Geothermal exploration in the republic of djibouti: thermal and geological data of the hanlé and asal areas

• Published in: Geothermics 1990, Vol.19 (6), p.561-582
• Main Authors: Zan, Leonardo, Gianelli, Giovanni, Passerini, Pietro, Troisi, Carlo, Haga, Abdourahman Omar
• Format: Article
• Language: English
• Subjects: Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Geochronology; Geothermics; Isotope geochemistry. Geochronology; Tectonics. Structural geology. Plate tectonics
• ISSN: 0375-6505; 1879-3576
• DOI: 10.1016/0375-6505(90)90005-V

During geothermal exploration in the Republic of Djibouti in the period 1987–1989, two deep wells were drilled in the Hanlé area and four in the Asal area. The two wells at Hanlé encountered low temperatures (maximum recorded temperature was 124°C at 2020 m depth). Volcanic rocks of Miocene age were found at the bottom of one Hanlé well. Minor recent crustal stretching may account for the absence of any significant thermal anomaly. The four wells at Asal met high temperatures (up to 358°C at 2095 m depth), and high-enthalpy fluid was produced from two of them. Drilling data and new structural studies contribute to the development of a model for the Asal Rift, which is characterized by very steep faults with no evidence of flattening at depth and by the migration of the spreading axis from southwest to northeast. The authigenic mineral assemblage studied in all the wells is in good agreement with the measured temperatures in five of the six wells.