In this study multivariate statistical analysis are used to characterize relationships between hydrochemical properties of thermal and non-thermal springs. Four factors for thermal waters and two for non-thermal springs were extracted based on factor analysis. In thermal springs, the first factor showed high loading on Ca, Mg, Na and K and this factor was interpreted as leaching of cations in the rocks by meteoric thermal water. The second factor showed high loading on SO4 and it was assumed to be extracted from gypsum dissolution. The third factor showed loading on HCO3 and it was interpreted to be caused by dissolution of limestone. The forth factor showed high loading on SiO2 and it was supposed to be result of alteration of silicate minerals. The δ18O-enrichment with respect to the meteoric water line (MWL), confirms that thermal waters have been diluted by shallow waters with meteoric origin. Comparison of the chemistry of thermal and non-thermal springs and other evidences are indicative of an immature hydrothermal water system in Mahalat. Quartz and Chalcedony geothermometery show the range of 96oC to 131 oC temperature for the Mahalat reservoir.
