Geochemical Interpretation of Thermal Water Samples from Eastern Part of Mt. Sabalan, Nw – Iran

Abstract

There are several thermal springs in the eastern part of Mt. Sabalan with temperatures ranging from 16 to 47°C. The thermal waters from the eastern part of Mt. Sabalan were found to be peripheral and steam heated waters according to Cl-SO4-HCO3 ternary diagram. The Na-K-Mg-Ca diagram shows that all the thermal waters plotted far from the full equilibration curve indicating these waters are probably not fully equilibrated or high degree of mixing with cold groundwater and or re- equilibration. The Na-K-Mg triangular diagram indicates that all of the waters are immature waters with high Mg content and the application of both Na-K and K-Mg geothermometers becomes doubtful. The Mg content in most of the thermal samples is high, ranging between 8.6 -57 mg/kg. The relationship between δD and δ18O shows that the waters are predominantly meteoric as they are in the meteoric trend line. The silica geothermometers provide the most reliable temperatures for this area, with predicted subsurface temperature values ranging from 96 to 147°C. The geochemical studies and field observations suggest that the study area is a low-temperature geothermal system.