| Abstract |
The Lake Abhe geothermal prospect is located in south-western part of the Republic of Djibouti. The stratoid basalt outcrops affected by the main tectonic trends, E-W and NW-SE, delineating high plateaus and plains, control the geological setting. It is one of the thirteen geothermal fields potentials identified in Djibouti. The Lake Abhe prospect is characterized with several surface hydrothermal manifestations such as fumaroles, hot springs, altered zones, hot soils and numerous massive travertine constructions aligned upon the main faults trend. The hot spring manifestations are mainly located in the bottom of the travertine with high temperatures of more than 90°C. The chemical profiles of the hydrothermal source are alkaline-chloride in general and some bicarbonate from the previous studies. Recently surface exploration was done in this site with technical support from ISOR in collaboration with ODDEG team. This survey was undertaken between November 21th up to December 14, 2015, using all the technique of surface exploration (Geology, Geochemistry, and Geophysicist) and using different methods like MT, TEM. Several soundings was carried out using MT and TEM equipment’s and all gravity sounding were carried out using Scintrex equipment’s. The data quality was fine except for few soundings, located very close to Lake Abhe .The quality of the data improved in general significantly when processed with the magnetic data from the Remote Reference station. Several water samples was collected (including fumarole sample) and addition to that, stable isotopes of oxygen and hydrogen, chlorine and boron and analyzed in ISOR laboratory. The previous study done by CERD in 2012 show conductive zones from 900 m up to 1500 meters before showing higher resistivity. These deep conductive zones could identify with the heat source in this region that would lead to the geothermal resources of the Lake Abbe. However, this news exploratory campaign will allow ODDEG to model clearly the geothermal reservoir using a 2D inversion and target the well sitting for feasibility phase. |