The chemistry of spring waters and fumarolic gases encircling Santa María volcano, Guatemala: Insights into regional hydrothermal activity and implications for volcano monitoring

Abstract

Springs encircling Santa María volcano in Guatemala generally contain bicarbonate waters. Bicarbonate waters southwest of the persistently active Santiaguito lava dome are characterized by high Mg/Ca. Other springs contain acid sulfate or chloride waters. Most acid sulfate and chloride waters are spatially confined to springs, wells, and streams of the Zunil and Zunil-II (Sulfur Mountain) geothermal fields on the flanks of the Cerro Quemado dome complex, 5 km to the east-northeast of Santa María. Some acid sulfate waters have unusually high S/Cl ratios (20–70). Chloride waters are dilute versions of typical geothermal brines. The δ13C ratios of all...