Shallow gas hydrates off southwest Taiwan and their mechanisms

Yin Sheng Huang, Shu Kun Hsu, Chih Chieh Su, Andrew Tien Shun Lin, Pai Sen Yu, Nathalie Babonneau, Gueorgui Ratzov, Serge Lallemand, Pi Chuen Huang, Shiao Shan Lin, Jing Yi Lin, Kuo Yen Wei, Yuan Pin Chang, Neng Ti Yu, Ching Hui Tsai

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

We have collected two shallow gas hydrate samples at two sites having different geological settings off southwest Taiwan during the cruise MD214 in 2018. The first core site, MD18-3542, is on the South Yuan-An East Ridge at ~ 1200 m water deep, where a structural unconformity covered by fine-silt sediments appears at ~ 5.5 m below the seafloor. The second core site, MD18-3543, is close to the Good-Weather Ridge at ~ 1100 m water deep, where a gas-related pockmark structure and authigenic carbonates are present at shallow strata with fine-silt sediments near the seafloor. Sediment properties of core MD18-3542 are distinctively different above and below the layer corresponding to the unconformity. Both cores show obvious gaps or voids in the lower core halves. The core features could be linked to the dissociated methane upward migrating from deep strata. Core site settings with upwelling methane would favor the formation of shallow gas hydrates. At site MD18-3542, the shallow hydrate could be formed due to high concentration methane kept beneath the unconformity covered by fine-silt sediments. At site MD18-3543, the shallow hydrate could be formed due to an extremely high flux of upwelling methane trapped either beneath the authigenic carbonates or fine-silt sediments.

Original languageEnglish
Article number7
JournalMarine Geophysical Research
Volume42
Issue number1
DOIs
StatePublished - Mar 2021

Keywords

  • Hydrate dissociation
  • MD core
  • Off SW Taiwan
  • Shallow gas hydrate

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