Assessment of image ratio technique: Targeting structural features and mineralization characteristics in the southwestern part of the Sokoto Basin in Nigeria using Landsat 8 imagery

Abstract

Landsat 8 used multispectral images to map surface structures and validate the existence of suspected mineral alteration zones in the southwestern part of the Sokoto Basin in Nigeria. The area falls within contrasting sedimentary, metasediment, metamorphic, and older granitoid lithologies. The processing and analysis of the Landsat 8 imagery involving false color composite (FCC), band ratio, and principal component analysis (PCA) were implemented in the visible near-infrared and short-wave infrared bands of Landsat 8. PCA highlighted areas with high concentrations of clay minerals and iron oxides using RGB composite bands 7, 5, and 3. Moreover, PCA enhanced iron oxide, hydroxyl-bearing minerals, and likely prospective zones mainly constrained in amphibolite, phyllite, quartzite, and alluvial deposits that have undergone metamorphism and metasedimentation within Yegiwa and Kurege. It identified iron ore and clay mineral alteration, suggesting the occurrence of manganese, goethite, and carbonate minerals around Maburo and Derrena. The observed alteration zones and their associated quartz veins are usually consistent with the main NE–SW provincial structural trend dipping to the northwest zone. However, field verification validates rock units typically consisting of muscovite, hornblende, manganite, tourmaline, quartz vein, and granitic rocks. Accordingly, remote-sensing and field verification served as a guide for future subsurface structural investigation and in-depth geophysical exploration.