Processing of ETM+ Data for Alteration Mapping A Case Study: Chahmir, Iran

Many ore deposits are first detected in the field by the recognition of hydrothermally altered host rocks, and are typically zonally distributed. Ore deposits are often produced by fluid flow processes that alter the mineralogy and chemistry of the country rock. One of the main reason for extention using a multi-spectral and hyperspectral sensor is due to detect the optical characteristics of the Earth's surface using hundreds of spectral bands. All previous studies show that remote sensing has a important impress to detection alteration zones one of the most important steps in exploration studies is indicating the productive geological units that are the result of surface features caused by effective factors in forming a deposit. Thus, Figuring out the regions with potential of a hydrothermal alteration could be one of the important factor in recognizing the regions of these deposits. In this study We used different image analysis methods such as Ls-fit and Crosta method and Band Ratio and False Color Composite methods for detection of mineralogy and alteration on a set of ETM-H data of Chahmir zone, central of Iran. At the end We identified several alteration minerals within the study area. We successfully detected and mapped hydrothermal alteration and minerals such as chlorite minerals, epidotes and gypsum . The result shows hydrothermal alteration, which can be a model in indicating the productive units in this region.

Keywords:

Chahmir zone , alteration mapping , ETM-H data , Ls-fit method , Crosta method , False Color Composite , Band Ratio