Characteristics of hydrate-bound gas retrieved at the Kedr mud volcano (southern Lake Baikal)

Akihiro Hachikubo, Hirotsugu Minami, Satoshi Yamashita, Andrey Khabuev, Alexey Krylov, Gennadiy Kalmychkov, Jeffrey Poort, Marc De Batist, Alexandr Chenskiy, Andrey Manakov, Oleg Khlystov

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8 Scopus citations

Abstract

We reported the characteristics of hydrate-bound hydrocarbons in lake-bottom sediments at the Kedr mud volcano in Lake Baikal. Twenty hydrate-bearing sediment cores were retrieved, and methane-stable isotopes of hydrate-bound gases (δ13C and δ2H of − 47.8‰ to − 44.0‰ V-PDB and − 280.5‰ to − 272.8‰ V-SMOW, respectively) indicated their thermogenic origin accompanied with secondary microbial methane. Powder X-ray diffraction patterns of the crystals and molecular composition of the hydrate-bound gases suggested that structure II crystals showed a high concentration of ethane (around 14% of hydrate-bound hydrocarbons), whereas structure I crystals showed a relatively low concentration of ethane (2–5% of hydrate-bound hydrocarbons). These different crystallographic structures comprised complicated layers in the sub-lacustrine sediment, suggesting that the gas hydrates partly dissociate, concentrate ethane and form structure II crystals. We concluded that a high concentration of thermogenic ethane primarily controls the crystallographic structure of gas hydrates and that propane, iso-butane (2-methylpropane) and neopentane (2,2-dimethylpropane) are encaged into crystals in the re-crystallisation process.

Original languageEnglish
Article number14747
JournalScientific Reports
Volume10
Issue number1
DOIs
StatePublished - 1 Dec 2020

Scopus subject areas

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