Magmatic fluids play a role in the development of active gas chimneys and massive gas hydrates in the Japan Sea

Glen T. Snyder, Yuji Sano, Naoto Takahata, Ryo Matsumoto, Yoshihiro Kakizaki, Hitoshi Tomaru

Research output: Contribution to journalArticle

Abstract

The Earth's marine continental margins hold significant amount of carbon in the form of gas hydrate which can interact dynamically with seawater and the atmosphere and potentially influence global climate. It is generally assumed that degradation of organic matter, through either biogenic or thermogenic processes, is responsible for the majority of the gas hydrate presently found in these deposits. We present stable isotope and noble gas results from gas hydrates in the eastern margin of the Japan Sea and compare them with previously published data regarding gases which are found nearby in deep hydrocarbon wells associated with Early Miocene igneous and sedimentary rocks. Our results show that most of the gases which accumulate in the hydrate can be described as a mixture between a deeply-sourced methane-rich thermogenic/crustal source (TC), a methane-rich admixture of biogenic gases with relatively shallow air-saturated seawater (BASW) and a methane-poor magmatic-mantle source (MM). The presence of hydrate with a mantle 3He/4He signatures indicates that fluids enriched in mantle gases are responsible for the mobilization of thermogenic gas within active Japan Sea chimney structures. The growth of primary hydrate at shallow marine sediment depths is ongoing, as is the cycling of gas to hydrate which is eventually buried and dissociated at the base of the gas hydrate stability zone, leading to large pockmark structures.

Original languageEnglish
Article number119462
JournalChemical Geology
Volume535
DOIs
Publication statusPublished - 5 Mar 2020

Fingerprint

Gas hydrates
Chimneys
gas hydrate
Gases
Hydrates
Fluids
fluid
Methane
gas
methane
Seawater
Igneous rocks
mantle
seawater
pockmark
Noble Gases
Sedimentary rocks
noble gas
Hydrocarbons
mantle source

Keywords

  • Gas hydrate
  • Helium
  • Japan Sea
  • Methane
  • Noble gas
  • Stable isotopes

Cite this

Snyder, Glen T. ; Sano, Yuji ; Takahata, Naoto ; Matsumoto, Ryo ; Kakizaki, Yoshihiro ; Tomaru, Hitoshi. / Magmatic fluids play a role in the development of active gas chimneys and massive gas hydrates in the Japan Sea. In: Chemical Geology. 2020 ; Vol. 535.
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Magmatic fluids play a role in the development of active gas chimneys and massive gas hydrates in the Japan Sea. / Snyder, Glen T.; Sano, Yuji; Takahata, Naoto; Matsumoto, Ryo; Kakizaki, Yoshihiro; Tomaru, Hitoshi.

In: Chemical Geology, Vol. 535, 119462, 05.03.2020.

Research output: Contribution to journalArticle

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AU - Snyder, Glen T.

AU - Sano, Yuji

AU - Takahata, Naoto

AU - Matsumoto, Ryo

AU - Kakizaki, Yoshihiro

AU - Tomaru, Hitoshi

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