Chemical and Sulfur Isotope Variations in a Thermal Spring System Sampled Through Time

Abstract

Major cations and anions, temperatures and sulfur isotopes of aqueous sulfates and sulfides have been monitored in a Basin and Range thermal spring system for over one year. The data indicate that significant changes in the chemistry are cyclical. Enrichments in Na, Ca, SiO2, C1 and SO4 are accompanied by sympathetic increase in surface temperatures and flow rates suggesting that mixing is the major process controlling the cyclic nature of these various parameters. In site of these chemical variations, major cation ratios remain remarkably constant assuring the applicability of cation geothermometers regardless of the time of year. Major inflow of diluting groundwaters occurs on a regular basis every two to six months.