Mapping hydrothermal alterations for mineral potential using band ratio and principal component analysis on Landsat 8 imagery over Nasarawa, North-Central Nigeria

This study maps hydrothermally altered minerals in Nasarawa, North-Central Nigeria, using Landsat 8 OLI imagery to support sustainable mineral exploration. Through an integrated workflow of band ratio and Crosta principal component analysis, significant iron oxide, ferrous, and hydroxyl alteration zones were delineated across the complex transition between the Pan-African basement and Cretaceous sedimentary formations. Key findings indicate that iron oxide alterations (Ratio 4/2) are extensively concentrated over the Awgu Formation, while hydroxyl-bearing minerals (Ratio 6/7), indicative of argillic-phyllic alteration, exhibit a strong spatial correlation with NW–SE trending tectonic lineaments within the Lafia-Wukari alluvium and basement complex. This structural alignment suggests that regional fault systems acted as primary conduits for mineralizing hydrothermal fluids. The high spatial agreement between these spectral “hotspots” and documented mineral occurrences from NGSA validates the effectiveness of this remote sensing approach in the Middle Benue Trough. By integrating Sabin’s band ratios with Crosta-based PCA, this research provides a robust, cost-effective predictive framework for identifying high-potential targets in difficult-to-access terrains. We recommend prioritizing these structurally controlled alteration zones for systematic geochemical sampling, offering a strategic model to reduce exploration risks and support Nigeria’s economic diversification into the solid minerals sector.