Comparison between Airborne Geophysical and ASTER Data for Hydrothermal Alteration Mapping for Exploration of Copper Mineralization



The study area covers the northern part of the Baft geological map (scale of 1:100 000 ). Several porphyry and vein-type mineralization are reported from this area. A topic that is discussed in the mineral exploration community is the use of remote sensing and airborne geophysics for porphyry type mineralization. Which one is more reliable and efficient in hydrothermal alteration mapping? Airborne geophysical data and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images of this area were analyzed and compared for hydrothermal alteration mapping. ASTER data was analyzed by using shortwave infrared (SWIR) bands by applying principal component analysis (PCA) and band ratioing, in order to enhance the altered areas. Band ratios such as 4/9, 7/9 ad 7/6 were used for hydrothermal alteration enhancement. After applying PCA, principal component 3 could enhance the hydrothermal alteration. Airborne geophysical data was analyzed by applying principal component analysis and ratioing techniques. The higher K radiometric values, as was expected, are not entirely associated with hydrothermal alteration. There are anomalous values that are associated with the lithologies that are rich in K-bearing feldspars. The overall evaluation of satellite and geophysical data shows that ASTER data is more accurate in terms of hydrothermal alteration mapping than geophysical data in this area. Nevertheless, this point should be taken into consideration that the geophysical data can detect both surface and sub-surface anomalies. The combined use of both data sets is recommended for hydrothermal alteration mapping.