Hydrochemical records on long-term changes of deep groundwater system, Japan

Iwatsuki, Teruki  ; Mizuno, Takashi   ; Hama, Katsuhiro ; Kunimaru, Takanori

This study aims to develop the methodology for the evaluation of long-term stability of groundwater systems. To this aim, crystal morphology, chemical and isotopic property of carbonate minerals are examined to estimate the past hydrogeological condition in different groundwater systems in the crystalline rock at Tono area and sedimentary rock at Horonobe area, Japan. The results show that detail analysis of multilayered mineralization associated with groundwater flow paths provides available information to evaluate long-term palaeohydrogeological changes of groundwater system in crystalline rock. On the other hand, it is inconclusive regarding the feasibility of such method for sedimentary rock.