[A-HW25_2AM2] Isotope Hydrology 2014

[AHW25-11] Isotope characteristics of groundwater in and around Mt. Sambe, an active volcano in western Japan

*Masaya YASUHARA¹, Hidekazu SUZUKI², Kazuyoshi ASAI³, Akihiko INAMURA¹, Atsushi YAMAMOTO⁴, Noritoshi MORIKAWA¹, Hiroshi TAKAHASHI¹, Masaaki TAKAHASHI¹, Kohei KAZAHAYA¹, Koichi KITAOKA⁵ (1.Geological Survey of Japan, AIST, 2.Komazawa University, 3.Geo Science Laboratory, 4.Kinki University, 5.Okayama Univeristy of Science)

Keywords:active volcano, groundwater, water chemistry, isotopes, volcanic fluid

A study using a coupled hydrological and geochemical (water chemistry, δD●δ¹⁸O, δ¹³C, and helium isotope) approach is in progress to elucidate the groundwater system in and around Mt. Sambe, a 1126-m high active volcano located in western Japan. Groundwater in its south to east flanks proved to be characterized by high δ¹³C values (in the range between -9 - -5‰δ¹³C) as well as an elevated concentration of total carbon compared to those in other flanks. These observations clearly indicate an admixture of magmatic fluid into shallow groundwater of the south to east flanks, being also in accordance with its water chemistry with an increased chloride ion concentration.