A Hydrothermally Altered Igneous Intrusion: an Additional Heat Source for the Geothermal System of Paipa, Colombia?

Abstract

The area of Paipa located in the Eastern Cordillera of Colombian Andes, harbor a geothermal system whose main source of heat is associated with the remaining heat of intrusions with ages of the order of 1 MA. To the Northwest of the geothermal area emerges The Durazno, intrusive body characterized by intense hydrothermal alteration and anomalies of radiogenic elements. Hydrothermal alteration is argillic and advanced argillic, suggesting that there was the interaction of the body with fluids pH acid. The anomalies of radiogenic elements were measured in 4 perforations with depths no higher than 100m, in which are reported values of up to 370 ppm of U-238, which would generate a contribution of heat radiogenic maximum to the system of 12.52 uW /m3. This radiogenic heat could heat the surrounding waters, as suggested by the anomalous temperature of 34.8°C in a 97m deep well 3 km from El Durazno. The thermal fluid in the area have a temperature of 75°C and a clear mixture with a salt source, However, in the well near El Durazno, the fluids are sodium bicarbonate and have a temperature of 34°C. These differences could suggest the existence of two different water circuits, where the Durazno would serve as a source of heat to the shallow. It is worth noting that minor concentrations of radiogenic elements to those recorded in the Durazno, they have been considered as sources of heat in the Chena Springs, Alaska area. However, it is required to know the volume and residence time of the water that interacts with El Durazno, As well as the permeability and make water balances to have greater certainty of the radiological heat generated by this body.