Sub-pixel mapping of iron-bearing minerals using ALI data and MTMF algorithm, Masahim volcano, SE Iran

The Advanced Land Imager (ALI) data were applied to sub-pixel mapping of iron-bearing minerals at the Masahim composite volcano, SE Iran. Key minerals including goethite, jarosite, and hematite were distinguished via the analysis of spectral reflectances of field samples. The imagery endmembers were extracted using field and laboratory spectra as references; then, the target minerals were mapped using mixture-tuned matched filtering (MTMF) algorithm. Iron-bearing minerals were mainly enhanced at the central facies, generally associated with argillic and phyllic alteration units. In addition, goethite and hematite were mapped in the proximal facies. The coefficient of determination (R-2) was calculated to assess the accuracy of sub-pixel maps. The R-2 coefficient was 0.67 for goethite, 0.54 for jarosite, and 0.49 for hematite. It is concluded that ALI data are useful for mapping and detecting iron-bearing minerals. However, misclassification of goethite and hematite could be the main source of errors.