Hydrogeochemical Exploration of the Tecuamburro Volcano Region, Guatemala

Abstract

Approximately 100 thermal and nonthermal waters samples and 20 gas samples from springs and fumaroles have been chemically and isotopically analyzed to help evaluate the geothermal potential of the Tecuamburro Volcano region, Guatemala. Thermal waters of the acid sulfate, steam condensate, and neutral chloride types generally occur in restricted hydrogeologic areas: Tecuamburro Laguna Ixpaco (acid sulfate); andesite highland north of Tecuamburro (steam condensate); Rio Los Escalavor (neutral chloride). One small area of neutral chloride springs east of the village of Los Esclabos has no relation to the Tecuamburro geothermal system. Neutral chloride springs on the Rio Los Esclavos east and southeast of Tecuamburro show mixing with various types of groundwater's and display a maximum oxygen 18 enrichment compared to the world meteoric line of only about 1.5%. Maximum estimated subsurface temperatures from liquid geochemistry are <200°C. In contrast, maximum estimated subsurface temperatures based on gas compositions in the Laguna Ixpaco area are about 300°C. The relation of neutral chloride waters to the overall Tecuamburro geothermal system is no entirely resolved but we have suggested two system models. Regardless of model, we believe that a first exploration drill hole should be sited within 0.5 km of Laguna Ixpaco to tap the main geothermal reservoir or its adjacent main up flow zone.