Evaluation of geothermal resources in a hotspot realm: Mauritius Island (Indian Ocean)

Geochemical and geothermal investigations were performed in the Mauritius Island, located along the Seychelles-Mascarene Plateau, aimed at the preliminary assessment of possible geothermal resources. The central part of the island may be the most suitable as characterized by the most recent volcanic activity (0.03 Ma). Geochemical analyses of water samples collected from this area indicate no mature water and the chemical features are ascribable to short-term water-rock interaction in shallow hydrogeological circuits. A gradient borehole was drilled and thermal logs performed after complete thermal equilibration to evaluate the thermal gradient in central part of the island. A value of 43 °C km-1 was measured and a similar result was obtained by logging a deep well no longer used for water extraction. The results point to a weak or null deep-seated thermal anomaly beneath Mauritius. This might mean that the deep thermal processes (mantle plume) invoked to occur in the hotspot area do not likely yield any particular thermal signature.