[HTT18-P09] Geochemical characteristics of hydrothermal fluids observed along Median Tectonic Line in Mie-Prefecture, Japan.
Keywords:Groundwater, Geofluid, Median Tectonic Line, Mass spectrometry, Hot spring
We investigated the ratios of 11B/10B and 7Li/6Li of hot spring water samples as well as 18O/16O and D/H isotope ratios of water. Resultant 18O/16O-D/H ratios of water were mainly plotted along the fractionation trend of meteoric water and a mixing trend with seawater, but some samples have isotopic shifts toward heavy 18O/16O ratios, which indicate interactions with rocks under high temperature. Their 11B/10B and 7Li/6Li ratios showed very low values for some samples, which suggest that the fluids are originated from deeper part of the earth crust. In addition, a decoupling between the two isotope systems is observed.