Exploration of Villarrica Geothermal System using Geophysical and Geochemical Techniques [Finale Version] (2025)

Geochemical characterization of the geothermal system at Villarrica volcano, Southern Chile; Part 1: Impacts of lithology on the geothermal reservoir

Geothermics, 2018

Besides temperature, mineralogy, residence time and dilution are crucial for assessing water-rock interaction intensity. The geothermal system at the Villarrica-Quetrupillán-Lanín volcanic chain, Southern Chile, is located across a prominent lithological transition from plutonic rocks of the North Patagonian Batholith (NPB) to volcano-sedimentary units. With the goal to investigate the impact of lithology on medium-enthalpy geothermal fluids, 15 hot spring discharges were sampled and analyzed for anthropogenic tracers and isotopic composition and compared to the analyses of 31 reservoir rock analogues. Comparison of strontium isotope signatures between rock analogues and hot spring discharges allow an allocation of associated reservoir rocks. Chlorofluorocarbons quantify the dilution of the geothermal springs by shallow groundwater, ranging from almost CFC-free samples to dilution with modern meteoric water by up to 50 %. Fluids discharging from plutonic rocks have low proportions of dilution with modern waters, while hot springs discharging from the volcanosedimentary rocks have a higher and variable dilution with modern waters. The fractionation of oxygen isotopes of the SO 4-H 2 O system reveals reservoir temperature estimates of 80-100°C in the plutonic sequence matching discharge temperatures. For the springs discharging from volcano-sedimentary units higher reservoir temperatures of 100-140°C are calculated. On basis of the analysis, a conceptual reservoir model can be derived. Fast fluid ascent is indicated along Liquiñe-Ofqui fault system in the NPB by similar discharge and reservoir temperatures and low surficial dilution rates. Large differences in discharge and reservoir temperatures in the Cura-Mallín formation along with a high influx of surficial water may be attributed to a more branched pathway pattern. In conclusion lithology maybe an important factor when coming to the utilisation of geothermal resources.

Geothermal Energy Potential of a Promissory Area in the Central and Eastern Zones of Sonora, Mexico: A Preliminary Geochemical Study

2015

Geothermal energy is an important renewable energy resource in Mexico, and the evaluation of the energy potential of promising geothermal systems has been defined as an important task for defining the future energy portfolio of the country. For achieving such general goal, a preliminary geochemical study for the evaluation of promissory geothermal zones located in the Central and Eastern of Sonora was carried out. Evidence of previous geological and geochemical exploration studies on the Northwestern zone of Mexico have delimitated some promissory low-to-medium temperature geothermal areas, and suggest that these systems are related to the pull-apart basin dynamics of the Gulf of California hydrothermal systems. The present study was specifically focused to characterize the origin of thermal fluids sampled in the Central and Eastern zone of Sonora, to identify water-rock interaction processes, and to develop a preliminary geochemical model. A field survey was carried out for collecting representative geothermal fluid samples. Chemical analysis of major and minor components in these samples indicated the presence of calcium bicarbonate waters in the Central zone, whereas sulphate-sodium waters were typified for the eastern part. Deep equilibrium temperatures were calculated using new and improved solute geothermometers, and the estimated mean temperature was 150°C. A preliminary geochemical modeling of water-rock interaction processes was also performed using the chemical composition of thermal springs at the expected temperature. Mineral assemblages involving minerals such as muscovite, clinochlore, laumontite, prehnite, kaolinite, and albite were found to be in equilibrium with the geothermal fluids. A deep fluid circulation with the presence of a hydrothermal system characterized by low-to-medium temperatures (T<200°C) seems to dominate in this geothermal system. However, a more detailed study requires to be conducted in the future for a better understanding and characterization of these geothermal resources.

Geothermal System Associated with the Sierra Nevada Volcano, Araucanía Region, Chile

2011

The geothermal system associated with the Pleistocene-Holocene Sierra Nevada volcano in the Araucanía Region of Chile has surface manifestations extending from the north-western flank of the volcano to Manzanar and Malalcahuello. Baños del Toro, located on the northwestern flank of the volcano, has numerous fumaroles and acid pools (acid sulfate waters, T=~90°C, pH=2.1, TDS=3080 mg/L); while Aguas de la Vaca, near the base of the volcano, has a bubbling spring (chloride-sulfate waters, T=~60°C, pH=7.0, TDS=950 mg/L). Five shallow (&lt;120m) wells (2 at Manzanar and 3 at Malalcahuello) in the Cautín River Valley discharge alkaline (pH= 9-10) waters with relatively low TDS (130-210mg/L). The main heat source of the geothermal system is apparently the magmatic system of the Sierra Nevada volcano. Liquiñe-Ofqui Fault Zone (LOFZ) that transects the area provides conduits for the flow of the geothermal waters. The geothermal reservoirs are mainly hosted in the volcanic rocks interbedded w...

