Laboratoire de Génie Civil, Géosciences et Sciences Géographiques, Institut National Polytechnique Félix Houphouët-Boigny, Yamoussoukro BP 1093, Côte d’Ivoire
The regolith mapping of the SML concession of the Nigerien Liptako of West Africa has been established by using LANSAT 8 images and topographic position index (TPI). Regolith units were extracted from band reports. The 5/7 ratio has been used to distinguish clay minerals, the 3/1 ratio has been used to determine iron oxide materials and that 4/2 to distinguish ferruginous materials. The colore composition of the band 572 by assigning respectively RGB permitted for unsupervised classification because this assignment showed moderately the regolith units. Discrimination of landforms has been realizedand performed by IPT. The superposition of the regolith map and that of the relief and the control work in the field made it possible to validate the final regolith units map. This method made possible to classify the regolith units into four groups: alluvial sediments (Da), sedimentary rocks of the “terminal continental” horizontally covering Birimian rocks (Dc), altered and “saprolitized” Birimian rocks sometimes covered by sand, soil or outcrop by the underlying fresh rock (Es) and a layer of sand from the disintegration of rocks of the “terminal continental” and horizontally covering the Birimian rocks (Rs). The study showed that approximately 70% of the study area is ideal and more than 30% has a negative impact on geochemical exploration for gold and therefore requires specialized sampling techniques. This shows that the method used is effective in mapping regolith units in the Nigerien Liptako and also in similar areas.