The Relationship of Environmental Conditions and Physicochemistry of Thermal Water and the Nature of Their Siliceous Sinter Deposits at El Tatio, Chile

Abstract

Siliceous sinter forms by evaporation and cooling to temperatures less than 100 °C of near-neutral, alkali-chloride silicarich thermal waters. Their importance resides in their capacity to record environmental conditions and their relationship to the presence of a geothermal field at depth. Sinter textures are controlled by environmental and hydrodynamic conditions whereas their initial mineralogy and chemistry is controlled by the chemical composition of thermal waters. For siliceous sinters to form the discharging hot spring water is oversaturated with respect to amorphous silica. Therefore, the extreme climatic conditions and the particular water geochemistry that occurs at El Tatio geothermal field is reflected in the characteristics of the siliceous sinter deposits. Here we present preliminary results of a study undertaken at El Tatio, designed to determine the effects of thermal water geochemistry and of environmental conditions present during the sinter formation process.