The chemical and isotopic compositions of hot springs in the San Marcos region of Guatemala are internally consistent with a hydrologic model in which a deep 240°C reservoir and one or more shallow 195–200°C reservoirs are present. Variations in hot-spring water compositions results from a combination of boiling, mixing with cold, dilute water, and chemical re-equilibration with decreasing temperature. The recharge water for the deep 240°C reservoir is isotopically heavier than the local meteoric water and probably comes from many kilometers to the west or southwest. The water in the shallow reservoir is a mixture of the 240°C water with about 20 ± 5% of cold, locally derived meteoric water. After mixing, the water in the shallow reservoir re-equilibrates with reservoir rock at 195–200°C. In some places additional mixing with cold water occurs after water leaves the shallow reservoir.
|Title||Geochemical evaluation of the geothermal resources in the San Marcos region, Guatemala|
|Authors||R.O. Fournier, B.B. Hanshaw|
|Publication Subtype||Journal Article|
|Series Title||Applied Geochemistry|
|Record Source||USGS Publications Warehouse|