2024-03-29T05:20:14Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/448392022-11-17T02:08:08Zhdl_2115_20039hdl_2115_116Discovery of a new hydrothermal venting site in the southernmost Mariana Arc: Al-rich hydrothermal plumes and white smoker activity associated with biogenic methaneGamo, ToshitakaMasuda, HarueYamanaka, ToshiroOkamura, KeiIshibashi, JunichiroNakayama, EiichiroObata, HajimeShitashima, KiminoriNishio, YoshiroHasumoto, HiroshiWatanabe, MasaharuMitsuzawa, KyohikoSeama, NobukazuTsunogai, UrumuKouzuma, FumitakaSano, Yujisubmarine hydrothermal activitysouthern Mariana Troughhydrothermal plume chemistryaluminum anomalybiogenic methane450This paper reports a series of studies leading to the discovery of a submarine hydrothermal field (called Nakayama Field) at an arc seamount (12∞43¢ N, 143∞32¢ E) in the southernmost part of the Mariana Trough, western Pacific Ocean. We first detected hydrothermal plumes characterized by water column anomalies of temperature, light transmission, Mn, Fe, Al, O2, CH4, and d13C of CH4 above the summit caldera of the seamount. Then deep-tow camera surveys confirmed the existence of hydrothermal activity inside the caldera, and an ROV dive finally discovered white smoker-type fluid venting associated with vent fauna. A high concentration of aluminum in the plume and white smoker-type emissions imply acidic hydrothermal activity similar to that observed at the DESMOS Caldera in the eastern Manus Basin, Papua New Guinea. Anomalously low d13C (CH4) of .38‰ of a vent fluid sample compared to other arc hydrothermal systems along the Izu- Bonin and Mariana Arcs suggests an incorporation of biogenic methane based on a subsurface microbial ecosystem.The Geochemical Society of JapanJournal Articleapplication/pdfhttp://hdl.handle.net/2115/44839https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/44839/1/geochemj38p527.pdf0016-70021880-5973AA00654975Geochemical journal3865275342004-04-19engpublisher