Alteration Detections Using ASTER Remote Sensing data and Fractal Geometry for Mineral prospecting in Hemich Area, NE Iran.

Nowadays, remote sensing studies are considered as one of the best methods in mineral prospecting. Considering that most of the important deposits of the world, such as porphyry copper and epithermal gold deposits are widely associated with alteration zones. Identification of the alterations can be a significant exploratory guide for these types of deposits. The spectral difference between altered and unaltered rocks is the most important way of detecting alteration areas and thus exploring ore deposits by means of remote sensing. In this research, ASTER image was used to identify alteration areas in the Hemich Area, NE Iran. Geometric corrections were made on images in order to reduce the spatial errors caused by displacements and distortions related to sensors. Radiometric corrections were also applied to reduce the spectral errors caused by atmospheric effects. Subsequently, mineral prospectus areas were identified using false-color composite, band ratio, and principal components analysis. Since the results of these methods are grayscale images, a concentration-area fractal method was used to distinguish the regions containing the alterations. Using the results of these methods, some areas with the highest probability of mineralization were discovered, which were compatible with the ground control points.