine Geology and Geophysics: Gas and hydrate systems
  • Geochemistry: Stable isotope geochemistry
  • Biogeosciences: Isotopic composition and chemistry

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L18504, 5 PP., 2009
doi:10.1029/2009GL039805

Model of formation of double structure gas hydrates in Lake Baikal based on isotopic data

Akihiro Hachikubo

Kitami Institute of Technology, Kitami, Japan

Oleg Khlystov

Limnological Institute, SB RAS, Irkutsk, Russia

Andrey Manakov

Nikolaev Institute of Inorganic Chemistry, SB RAS, Novosibirsk, Russia

Masato Kida

Kitami Institute of Technology, Kitami, Japan

Advanced Industrial Science and Technology, Sapporo, Japan

Alexey Krylov

All-Russian Research Institute for Geology and Mineral Resources of the World Ocean, Russian Academy of Sciences, St. Petersburg, Russia

Hirotoshi Sakagami

Kitami Institute of Technology, Kitami, Japan

Hirotsugu Minami

Kitami Institute of Technology, Kitami, Japan

Nobuo Takahashi

Kitami Institute of Technology, Kitami, Japan

Hitoshi Shoji

Kitami Institute of Technology, Kitami, Japan

Gennadiy Kalmychkov

Vinogradov Institute of Geochemistry, SB RAS, Irkutsk, Russia

Jeffrey Poort

Renard Centre of Marine Geology, Ghent University, Ghent, Belgium

We measured the isotopic compositions of methane (C1) and ethane (C2) of hydrate-bound gas and of dissolved gas in pore water retrieved from bottom sediments in Lake Baikal. Both structure I (sI:3%C2) and II (sII:14%C2) gas hydrates are observed in the same sediment cores in Kukuy K-2 mud volcano. We found that C2 δD of sI gas hydrate is larger than that of sII, whereas C1 δ 13C, C1 δD and C2 δ 13C values are practically the same in both hydrate structures. δ 13C of C1 and C2 of hydrate-bound gas are several permil smaller than those in pore water, showing that the current pore water is not the source of gas hydrates. These findings lead to a new model where the sII gas hydrates were formed prior to the sI hydrates.

Received 28 June 2009; accepted 14 August 2009; published 24 September 2009.

Citation: Hachikubo, A., et al. (2009), Model of formation of double structure gas hydrates in Lake Baikal based on isotopic data, Geophys. Res. Lett., 36, L18504, doi:10.1029/2009GL039805.

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