Chemistry of Geothermal Waters

Abstract

At least 95 percent of hot spring waters is meteoric, precipitation from rain and snow, and originally free of mineral content. Any remainder could be magmatic. The substantial quantities of chemicals they carry when they reappear at the surface are picked up during their circuitous subterranean passages. The extreme diversity in the composition of hot spring waters results principally from chemical reactions with the particular rock minerals through which they pass, with dissolved gases, and with atmospheric gases present. Further, mixing and diluting with cold, shallow, less mineralized meteoric water or those with different dissolved components as well as the boiling off of water affect their composition. Geochemical analyses lead to somewhat ambiguous conclusions although the bulk of the evidence points to rather extensive mixing in most cases.