ASTER and Sentinel-2MSI Remote Sensing Data for Mapping Iron Oxide-Bearing Zones, the Case of Central Afghanistan

This study maps iron oxide–bearing zones in the northern Markazi Behsud District of Wardak Province, Central Afghanistan, using a comparative analysis of ASTER and Sentinel‑2 MSI data. Multiple remote sensing techniques, False Color Composites (FCC), Band Ratios (BR), Principal Component Analysis (PCA), the Crosta method, and the Spectral Angle Mapper (SAM), were applied to identify iron oxides and discriminate minerals such as magnetite, hematite, and goethite. This study newly established band ratios based on mineral spectral properties enhanced detection performance. The newly established spectral ratios, derived explicitly from diagnostic ferric and ferrous absorption features, differ from conventional band ratio schemes by offering improved sensitivity to iron‑bearing mineral variations and more robust delineation of hydrothermal alteration zones in multispectral data. Sentinel‑2 MSI produced markedly superior results compared to ASTER due to its higher spatial resolution and seamless single‑tile coverage. Among all methods, the Crosta technique and SAM were the most effective, with SAM showing the strongest agreement with USGS permissive mineralization zones. The integrated results delineate a continuous iron‑bearing belt approximately 54 km long and 6.8 km wide along the Baba Mountains. The overall accuracy of 71.3% demonstrates the strong capability of Sentinel‑2 MSI, particularly when combined with SAM, for mapping iron oxide–rich zones in structurally complex terrains.