@article{oai:u-ryukyu.repo.nii.ac.jp:02008840,
 author = {Sano, Yuji and Kinoshita, Naoya and Kagoshima, Takanori and Takahata, Naoto and Sakata, Susumu and Toki, Tomohiro and Kawagucci, Shinsuke and Waseda, Amane and Lan, Tefang and Wen, Hsinyi and Chen, Ai-Ti and Lee, Hsiaofen and Yang, Tsanyao F. and Zheng, Guodong and Tomonaga, Yama and Roulleau, Emilie and Pinti, Daniele L.},
 journal = {Scientific Reports},
 month = {Nov},
 note = {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., 論文},
 title = {Origin of methane-rich natural gas at the West Pacific convergent plate boundary},
 volume = {7},
 year = {2017}
}