Hydrothermal Alteration Mapping Using Image Processing Techniques - Case Study: Meshgin Shahr-Ahar

In this research, hydrothermal alteration zones in Meshgin Shahr – Ahar area, located in the north-west of Iran, have been investigated using image processing techniques of remotely sensed data. Landsat ETM+ images have taken in 29/7/2002 was used for mapping alteration. General alteration trend in the area was mapped by conventional methods consisting Color Composite, Band Ratio, Principal Component Analysis, Crosta technique and Density Slicing. Detailed mineral mapping also carried out by using analysis of spectral library data.The results achieved from different methods indicate same alteration trend in the study area. The accuracy from Crosta technique relative to the ancillary alteration data was 81.95%. The accuracy achieved from analysis of spectral library data and density slicing were respectively 53.24% and 49.37%