Geochemistry of Rajapur and Puttur Thermal Springs of the West Coast, India

Abstract Thennal springs of Rajapur and Puttur (Irde and Banduru) are of low-temperature and low-flow type. Though they are located at two different geological set up, they fall in Na-HCO3 facies . The imprints of basalt - thermal water interaction at Rajapur and local equilibration of doleritic dyke with the thermal water of Irde is deduced. The reservoir of the Rajapur thermal spring is likely to be located in the Precambrian formations, as that of Puttur thermal springs and hence the chemical processes undergoing in these systems are similar. The reservoir temperatures estimated using chemical geothermometers are about 200°C and >120°C for the Puttur and Rajapur thermal springs respectively. Illite, K-mica. chlorite. kaolinite. Ca-montmorillonite and philipsite are the expected secondary minerals in the system.