Multi-approach analysis: A sedimentary lithological mapping approach using ASTER data in the Karak region, Pakistan

Remote sensing techniques have evolved into very prolific tools for lithological mapping of geological resources. It offers valuable information regarding the structural configurations and spatial disposition of intricate lithologies. This study employs the use of ASTER-based remote sensing techniques with the integration of field surveys and spectroscopic analysis to map lithological units within the Kohat sub-basin of the NW Himalayas. To study the lithological variations in the basin, we employed the potency of multi-spectral (ASTER) data for assessment of lithological distribution in the study area. During analysis, various spectral image transformation techniques were applied with the integral approach of minimum noise fraction (MNF) and band ratio transformation (BRT). The results from the analysis suggest that the MNF transformations minimized spectral noise and increased formation separation, and the BR composites (3/2, 5/1, and 7/2) successfully mapped clay-rich, alluvial, and carbonate deposits in the region. The carbonates, anhydrites, and silicates diagnostic absorption features were also confirmed spectroscopically at ~2.30-2.35 µm, ~1.45-1.90 µm, and ~2.20 µm, respectively. The overall accuracy was 80.1%, and the Kappa coefficient was 74.94% when validated. The novelty of this work is the use of systematic application and cross-validation of field analysis, ASTER processing, and spectral transformation analysis under different formations. In conclusion, this research shows the effectiveness and reliability of remote sensing techniques and mineral spectroscopy coupled with field validation in the lithological characterization of the sedimentary zone of the Kohat sub-basin.