Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Evening Poster

H (Human Geosciences) » H-TT Technology & Techniques

[H-TT18] Development and applications of environmental traceability methods

Tue. May 22, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Ichiro Tayasu(Research Institute for Humanity and Nature), Takanori Nakano(Research Institute for Humanity and Nature, Inter-University Research Institute Corporation National Institutes for the Humanities), Keisuke Koba(京都大学生態学研究センター)

[HTT18-P09] Geochemical characteristics of hydrothermal fluids observed along Median Tectonic Line in Mie-Prefecture, Japan.

*Rofiqul Umam1, Masaharu Tanimizu1, Naoto Sugimoto1, Ryo Nakai1, Yasunori Mori2 (1.Kwansei Gakuin University, 2.Mie Prefecture Health and Environmental Research Institute, Japan)

Keywords:Groundwater, Geofluid, Median Tectonic Line, Mass spectrometry, Hot spring

Island arc magmatism is considered to be triggered by the addition of fluids dehydrated from subducting slab. The relationship among volcanism, hydrothermal ore forming, and hot spring in island arc is therefore important to understand distribution of geofluid in the area. We investigated hot spring in Mie-prefecture to estimate their origin. Various types of hot spring are observed in that area, and their origin and characteristics are estimated from dissolved trace element concentrations and their isotope systematics.

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.