Geothermal Resource Base for South America: A Continental Perspective

Abstract

Recently updated data sets on crustal seismic velocities, gravity anomalies, radiogenic heat production, terrestrial heat flow and thermal springs have been employed in outlining regional variations in the thermal characteristics of the South American continental lithosphere. A 2ox2o grid system was adopted for data processing and in determinations of vertical distributions of excess temperatures. The results obtained have lead to an improved understanding of the tectonic control on the occurrence of geothermal resources and allowed estimates of resource base. It has been possible to identify more than 20 crustal blocks where the resource base per unit area, referred to the accessible depth limit of 3 km, are in the range of 1013 to 1014 Joules. The area extent of the blocks ranges from several tens to hundreds of kilometers. Most of high temperature resources occur within the well known sectors of magmatic activity in southern and central Chile, Altiplano region in Bolivia, and several localities along the magmatic arc covering western Ecuador, central volcanic belt of Colombia and southern Venezuela. In addition, isolated pockets of geothermal resources are found to be present along the western Andean belt in Peru. There are indications pointing to occurrence of medium temperature geothermal resources at depths of 3 to 5 km in some sectors of the eastern parts of the continent, mainly in the northeastern and central parts of Brazil. The results have also allowed better assessments of low temperature resources of the Guarani aquifer system, which span over large areas of southern Brazil, western Uruguay and northern Argentina.