Mapping and discrimination of mineralisation potential of the Baïbokoum pluton (Southern Chad), using Landsat 9 OLI images and field observations

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Abstract The Baïbokoum region is located in the Adamawa-Yadé domain of the Pan-African Chain in Central Africa. In this study, the discrimination of lithological units producing altered deposits and iron oxides was investigated by combining data from fieldwork and Landsat 9 OLI data. Several digital mapping techniques were used, in particular the combination of red-green-blue (RGB) colors, principal component analysis (PCA), and minimum noise fraction (MNF). Consequently, other satellite image processing methods, such as band ratios (BR) and the Spectral Angle Mapper (SAM) classification algorithm, were applied to target and delineate altered deposits and corresponding minerals, and were used to classify the lithological units in the study area. The selected digital mapping methods identified syenites, diorites, and gneisses containing iron oxides, hydroxyl/clay, and ferrous occurrences as potential mineralizations in the Baïbokoum region. Lineament analyses are obtained automatically using the PCI Geomatica line tool and revealed three major trends (NE-SW, E-W, NNE-SSW, and NW-SE) surrounding altered rocks recognized as containing iron oxide and hydroxyl mineral deposits. In the field, these lineaments can be grouped into three deformation phases. Phase D1 (NW-SE), phase D2 (N-S to NNE-SSW) and phase D3 (E-W to NW-SE). This result suggests that combining (Landsat 9) data and field data can simplify the identification of rock units containing a potentially mineralized zone.