Spectral angle mapping, spectral information divergence, and principal component analysis of the ASTER SWIR data for exploration of porphyry copper mineralization in the Sarduiyeh area, Kerman province, Iran

Abstract

The study area is located in the southern part of the central Iranian volcano-sedimentary complex (Uromiyeh-Dokhtar belt), southeast of Kerman province. The advanced space-born thermal emission and reflection radiometer (ASTER) shortwave infrared (SWIR) bands enabled the generation of maps designed to represent the presence of minerals such as kaolinite, muscovite, and chlorite which are important in the identification of hydrothermal alteration related to porphyry copper mineralization. The purpose of this paper is to enhance alteration in the Sarduiyeh area, using spectral angle mapper (SAM), spectral information divergence (SID), and principal component analysis (PCA) methods. The individual principal component images generated by directed principal component analysis (DPCA). This investigation resulted in the identification of three groups of alteration minerals, namely: (1) sericite-illite, (2) kaolinite-montmorillonite, and (3) chlorite-calcite-epidote. Results of these methods were validated by field sampling and further laboratory studies. The findings showed that SAM and SID are suitable methods as compared with DPCA for mapping alteration minerals. The altered zones were sampled and subjected to X-ray diffraction (XRD) analysis. The spectra of few samples representing the hydrothermally altered rocks were also measured. Microscopic studies of the thin sections were conducted. Field observations revealed that all of the known copper mineralized localities occur within the interpreted alteration areas.