Multispectral discrimination of spectrally similar hydrothermal minerals in mafic crust: A 5000 km2 ASTER alteration map of the Oman–UAE ophiolite

Multispectral remote sensing of hydrothermal alteration in volcanogenic massive sulfide (VMS) ore systems mafic crust is relatively uncommon, part due to the short-wave infrared spectral similarity several key minerals: epidote, chlorite, actinolite, and serpentine. In this study, we developed regional mosaic generation classification workflows for Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) imagery discriminate these minerals over entire Semail ophiolite (Oman–UAE). Spectral discrimination was achieved through adaptation ASTER (pre-)processing workflow specific mapping targets, available datasets, location study. Necessary steps included pre-selection scenes without residual atmospheric water features, normalization based solely on overlapping target outcrops, correcting cross-mosaic ramp errors, map image-derived reference data. The resulting map, validated comparison with field sampling, most areally extensive continuous survey yet presented oceanic crust, providing a renewed framework research mineral exploration Earth's largest ophiolite. Our confirms that vast majority upper regionally altered spilite type secondary assemblage. Localized areas epidosite alteration, marking focused flow paths, are confined whereas previously unrecognized but intense actinolite common both lower crust. methodological developments expand standard considerations necessary geological using image mosaics. They further demonstrate underappreciated capability multispectral data spectrally similar rock types. Although specifics method necessarily optimized Oman–UAE ophiolite, re-optimization local should allow results be other well-exposed mafic-hosted VMS districts.