Introduction: Geothermal Country Overview, Argentina

Argentina is known for its great soccer team and infamous soccer players as well as its large metallic mineral deposits. It is also part of the ‘lithium triangle’ that holds more than 75% of the world’s lithium. Argentina one of the most metal-rich areas in the world due to its location along the Andes mountains. These mineral resources are often related to geothermal (hydrothermal) activity, abundant across the country.

Geology and Geothermal areas of interest

Argentina is divided into four major regions: the Andes, the North, the Pampas, and Patagonia. The Andean region stretches along the western edge of the country from Bolivia to southern Patagonia, forming most of the boundary with Chile.  High enthalpy geothermal resources are mainly found in areas of active volcanism of the southern part of the Central and of the Southern Volcanic Zones of the Andes (Figure 1). Low and medium-enthalpy resources are found in the central and eastern parts of the country. The best known high-temperature geothermal areas in Argentina are Copahue, Domuyo, and Tuzgle.

Figure 1: Geothermal areas of Argentina (from Lahsen et al, 2015)

Copahue geothermal area:

The Copahue volcano is in a complex tectonic setting at the western border of Argentina with Chile, in the Province of Neuquén.  The Copahue geothermal field, located in the northeastern flank of the volcano, associated with the Copahue-Caviahue valley in the Andes with altitudes of 1600 – 2900 meters.  The main fault system is oriented to the NW and associated systems are oriented NE, EW, and NW.

This area is known for its thermal springs. Most popular ones include the Termas de Copahue, Las Máquinas, Las Maquinitas, El Anfiteatro, Crater Lagoon, Volcano Water Spring. Some of them are used for balneotherapy, with facilities for this purpose at Termas de Copahue and Las Máquinas.

Exploration of this geothermal area was carried out between 1974 – 1991. This included geological, geochemical, and geophysical studies along with the drilling of three exploration wells (Table 1) and production tests.  Geophysics (with vertical electrical soundings-VES). This indicates a 230-250°C vapor-dominated system.  Based on the well COP-3, it was estimated that the well could produce about 60 t/h of steam. The geothermal reservoir is in calc-alkaline lavas and pyroclastic rocks of Las Mellizas Formation.

Table 1: Exploration wells in the Copahue geothermal area, Argentina. (From various sources)

Domuyo geothermal area

This area is related to the Domuyo Volcanic Complex in the NW Neuquén Province. The Domuyo volcano (Cerro Domuyo), is part of the “La Cruzada” high (anticline), a significant structural feature in the area. The field is in SW of the Domuyo volcano with the main faults being the E-W oriented Covunco and Manchana-Covunco normal faults. Geothermal manifestations in the area include fumaroles, boiling hot springs, and geysers. In 2003, there were two hydrothermal explosions producing a vapor plume with a maximum height of about 300 m. Key thermal manifestations include the El Humazo and Los Tachos, La Olleta, Aguas Calientes, Los Baños, Las Papas, La Bramadora manifestations.

Geothermal exploration began around 1983 consisting of geological, geochemical studies, drilling of shallow boreholes for heat flow studies, electrical and seismic surveys, Bouguer anomaly, and isotope analyses of thermal waters. Eleven 100 m deep temperature gradient holes were drilled in the study area; fluids, cuttings, and cores were collected. Seven of the wells had bottom hole temperatures above 30°C and three exceeded 50°C.

The geothermal system is divided into eastern and western zones using geochemistry (Table 2) and other studies. The east has three parts

• A small area of vapor-dominated with fumarolic gas
• A transitional zone with water vapor mixed type with a geochemical temperature over 200 °C
• Water dominated

In the western zone, the system is vapor dominated with active fumaroles to water dominated type with temperature below 200 °C.

Table 2: Geofluid type and temperatures of some geothermal manifestations in the Domuyo geothermal area, Argentina. Note temperature is estimated from geothermometry. (from various sources)

The geothermal reservoir is inferred to be at about 700 to 800 m depth in poly-deformed rocks of Choiyoi Group, Plutonitas Varvarco and part of the sedimentary sequence of Neuquen basin.

