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Table 3 Geological and geothermal characteristics for prospective areas in Madagascar

From: Classification of geothermal systems in Madagascar

Region North Central West Source
Area Ambilobe Ambanja Itasy Antsirabe Miandrivazo Morondava
Dominant geological formations Sandstone and shale of the Isalo and Sakamena groups Paragneiss and migmatite of the Sambirano Group Migmatitic gneiss, paragneiss and schist of the Ambatolampy Group Orthogneiss and tonalitic-granite of the Dabolava Suite Sandstone, limestone, clay and marl of the Isalo, Sakamena groups Interpreted from geological maps
Temperature of hot springs (°C) 47–78 48–72 24–57 38–57 30–55 39–42 Hambinintsoa et al. (2017)
Gunnlaugsson et al. (1981)
Besairie (1959)
Temperature of geothermometer (°C) 140–180 140–200 170–240 150–240 140–170 120–140 Gunnlaugsson et al. (1981)
Dominant chemical composition of fluids Moderate to high CO2 (200–1000 ppm) and low Cl (< 300 ppm) High CO2 (1000–4000 ppm) and Cl (400–500 ppm) Low CO2 < 200 ppm and moderate Cl (500–1200 ppm)
Saline brine, NaCl-dominated
Basinal or infiltration fluids?
Hambinintsoa et al. (2017)
Gunnlaugsson et al. (1981)
Mobile fluid phase in the geothermal reservoir Liquid-dominated Interpreted according to temperature of geothermal reservoir