Fluid geochemistry of hydrothermal systems in the Arica-Parinacota, Tarapacá and Antofagasta regions (northern Chile)

Journal of Volcanology …, 2010

We investigate the chemical and isotopic composition of water and gas thermal discharges from six hydrothermal systems in the Tarapacà and Antofagasta regions (northern Chile): Surire, Puchuldiza-Tuja, Pampa Lirima, Pampa Apacheta, El Tatio and Torta de Tocorpuri, to determine the chemical-physical conditions at the fluid source. The chemical facies of the thermal discharges vary from Na + -Cl − (El Tatio, Puchuldiza-Tuja and part of Surire where SO 4 2− -rich waters also occur) to Na

Geological and Tectonic Settings Preventing High-Temperature Geothermal Reservoir Development at Mt. Villarrica (Southern Volcanic Zone): Clay Mineralogy and Sulfate-Isotope Geothermometry

In the vicinity of the volcano Villarrica (South-Central Chile), geothermal manifestations at the surface are evident revealing lowenthalpy geothermal processes in the subsurface. The structural geology of the area, postulated by (Sanchez et al., 2013), set up a first draft of a structural model but also naming the complexity of the structural geology in the area generated by the interaction of two major fault systems and a change in the basement geology. In the first phase of the actual research project, geochemical methods are used to characterize the geothermal system. Besides standard geochemical techniques, clay mineralogy and δ 18 O [SO4] /δ 18 O [H2O] isotopes are used to determine the characteristics of the geothermal reservoir. The results of these techniques, pointing at a low-enthalpy reservoir in the vicinity of the active Villarrica volcano, are discussed in context of the special tectonic characteristics in the investigation area.

Preliminary conceptual model of the Cerro Blanco caldera-hosted geothermal system (Southern Puna, Argentina): Inferences from geochemical investigations

Journal of South American Earth Sciences, 2019

The Cerro Blanco Caldera (CBC) is the youngest collapse caldera system in the Southern Central Andes (Southern Puna, Argentina). The CBC is subsiding with at an average velocity of 0.87 cm/year and hosts an active geothermal system. A geochemical characterization of emitted fluids was carried out based on the chemical and isotopic compositions of fumaroles, and thermal and cold springs discharged in this volcanic area with the aim of constructing the first hydrogeochemical conceptual model and preliminary estimate the geothermal potential. The main hydrothermal reservoir, likely hosted within the pre-caldera basement rocks, has a Na +-Clˉ(HCO 3)c omposition with estimated temperatures ≥135°C. The unconsolidated, fine-grained Cerro Blanco ignimbrite likely acts as the cap-rock of the hydrothermal system. The presence of phreatic eruption breccias in the surrounding area of the geothermal fumaroles supports the effectiveness of the pyroclastic deposit as sealing rocks. The isotopic data of water (δ 18 O and δD) indicate a meteoric recharge of the hydrothermal reservoir, suggesting as recharge areas the sectors surrounding the CBC, mainly towards the W and NW where large outcrops of the pre-caldera basement exist. A fault-controlled hydraulic connection between the hot springs and the hydrothermal reservoir is proposed for the Los Hornitos area. The fumaroles show the typical compositional features of hydrothermal fluids, being dominated by water vapor with significant concentrations of H 2 S, CH 4 and H 2. Considering the high geothermal gradient of this area (∼104°C/km) and the relatively high fraction of mantle He (∼39%) calculated on the basis of the measured R/Ra values, the hydrothermal aquifer likely receives inputs of magmatic fluids from the degassing magma chamber. The preliminary geothermal potential at CBC was evaluated with the Volume Method, calculating up to E = 11.4*10 18 J. Both the scarce presence of superficial thermal manifestations and the occurrence of an efficient cap-rock likely contribute to minimize the loss of thermal energy from the reservoir. The results here presented constitute the necessary base of knowledge for further accurate assessment of the geothermal potential and ultimately the implementation of the geothermal resource as a viable energy alternative for small localities or mining facilities isolated from the National Interconnected System due to their remote localization.

La Candelaria Ridge (NW Argentina) as a natural lab for the exploration of the geothermal system of Rosario de La Frontera: methods and preliminary results

Evidence of a new geothermal prospect in the Northern-Central trans-Mexican volcanic belt: Rancho Nuevo, Guanajuato, Mexico

Journal of Iberian Geology, 2021

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The Cachiyacu Geothermal Prospect, Chacana Caldera, Ecuador

b-dig.iie.org.mx

Bernardo Beate(1), Salvatore Inguaggiato(2), Fabian Villares(1), Stalin Benitez(3) and Silvana Hidalgo(4). (1) Dto. de Geologia, Escuela Politecnica Nacional, PO Box 17 01 2759, Quito / Ecuador (2) Istituto Nazionale di Geofisica e Vulcanologia -Palermo, via Ugo La Malfa 1590146, ...

Fluid geochemistry of geothermal systems in northern Chile

sga.conference-services.net

We investigate the chemical and isotopic composition of water and gas thermal discharges from Surire, Puchuldiza-Tuja, Pampa Lirima, Pampa Apacheta, El Tatio and Torta de Tocorpuri geothermal systems, to determine the chemical-physical conditions at the fluid source. The chemical composition of the thermal discharges vary from Na