Origin of methane-rich natural gas at the West Pacific convergent plate boundary

Sano, Yuji; Kinoshita, Naoya; Kagoshima, Takanori; Takahata, Naoto; Sakata, Susumu; Toki, Tomohiro; Kawagucci, Shinsuke; Waseda, Amane; Lan, Tefang; Wen, Hsinyi; Chen, Ai-Ti; Lee, Hsiaofen; Yang, Tsanyao F.; Zheng, Guodong; Tomonaga, Yama; Roulleau, Emilie; Piniti, Daniele L. (2017). Origin of methane-rich natural gas at the West Pacific convergent plate boundary. Scientific Reports, 7(1), p. 15646. Nature Publishing Group 10.1038/s41598-017-15959-5

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Methane emission from the geosphere is generally characterized by a radiocarbon-free signature and might preserve information on the deep carbon cycle on Earth. Here we report a clear relationship between the origin of methane-rich natural gases and the geodynamic setting of the West Pacific convergent plate boundary. Natural gases in the frontal arc basin (South Kanto gas fields, Northeast Japan) show a typical microbial signature with light carbon isotopes, high CH4/C2H6 and CH4/3He ratios. In the Akita-Niigata region – which corresponds to the slope stretching from the volcanic-arc to the back-arc –a thermogenic signature characterize the gases, with prevalence of heavy carbon isotopes, low CH4/C2H6 and CH4/3He ratios. Natural gases from mud volcanoes in South Taiwan at the collision zone show heavy carbon isotopes, middle CH4/C2H6 ratios and low CH4/3He ratios. On the other hand, those from the Tokara Islands situated on the volcanic front of Southwest Japan show the heaviest carbon isotopes, middle CH4/C2H6 ratios and the lowest CH4/3He ratios. The observed geochemical signatures of natural gases are clearly explained by a mixing of microbial, thermogenic and abiotic methane. An increasing contribution of abiotic methane towards more tectonically active regions of the plate boundary is suggested.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Rock-Water Interaction

UniBE Contributor:

Tomonaga, Yama

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

2045-2322

Publisher:

Nature Publishing Group

Funders:

Organisations 15 not found.
Organisations 17 not found.

Language:

English

Submitter:

Yama Tomonaga

Date Deposited:

12 Dec 2017 14:10

Last Modified:

25 Oct 2019 07:08

Publisher DOI:

10.1038/s41598-017-15959-5

PubMed ID:

29142325

BORIS DOI:

10.7892/boris.107171

URI:

https://boris.unibe.ch/id/eprint/107171

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