Integrated remote sensing and GIS analysis for uranium exploration: a case study of the Falea deposit, Taoudeni basin (Western Mali)
Abstract
Relevance and the purpose of the work. Uranium is a critical energy resource with steadily growing demand. Explo ration in remote regions of Africa, such as the Taoudeni Basin in western Mali, is hindered by limited accessibility, high costs, and outdated geological maps. The Falea polymetallic deposit (U–Ag–Cu) represents an unconformi ty-associated sandstone-hosted system. This study aims to develop an effective, low-cost methodology for identifying exploration criteria for uranium mineralization using Landsat-8 OLI data combined with spectral indices, Principal Component Analysis (PCA), and fuzzy logic modeling. Methods of research. A cloud-free Landsat-8 OLI Surface Reflectance image (March 9, 2024; Path 201, Row 051) was used. Six reflective bands (2–7) were processed. Image analysis included: 1) calculation of band ratios 4/2 (iron oxides), 6/5 (ferromagnesian minerals), and 6/7 (clay minerals) with anomaly thresholds set at mean+2σ; 2) PCA ap plied to the six bands to separate mineralogical variations; 3) fuzzy logic integration of the resulting layers to produce a prospectivity map. All operations were performed in QGIS using GDAL and SAGA GIS. Results of the work. Band ratio 4/2 revealed linear iron oxide anomalies spatially associated with the Road Fault sys tem. Ratio 6/7 delineated extensive clay alteration areas (6.6% of the study area) along the main structural corridor, while iron oxide anomalies covered 3.6%. An RGB composite (6/5,4/2,6/7) visualized polymineralic associations; known ore zones appear as yellow-orange patches. PCA effectively separated alteration types: PC3 – iron oxides, PC4 – ferromagnesian minerals, PC5 – clay minerals. Fuzzy logic modeling identified three high-potential zones, two of which coincide with known mineralization and one representing a new exploration target in the northwestern sector. Conclusion. The integrated use of Landsat-8 OLI data with band ratios, PCA, and fuzzy logic provides a cost-effective, reproducible workflow for uranium exploration in the Taoudeni Basin. Quantitative estimates (3.6% iron oxide anom alies, 6.6% clay anomalies) can serve as a basis for field exploration planning. The methodology is applicable to similar sandstone-hosted unconformity-related uranium deposits in other intracratonic basins of Africa