Iron oxide and hydroxyl enhancement using the Crosta Method: a case study from the Zagros Belt, Fars Province, Iran

Abstract Following preliminary reports on the probable occurrence of iron ore in the Mashayekh-Nowdan area, west of Shiraz, principal components analysis on 6 and 4 Landsat-TM bands was tested by the Crosta method for the enhancement and discrimination of iron oxide stained and hydroxyl-bearing areas in the region. Eigenvector loadings of visible and infrared bands of TM bands 1, 3, 4, 5, and 7 show that in each case the first principal component (PC 1) indicates albedo, PC2 indicates the difference between visible and infrared bands, and PC3 indicates vegetation. Features with lower importance such as iron oxide or hydroxyl-bearing minerals are concentrated in subsequent principal components. PC4 of unstretched data transformation on bands 1, 4, 5, and 7 indicates the hydroxyl-bearing and carbonate exposures; and on bands 1, 3, 4, and 5, it indicates iron oxides. Color composites of hydroxyl and iron oxide images enhance the iron oxide exposures, but not as clearly in the case of hydroxyls, because of some spectral behavior similarities with carbonates.