Solute fluxes and geothermal potential of Tacaná volcano-hydrothermal system, Mexico–Guatemala

• Published in: Journal of volcanology and geothermal research 2014-11, Vol.288, p.123-131
• Main Authors: Collard, Nathalie, Taran, Yuri, Peiffer, Loïc, Campion, Robin, Jácome Paz, Mariana P.
• Format: Article
• Language: English
• Subjects: Chloride inventory; Chlorides; Coating; Crystalline rocks; Discharge; Earth sciences; Earth, ocean, space; Exact sciences and technology; Flow rate measurements; Fluxes; Geothermal potential; Geothermal resources; Heat output; Hot springs; Igneous and metamorphic rocks petrology, volcanic processes, magmas; Solute flux; Spring (season); Tacaná; Transport
• ISSN: 0377-0273; 1872-6097
• DOI: 10.1016/j.jvolgeores.2014.10.012

Solute and heat fluxes from thermal springs of Tacaná volcano are estimated by the chloride-inventory method. The thermal springs, located at the northwestern slopes of the volcanic edifice, at altitudes from 1500 to 2000m above sea level, discharge water enriched in HCO3 and SO4 (up to 1gkg−1 of each one) with temperatures in the 25–63°C range. There are two distinct groups of springs with a different “chloride-temperature” correlation but with the same 87Sr/86Sr ratio (0.7046±0.0001) indicating the same wall rock composition for different aquifers. Each thermal spring feeds a thermal stream that flows into the main drainage of the area, Río Coatán. The total observed chloride discharge from the thermal springs is estimated as 14.8gs−1 and the total measured heat output of ~9.5MW. Considering a deep fluid temperature of 250°C (calculated using Na–K geothermometer), the corresponding advective heat transport from the deep reservoirs that feed these springs may be estimated as 26MWt. However, the total chloride output measured in the main drainage (Coatán river) is 4 times higher (~59gs−1) than the measured Cl output of thermal springs. This means that other, undiscovered, thermal springs exist in the area and that the natural heat output through thermal springs at Tacaná is significantly higher and depends on the Cl content and temperatures of the unknown thermal water discharges. If chloride concentration in these unknown springs does not exceed 540mgL−1 (the highest analyzed Cl in Tacaná springs) and the discharge temperature is 50°C, then the natural heat output can be estimated at least as 22MWt and the corresponding advective heat transport as ~100MWt. •We estimate the geothermal potential of Tacaná volcano with the chloride inventory method.•The thermal energy release from the springs is estimated at 8.9±1MWt.•The advective heat output from the Tacaná deep reservoir is estimated at 26±3MWt.