Use of spectral analysis for detection of alterations in ETM data, Yazd, Iran

Abstract

Spectral analysis methods were used for detection of mineralogical features on a set of Enhanced Thematic Mapper Plus data of Behabad zone, central Iran. Several indicative minerals for hydrothermal alterations were identified in the study area. The spectra of unknowns were determined by comparing to USGS mineral spectral library. Different pre-processings and processings were performed to achieve the highest possible accuracy. These are the minimum noise fraction, the pixel purity index analysis, spectral feature fitting, spectral angle mapper and binary encoding. The results of spectral analysis, as a map of minerals abundances, along with the results of other Image processing methods such as least square fit, and Crosta method were integrated within ArcGIS Software to achive a potential map of hydrothermal alterations. The minerals: allanite, magnetite, alunite, clay minerals, and muscovite were therefore detected and mapped in this study. The detected alterations here highly match to the mineral concentrations which are formerly found and measured in the study area that emphasizes the reliability of the applied method.