A preliminary interpretation of groundwater chemistry in the Horonobe area, Japan

A present study shows a preliminary interpretation of groundwater chemistry based on data obtained from the surface-based investigation phase in the Horonobe URL. The evolution of groundwater in the argillaceous rock could be interpreted as the dilution of fossil seawater, accompanied by diagenetic water-rock interactions. The groundwaters were categorized into three types on the basis of multivariate geostatistical techniques. Results of thermodynamic calculations suggested that the effect on groundwater chemistry by perturbation during sampling. Thus a simple correction method assuming a partial equilibrium with mineral-water interactions was provisionally applied to estimate the in-situ geochemical conditions of groundwater.