| Title | Geological Study of Lake Abhe, Geothermal Field, Djibouti |
|---|---|
| Authors | Youssouf Hassan SAMOD, Sigurður G KRISTINSSON |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Graben, Lake Abhe, Afar depression, Travertine, Fault |
| Abstract | Lake Abhe is located in the Afar depression, close to the borders between Ethiopia and Djibouti. The direction of the Aden Gulf (WWN-EES) predominates clearly thus giving the orientation of the Abhe Lake Graben. The origin of the graben and its evolution is evidenced by different fault systems which are of normal types and shear zones. The major faults of the area are the ~N120E (WNW-ESE) normal faults that are intersect with NNW, N-S, and NE trending faults, cutting this area in a series of horsts and grabens. The stratigraphy of the Abhe Lake is formed mainly by volcanic rocks of an age ranging between 3.5 and 1 Ma. Geochemical studies suggest that the geothermal reservoir is not connected to Lake Abhé or the local groundwater. The geothermal reservoir in Lake Abhe area is fed by meteoric water mainly from the regional aquifer. Most of the hot springs at Lake Abhe is concentrated close to the travertine chimney near the lake; there main direction is striking E-W. The fumaroles are controlled by the main WNW-ESE fault system. Compared to the thermal springs near Lake Abhe, the fumaroles are characterized by a fault breccias and reddish clay. The Lake Abhe basin in particular, seems to be linked to the oldest deformities episodes, less tectonically active in Late Quaternary if compared to younger basins such as the Asal one to the East. The main interest in this study is to understand the tectonic evolution of the site as well as the structural setting controlled the geothermal system. |