Abstract: Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image processing have been used for mapping hydrothermal alteration in Eastern Iran. Eastern Iran has a great potential for the discovery of different types of mineralization. This technique works very well in eastern Iran due to low precipitation causing very minor soil development and the small amount vegetation and therefore good rock exposure. ASTER images processing can identify areas with hydrothermal alteration for further exploration. Application of ASTER false color composite images, color composite ratio images, principal component analysis and Spectral Angle Mapper (SAM) techniques detected five altered areas in the district of SW Birjand, Eastern Iran. Spectral Angle Mapper (SAM) classification proved to be the best method for mineral mapping. This technique shows very good results for identification of different type of alteration with distinct mineral assemblages. The SAM method has also detected argillic and alunitization zones in areas that had not been clearly recognized by earlier techniques.

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