Mapping hydrothermal alteration zones associated with known Pb–Zn potentials in central and southern Afghanistan: an application of ASTER data

Hydrothermal alteration mapping is an important tool for early‑stage mineral exploration, particularly in regions where field access is limited. This study systematically applies established ASTER‑based band ratio (BR) and Selective Principal Component Analysis (SPCA) techniques to map hydrothermal alteration zones potentially associated with Pb–Zn occurrences in two contrasting geological settings in Afghanistan: a carbonate-hosted setting in Bamyan (Central Afghanistan) and a skarn setting in Kandahar (Southern Afghanistan) The integrated spectral indices delineated iron oxide, carbonate, phyllic, argillic, and granitic‑related alteration zones that spatially coincide with known Pb–Zn occurrences, mapped lithologies, and major structural features. Comparison with USGS‑defined Pb–Zn halos and published geological maps showed good spatial agreement, with 77% (Bamyan) and 79% (Kandahar) of reference points falling within the mapped alteration zones. The results provide a preliminary basis for prioritizing targets for field verification in remote and mountainous terrains of arid and semi‑arid regions.