Expert-driven play Fairway Analysis applied to the Azufral Volcano Geothermal Area in southwestern Colombia

Abstract

The Azufral Volcano is a polygenetic volcanic structure formed by Pliocene-Pleistocene andesites, and upper Pleistocene-Holocene lava domes and pyroclastic deposits. Warm and hot springs, fumaroles, hydrothermal eruption craters, and hydrothermal alteration zones are identified at Azufral Volcano and its surroundings. The area around Azufral Volcano has been affected by two potentially active fault systems (striking SW-NE and NW-SE) and shallow (< 21 km depth), low magnitude seismicity (< M3.3). For this study, an expert-driven Play Fairway Analysis at the Azufral Volcano Geothermal Area was conducted (∼ 520 km2). This Play Fairway Analysis was performed using existing data collected by the Colombian Geological Survey (Servicio Geológico Colombiano) for previous exploration efforts in the area, such as geologic, geophysical, and geochemical datasets. The results of our work include 2D permeability, heat, and geothermal favorability models. These results highlight that the area with the most potential to host geothermal fluids is centered underneath the volcanic edifice (∼ 8 km2): an elongated area that coincides with the intersection of the regional Cali-Patía and local Río Guabo and Azufral-Sapuyes fault zones. The results also suggest that the area with the most geothermal favorability is likely related to the potential upflow of the geothermal system, and the warm springs surrounding the volcano are likely related to the structurally controlled outflow. Finally, our results illustrate the value of applying the Play Fairway Analysis approach at a local scale to integrate different types of data and to identify areas with the most potential to host geothermal resources in geothermal zones.