Hydrothermal Alteration Mapping for Geothermal Exploration in Manda-Inakir Area, NW of the Republic of Djibouti
[Djiboutian Office Of Geothermal Energy Development, Djibouti]
Adopted in different domains, remote sensing is the science of obtaining information about an area through analyzing data collected by a device or a sensor without direct contact with the object under investigation. In a geothermal survey, this technique can be useful during the prefeasibility stages of exploration. The area of this study is located in the Afar depression in East Africa. This depression is the result of a triple junction of three rifts: the continental East African Rift, the Gulf of Aden, and the Red sea oceanic Rifts (Vellutini, 1990). Among the geological characteristic structures of Afar depression, the Manda-Inakir axial zone will be the center of this research. Situated in NW part of the Republic of Djibouti, it extends ENE-WSW across the boundary with Ethiopia. This is a predominantly basaltic unit and strongly fractured in NW-SE direction. Based on the last geothermal prospect of the Republic of Djibouti in 2014, the area is considered as a potential geothermal resource area for the country. Despite the lack of geophysical or geochemical data, this paper aims to map hydrothermal alterations of the Manda-Inakir area by using remote sensing to provide the basis for future geothermal investigations. A Landsat 8 OLI image of this site has been used. Preprocessing was the first step by carrying out an atmospheric correction (FLAASH) with Envi 5.3 software. Then the False Color Composite (FCC), Band ratio (BR) and a Combination of Band ratio methods have been applied for distinguishing the hydrothermal alteration. The different maps have been edited with ArcMap software. Finally, the resulted maps show the presence of hydrothermal alteration minerals in several zones in Manda-Inakir field that could become targets for further geothermal exploration.
|        Topic: Exploration||Paper Number: 11057|