Cerro Tuzgle- Tocomar geothermal area

This area is in the Puna Plateau in the Jujuy Province and is associated with the NW–SE Calama–Olacapato–Toro (COT) lineament, a regional structure in the Central Andes. Numerous geothermal manifestations are identified including hot springs and sinters-travertine deposits associated with the COT.

Geothermal exploration was undertaken in the 1970’s, 1980’s and 1990’s including volcanology, geochemistry, geophysics (vertical electric soundings, magnetotelluric and gravimetric), and thermal gradient drilling. The results of geochemical studies (water) are listed in Table 3 estimating temperatures between 86 – 235 °C based on several geothermometers.  Geofluid compositions vary from alkaline chloride, sodium chloride bicarbonate, and sodium chloride.

The sedimentary-pyroclastic cover would act as a cap rock (Pastos Chicos Formation). A shallow reservoir 100 to 600 m thick at 50 to 300m depth, identified using geophysical studies.  The magnetotelluric and gravimetric surveys supported the presence of the Cerro Tuzgle magma chamber, with its top below 8 km depth.

Table 3: Geochemical results from the Cerro Tuzgle- Tocomar geothermal area

Valley Del Cura geothermal area

Argentine Frontal Cordillera over the Pampean flat-slab segment. The valley develops within an N-S thrust system in the high Andes of San Juan Province and seven active geothermal zones have been identified. The zones are restricted by two main structural features, the Zancarrón and La Brea ridges. Geochemical studies of these zones estimated temperatures of 180–200 °C. Three of these zones have been studied so far, Los Despoblados and Bañitos-Gollete geothermal area.

Los Despoblados: The area has been studied using geophysical (magnetotelluric) techniques and thermal gradient drilling. Surveys defined two conductive anomalies, one directly linked with the hot springs and the other one without superficial manifestation. Both anomalies show structural control and deep circulation of geothermal fluids. Eight thermal gradient drills were drilled (250 m) at the Los Despoblados geothermal area.

Bañitos-Gollete: Salt deposition is a key characteristic of geothermal manifestations in this area along with 35 – 60°C thermal springs with vigorous gas flux, seasonal cold springs, and mud pools. The waters are classified as sodium-chloride and sodium-bicarbonate. Geothermometric studies estimated reservoir temperatures of 130 – 150°C. Preliminary geophysical studies (audiomagnetotellurics) has been carried out confirming that the N-S fault system controls the flow path and that a conductive heat-driven system fits the geologic setting, dominated by a deep circulation over a roughly low geothermal gradient.

Low temperature

These resources are in the volcanic-sedimentary basin hosted in an inter-cratonic region of -normal to high geothermal gradient. The Tacorralo – Rio Hondo and Bahia Blanca – Pedro Luro thermal systems have temperatures between 75 – 85 °C at depths from 300 m – 800 m.  Sedimentary geothermal systems with normal geothermal gradients include Chacoparanense, Rosario, El Salado, Laboulaye, Macachin, Niriguau, San Jorge, and Magallanes.

Status and future

The Copahue is the most advanced high-temperature project in Argentina. In 1988 a binary-cycle pilot plant was installed on the COP-1 site, with a capacity of 0.67 MWe. The binary prototype unit was in operation until 1996.

In 1997-98, Neuquén Province implemented a district heating project in the village of Copahue, using geothermal vapor to heat the streets and buildings.

As of December 2019, the installed geothermal direction use capacity sits at 204 MWt and the major activities include direct heating, greenhouse, balneology, snow melting, aquaculture.

This wraps up another Geothermal Country Overview, featuring Argentina.  We hope you scroll throughout blog and read others to better understand the global geothermal market, its potential, and the future of clean energy.

We encourage you to Follow, Like, and Share our content on social media to expand the awareness of geothermal.

