Hydrothermal alteration and structural mapping of the Qolqoleh-Kasnazan shear zone in Iran using remote sensing data

In recent years, a variety of remote sensing data have been widely used in mineral exploration, particularly at the reconnaissance stage for mapping alteration zones and investigating the relationship between tectonic structures and target mineralization. Moreover, different image processing methods such as band ratios, dimensionality reduction, and classification have been developed for enhancing target features in various mineralization systems. The Sanandaj-Sirjan metamorphic zone in Iran is a potential zone for different types of metallic mineralization, such as copper, molybdenum, and gold. Contrary to other metallic deposits, only a few studies have been carried out to map gold deposits in this region using remote sensing data. This study aims to map tectonic lineaments and those alteration zones known to be relevant to orogenic gold deposits in the Qolqoleh-Kasnazan shear zone, a portion of the Sanandaj-Sirjan zone in the southwest of Saqez, Iran. We use two well-known and efficient image processing methods, i.e., band ratios and principal component analysis, for processing ASTER images and mapping alteration zones. Moreover, we map tectonic lineaments using the first principal component of Landsat 8 data. The study of alteration zones and lineaments reveals a major trend of NW-SE for gold mineralization in the study area. It is observed that mineralized zones are associated with iron oxides and argillic alteration zones and the phyllic alteration is predominant at the margin and away from the center of mineralization zones. © 2021, Saudi Society for Geosciences.