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Article Dans Une Revue Scientific Reports Année : 2020

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

Résumé

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.

Domaines

Volcanologie
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Dates et versions

hal-02965976 , version 1 (13-10-2020)

Identifiants

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Akihiro Hachikubo, Hirotsugu Minami, Satoshi Yamashita, Andrey Khabuev, Alexey Krylov, et al.. Characteristics of hydrate-bound gas retrieved at the Kedr mud volcano (southern Lake Baikal). Scientific Reports, 2020, 10, pp.14747. ⟨10.1038/s41598-020-71410-2⟩. ⟨hal-02965976⟩
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