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Title | : | Origin of methane-rich natural gas at the West Pacific convergent plate boundary |
Authors | : | 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 Pinti, Daniele L. |
Issue Date | : | 15-Nov-2017 |
Abstract | : | 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. |
URL | : | https://doi.org/10.1016/j.bbrc.2016.12.03610.1038/s41598-017-15959-5 |
Type Local | : | 雑誌掲載論文 |
ISSN | : | 2045-2322 |
Publisher | : | Nature Publishing Group |
URI | : | http://hdl.handle.net/20.500.12000/37627 |
Citation | : | Scientific Reports Vol.7 |
Appears in Collections | : | Peer-reviewed Journal Articles (Faculty of Science)
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