Geochemistry of the Puchuldiza and Tuja hot springs, Chile

Chemical analyses of the waters discharged from 35 hot springs in the Puchuldiza-Tuja geothermal area in northern Chile are listed. Water compositions over an area of 25-30 sq. km were constant, suggesting that surface activity was supplied from a common reservoir, and/or the deep hot waters were associated with the same rock type. There was evidence that the aquifer rock was andesite. Variations in the concentrations of constituents in the springs appeared to result from shallow dilution and evaporation of the rising and surface hot waters respectively. Chemical geothermometry suggested a temperature of between 180 and 210 deg. C for the deep water, the temperature at Puchuldiza being possibly slightly higher than at Tuja. The natural heat flow from the Puchuldiza-Tuja area, estimated from the chloride outputs of springs, was approximately 7900 kcal/s (33 MW) (auth)