Hydrogeochemistry and hydrothermal alteration of the Hanle geothermal field, Djibouti-East Africa

Authors : Ali Ferat Bayram, Moussa Hassanleh Hassan

Pages : 462-468

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Publication Date : 2025-06-30

Article Type : Research Paper

Abstract :This study focuses on the geochemistry and hydrothermal alteration of the Hanle geothermal field (Djibouti-East Africa). Water from five drinking water wells, a hot spring and a steam condensate in the Hanle graben was analyzed for major and minor hydrogeochemical parameters. Analyzed items for water samples (hot spring water, groundwater, and steam condensate) are pH, electric conductivity (EC), SiO2, Cl, SO4, HCO3, F, Na, K, Ca, Mg, Al, Fe, B, As, δD, δ18O. Using the chemical compositions and saturation indexes of the hot springs, the reservoir temperature was estimated at around 120 to 125 °C. Based on the XRD analysis, the clay minerals smectite, chlorite and illite, as well as quartz, calcite, and alunite, were determined as alteration minerals in this region, which represent high temperature environment (>180 °C). The obtained data suggest that the water in the Hanle region was likely formed either by the mixing of groundwater and heated fossil seawater, or by the dissolution of evaporite by heated groundwater.
Keywords : Hidrotermal alterasyon, Hanle, Cibuti, Jeokimya

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