Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Evening Poster

S (Solid Earth Sciences) » S-CG Complex & General

[S-CG62] Crustal fluids and deformation

Wed. May 23, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Naoji Koizumi(School of Environmental Science,the University of Shiga Prefecture), Koji Umeda(Hirosaki University), Norio Matsumoto(産業技術総合研究所地質調査総合センター地震地下水研究グループ, 共同), Hidemi Tanaka(School of Science, The University of Tokyo)

[SCG62-P06] Geochemistry of hot-spring waters in the Shimokita peninsula

Urara Takashima1, *Koji Umeda1 (1.Hirosaki University)

Water and gas samples from 9 hot springs in the Shimokita Peninsula, northeast Japan, were collected for chemical and isotopic analyses. Anion composition suggests that the hot spring waters of the area are classified into 5 types (Cl, Cl-SO4, Cl-HCO3, SO4, HCO3 types). The 3He/4He ratios near the volcanic front and associated with the back-arc side of subduction zones are about four times higher than the atmospheric ratio, whereas those in the fore-arc region are significantly lower than the relative to atmospheric value. The distinctive Br/Cl and I/Cl ratios suggest that the hot spring waters collected in the fore-arc region result from the mixing of sea water and diagenetic dehydrated fluid.