Japan Geoscience Union Meeting 2014

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Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS22_29PM1] Gas hydrates in environmental-resource sciences

Tue. Apr 29, 2014 2:15 PM - 4:00 PM 213 (2F)

Convener:*Hitoshi Tomaru(Department of Earth Sciences, Chiba University), Akihiro Hachikubo(Environmental and Energy Resources Research Center, Kitami Institute of Technology), Sumito Morita(Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology), Chair:Akihiro Hachikubo(Environmental and Energy Resources Research Center, Kitami Institute of Technology), Hitoshi Tomaru(Department of Earth Sciences, Chiba University)

3:30 PM - 3:45 PM

[MIS22-06] Quantify methane seeping flux from Ashizuri knoll, Nankai Trough

*Shuichi HARA1, Urumu TSUNOGAI1, Daisuke KOMATSU1, Juichiro ASHI2, Ko-ichi NAKAMURA3, Michinari SUNAMURA4, Fumiko NAKAGAWA5, Tomohiro TOKI6 (1.Graduate School of Environmental Studies, Nagoya Univ., 2.ORI.,Tokyo Univ., 3.National Institute of Advanced Industrial Science and Technology, 4.Division of Earth and Planetary Sciences, Grad. School Sci., Tokyo Univ., 5.Division of Earth and Planetary Sciences, Grad. School Sci.Hokkaido Univ,., 6.Department of chemistry, Bioligy and Marine Science,Ryukyu Univ,.)

The Ashizuri Knoll is located on the southern margin of Tosa Basin (ca. 1000 m depth) in the western Pacific Ocean. The top of the knoll is 534 m depth.The BSR have been detected around the knoll. Beside, seepage methane bubbles were found at top of the knoll. Extensive geochemical surveys on the water column around Ashizuri Knoll were done in September, 2013.The primary purpose of the study was to quantify the seeping flux of methane from the knoll by measuring the spatial distribution of methane around the knoll. Besides, we akso tried to clarify the origin of methane by determining both δ13C and δD values. Enrichment of thermogenic methane up to 145 nmol/L was detected just above the top of knoll. Besides, the methane enriched plume spread northeastward of the knoll at the water depth of 450- 660 m. The calculated methane flux was almost the same with that of off Joetsu hydrate area.