A special thank you to our Guest Author, Jason Fisher.  Jason has been instrumental in building out our Geothermal Country Overviews blog series over the past 2 years.  Check out more of his work throughout our blog and his: Isle of Rocks

Read more Recent Geothermal Country Overviews here:  El Salvador – India – Uganda

References and Further Reading

Arnold, Y.P., Franco, G., Tassi, F., Caffe, P.J., Jofre, C., Claros, M., Ulberich, J.P.V., Rizzo, A.L. and Cabassi, J., 2020. Geochemical features of hydrothermal systems in Jujuy Province, Argentina: Hints for geothermal fluid exploration. Journal of South American Earth Sciences.

Barcelona, H., Favetto, A., Peri, G., Pomposiello, C. & Ostera, H., 2014. Geothermal system of Despoblados by magnetotelluric data, Valle del Cura, San Juan. Revista de la Asociacion Geologica Argentina, 71(4).

Barcelona, H., Favetto, A., Peri, V.G., Pomposiello, C. and Ungarelli, C., 2013. The potential of audiomagnetotellurics in the study of geothermal fields: a case study from the northern segment of the La Candelaria Range, Northwestern Argentina. Journal of Applied Geophysics, 88.

Barcelona, H., Lelli, M., Norelli, F., Peri, G. and Winocur, D., 2019. Hydrochemical and geological model of the Bañitos-Gollete geothermal system in Valle del Cura, main Andes Cordillera of San Juan, Argentina. Journal of South American Earth Sciences, 96.

Barcelona, H., Peri, G., Wincour, D. and Favetto, A., 2019. Audiomagnetotelluric survey at the Bañitos-Gollete geothermal area, main Andes Cordillera of San Juan, Argentina. Geologica acta, 17.

Barcelona, H., Yagupsky, D. and Agusto, M., 2019. The layered model of the Copahue geothermal reservoir, Argentina. Geothermal Energy, 7(1).

Galetto, A., García, V. and Caselli, A., 2018. Structural controls of the Domuyo geothermal field, Southern Andes (36° 38′ S), Argentina. Journal of Structural Geology, 114.

Giordano, G., Pinton, A., Cianfarra, P., Baez, W., Chiodi, A., Viramonte, J., Norini, G. and Groppelli, G., 2013. Structural control on geothermal circulation in the Cerro Tuzgle–Tocomar geothermal volcanic area (Puna plateau, Argentina). Journal of Volcanology and Geothermal Research, 249.

Lahsen, A., Rojas, J., Morata, D. and Aravena, D., 2015. Exploration for high-temperature geothermal resources in the Andean countries of South America. In Proceedings of the world geothermal congress, Melbourne, Australia.

Mas, G.R., Bengochea, L. and Mas, L.C., 2005. Thermometric study of Copahue geothermal field; Argentina. In Proceedings World geothermal congress, Antalya, Turkey.

Mas, L.C., 2005. Present status of the Copahue geothermal project. In World Geothermal Congress. Antalya, Turkey, Turkey.

Mas, L.C., Mas, G.R. and Bengochea, L., 2000, June. Heat flow of Copahue geothermal field, its relation with tectonic scheme. In Proceedings of world geothermal congress, Tohoku, Japan.

Pesce, A.H. and Johanis, P.E., 2000. The geothermal resources of northeastern Argentina. In World Geothermal Congress, Kyushu–Tohoku, Japan, CD Rom.

Pesce, A.H., 2010. The Domuyo Geothermal Area, Neuquén, Argentina. Geothermal Resources Council Transactions, 37, pp.309-314.

Roulleau, E., Pizarro, M., Bravo, F., Muñoz, C., Sanchez, J., de la Cal, F. and Esteban, C., 2015. The geothermal system of Copahue-Caviahue volcanic complex (Argentina): New insights from self-potential, CO2 and temperature measurements, with structural and fluid circulation implications. In Congresso Geologico Chileno La Serena.

Vieira, F. and Hamza, V., 2019. Assessment of Geothermal Resources of South America-A New Look. International Journal of Terrestrial Heat Flow and Applied Geothermics, 2(1).