Classification of geothermal systems in Madagascar

Abstract

Classification schemes for geothermal energy sources have recently been improved to include the concept of geothermal play. Our comprehensive review for the island of Madagascar aims to enhance the understanding of the factors controlling the country’s geothermal energy sources. The result is the first catalogue of geothermal systems in Madagascar. The geothermal systems of six prospective areas were categorized into three classes using the geological and tectonic context combined with the temperature of the potential geothermal reservoir. The three classes are (1) graben border-fault liquid-dominated moderate-temperature (Ambilobe and Miandrivazo areas), (2) fossil magmatic liquid-dominated moderate-temperature (Ambanja, Itasy and Antsirabe areas), and (3) sedimentary liquid-dominated low-temperature (Morondava Basin). The hydrothermal resources of Madagascar are commonly associated with extensional domains referred to as geothermal plays. A conceptual model was developed for each prospective area to better understand the factors controlling the heat source, formation permeability and fluid migration. Our results can be used to guide exploration strategies and have implications for assessing and quantifying Madagascar’s geothermal potential.