Massive gas hydrates buried on Umitaka Spur in the Sea of Japan: description, origin, and significance to methane cycling in marine sediment

Hiruta, Akihiro; Matsumoto, Ryo

doi:10.1007/s00367-022-00735-w

Cited by 4 publications

(9 citation statements)

References 39 publications

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“…Most gas hydrate samples were analyzed using X-ray computed tomography before Raman analysis . For computed tomography, gas hydrate samples were removed from liquid N 2 for approximately 20 min and returned to liquid N 2 storage for future studies including Raman analysis.…”

Section: Methodsmentioning

confidence: 99%

“…Raw data after wavenumber calibration are available in Hiruta. 66,67 The cage occupancy ratio (θ LC /θ SC ) of CH 4 was calculated from the ratio of the integrated intensity of the two C−H vibration bands derived from CH 4 in the LC and SC (cf. Sum et al 68 and Chazallon et al 69 ):…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Gamo and Horibe, Sudo, and Minami et al). The temperature profile of the water column indicates that the upper limit of the CH 4 hydrate stability zone is located approximately 600 m above the seafloor (approximately 320 m below the sea surface) …”

Section: Geological Settingsmentioning

confidence: 99%

“…PC1701, PC1804, and PC1806 indicate locations of piston coring where near-seafloor gas hydrates were recovered. This figure was reproduced with permission from ref . Copyright 2022 Springer Nature.…”

Section: Geological Settingsmentioning

confidence: 99%

“…The Umitaka Spur in the Sea of Japan is anomalously enriched in massive gas hydrates, some of which are distributed at sediment depths greater than 30 mbsf. , Sedimentation of massive gas hydrates originally developed at shallower sediment depths has been proposed as the most likely scenario for the following reasons: the development of thick fractures corresponding to approximately 1–4 m long columnar samples is unrealistic, and the internal structures of such deep samples exhibit traces of complicated growth processes unlikely to occur in deep-stiffened sediments . In this scenario, deep massive gas hydrates are older than shallow ones when the distribution depth differs by more than 30 m. This is not the case with pore-filling gas hydrates because the pore-filling history is unrelated to sediment depths.…”

Section: Introductionmentioning

confidence: 99%

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Gas Migration through the Crystal Lattice of Gas Hydrates during Sedimentation in Geological Time Scale

Hiruta,

Jin,

Matsumoto

et al. 2024

Energy Fuels

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Massive gas hydrates recovered from various sediment depths at the Umitaka Spur in the Sea of Japan were studied using Raman spectroscopy to determine their burial diagenesis, particularly those initially grown at shallow sediment depths. The samples recovered from sediment depths within 20 m below the seafloor (mbsf) were enriched in H 2 S. These depths were greater than the present sulfate−methane transition (SMT) zone distributed within approximately 1 mbsf of the coring area. The anaerobic oxidation of methane within the SMT is generally the only potential source of high H 2 S at these depths, whereas the deepening of the SMT to approximately 20 mbsf, greater than that of the reference areas, is improbable. A potential scenario for the depth discrepancy is the sedimentation of gas hydrates that originally grew around the near-seafloor SMT. The CH 4 cage occupancy ratio in each sample becomes <1.08 at sediment depths deeper than 40 mbsf. The more homogeneous CH 4 distribution within the gas hydrate at greater depths is attributed to the longer duration of CH 4 migration through the lattice cage of the gas hydrate. The lack of H 2 S in samples at greater depths could also be attributed to the more homogeneous distribution of H 2 S by migration and escape from gas hydrates at H 2 S-depleted environments.

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Section: Methodsmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 99%