Use of aster images for the detection of iron in the deposits of continental terminal 3 (Ct3) in the Arewa region, southwest of the Iullemmeden basin in Niger.

The present study was carried out in the south-western part of Niger. The study area corresponds to the Arewa region, which is located in the southwestern part of the Iullemmeden basin. The general objective of this work is to highlight the effectiveness of the ASTER image in mapping areas with showings of iron mineralization in the Continental Terminal 3 (Ct3) formation. Specifically, these areas are identified with major indices of iron oxides and hydroxides (Fe2O3 – Fe(OH)2) and goethite Fe(OH)3. The methodology implemented is based on band ratios and indices as well as the Main Component Analysis (PCA) were applied to the ASTER image of the study area and allowed the detection and mapping of anomalies related to the presence of iron in the Continental Terminal 3 formation. The band ratios applied to the bands of the ASTER image were very useful for mapping the distribution of iron in the study area and allowed to differentiate the spatial distribution of ferrous iron (Fe2+) and ferric iron (Fe3+) in the area. The Band 1/Band 2 and Band 2/Band 1 ratios were used to detect the spatial distribution of ferrous iron (Fe2+) and ferric iron (Fe3+) of the study area, respectively. The results of the Principal Component Analysis (PCA) were very effective in detecting iron-associated minerals or groups of minerals in the area. The presence of iron oxide is predicted by Aster bands 1, 2 and 4 in CP3, which are distinguished by bright pixels. CP6 reveals negative effects of bands 7 and 8 on Fe(OH)-containing minerals.