Origins of hot spring water around Tsugaru area from dissolved major cation and anion analyses

Abstract

We have collected hot spring water samples from the Tsugaru area of Aomori prefecture. The major inorganic components were analyzed and the results were plotted on the trilinear diagrams. A group, showing low pH, influenced by volcanic gases, were clearly identified by the plots are on the borders of the anion triangle and the key diagram. Most popular types of hot springs have an end member chemistry of so called fossil seawater, of which magnesium sulfate has been removed under high temperature and pressure and magnesium exchanged by sodium and potassium from underground water. Another end member chemistry is suggested as a ground water having high concentrations of calcium, sodium, and potassium carbonates. Major hot springs of the rest are explained as mixings of meteorological water having present sea water ionic ratio and various ground waters. These ground waters must have quite variable concentration ratios of alkali and alkaline earth elements. We are investigating the relationship of the chemistry and the location with geological settings.