Characterization of Alteration Minerals Within a Volcanic Dome of the Paipa Geothermal System, Boyacá, Colombia
Valeria GARCÍA, Elizabeth TORIO, John J. SÁNCHEZ
[UNIVERSIDAD NACIONAL DE COLOMBIA, Colombia]
Several initiatives have been undertaken in Colombia to promote the search for alternative sources of renewable energy, among which is geothermal energy. The main objectives being the reduction of greenhouse gas emissions and to reduce the dependence on fossil fuels. Colombia is one of the South American countries that has important geothermal resources, mainly associated to volcanic areas, such as Nevado del Ruiz, Azufral, and Chiles-Cerro Negro volcanoes, the latter being the focus of the Binational Geothermal Project "Tufiño-Chiles-Cerro Negro" (a joint initiative of Colombia and Ecuador). Additionally, the Eastern Cordillera hosts the Paipa-Iza geothermal area (Boyacá State), considered to be one of the most promising areas. The temperature of the reservoir has estimates of 120°C using quartz geothermometry. However, due to the process of mixing within the system and the presence of a non-thermal brine source, this temperature could be lower than that of the reservoir. A simple enthalpy-silica mixing model indicates a maximum temperature of 230° C. The complexity of the mixing processes presents a challenge in inferring the physical-chemical conditions of the reservoir. As a contribution to a refined model, a hydrothermal alteration study was conducted in one of the volcanic domes of the Paipa geothermal area. The objective being to understand the types of processes based on the relationship of the chemical composition of the rocks with the temperature of the reservoir. Two types of geological analyses were performed: petrography of thin sections and X-ray diffraction. The analyzed rocks were classified as trachyte and quartz-rich trachyte. The primary minerals identified were alkali feldspar, plagioclase, hornblende and quartz. The presence of alkali feldspar possibly influences the formation of halloysite and kaolinite, belonging to argillic alteration.
|        Topic: Exploration||Paper Number: 11131|