Regional mapping of phyllic- and argillic-altered rocks in the Zagros magmatic arc, Iran, using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and logical operator algorithms

摘要

A method for regional mapping of phyllic and argillic hydrothermally altered rocks using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data was developed and tested at the Cuprite, Nevada, calibration and validation site, and then extensively used in the Zagros magmatic arc in Iran, which consists of the High Zagros and Jebal Barez Mountains, and the Bazman volcanic area. Logical operator algorithms were developed to perform multiple band ratio and threshold value calculations, which can be applied to a scene using a single algorithm, thus eliminating separate production and application of vegetation and dark pixel masks. Argillic and phyllic band-ratio logical operators use band ratios that define the 2.17 µm and 2.20 µm absorption features to map kaolinite and alunite, which are typical in argillic-altered rocks, and muscovite, which is a common mineral in phyllic-altered rocks.