Structural and alteration zones controls on Cu mineralisation in the northwest of Nain (northeastern Isfahan, Iran): A remote sensing perspective

Remote sensing data can be utilised for regional mapping of the Earth's surface to enhance structural interpretation and mineral prospecting. To this end, satellite multispectral sensors such as the Advanced Space borne Thermal Emission and Reflectance (ASTER) with six channels in the shortwave infrared and five channels in the thermal area is helpful in detecting alteration and mineralisation zones in areas with good rock exposures. This study has investigated and detected hydrothermal alteration zones and mapped structural elements associated with mafic volcanic rocks-related copper mineralisation in the northwest of the Nain district in Central Iran. In this study, we processed ASTER data (14 bands). We generated maps that depict the distribution of alteration minerals (e.g., sericite, kaolinite, chlorite, and calcite) related to copper mineralisation using various techniques such as different band ratio images, False-colour composition (RGB), Matched Filtering (MF), and Spectral Angle Mapper (SAM). Follow-up ground proofing validated the analysis of results from the ASTER data. The study established the regional distribution of hydrothermal alteration zones (i.e., phyllic, argillic, and propylitic). The regional distribution and extent of these alteration zones are associated with regional structures that served as focusing conduits for the buoyant hypogene mineralizing fluids. The results show that ASTER imagery is useful in mapping the extent of the hydrothermal alteration and lithological units and can thus be used to target hydrothermal ore deposits with large alteration footprints.