Interpretation of chemical composition of geothermal fluid from the geothermal field of Baransky volcano, Iturup Island, Russia

Abstract

In this study, the chemistry of representative samples of water from the Baransky volcano geothermal field and hot springs and wells from the low-temperature geothermal area in Snaefellsnes, W-Iceland are compared. The thermal fluids were evaluated chemically using a Cl-SO4-HCO3 triangular diagram. The hot spring waters from Baransky volcano are of the steam-heated (SO4) type with a high SO4, Ca and Na content, and samples from the wells are mature waters (Cl rich). The subsurface temperatures of the geothermal reservoirs were estimated by geothermometers and equilibrium calculations using the quartz, Na-K temperatures calculated by WATCH, and the Na-K-Ca temperatures by SOLVEQ. The Na-K and Na-K-Ca geothermometers provided estimated temperatures close to those measured. The quartz and chalcedony temperatures are higher than those measured. The Na-K-Mg triangular diagram was also applied to evaluate the equilibrium of water with reservoir rock. Schoeller diagrams and silica-enthalpy models were used to estimate possible mixing.