Identification and field verification of Fe-bearing rocks in the Hasançelebi region (Malatya, Türkiye) and its vicinity using ASTER and Sentinel-2A images

Abstract

In this study, image processing has been applied to ASTER and Sentinel-2A satellite images, and obtained data is used to reveal Fe-bearing rocks in the vicinity of Hasançelebi (Malatya), close to Divriği (Sivas) which is one of the most important iron provenances in the Central-Eastern Anatolia region of Türkiye. Remote sensing images, particularly the visible-near-infrared (VNIR) and partially shortwave infrared (SWIR) bands, have been employed to identify Fe-bearing minerals and rocks. With the purpose of identifying Fe-bearing minerals and rocks, various band rationing processes have been applied. Supervised classification which utilizes a parallelepiped algorithm has been employed on the resulting ratio images to create classification distributions for Fe-bearing minerals. According to the classification results; ferrous iron (Fe²⁺) and ferric oxides are more associated with ophiolitic rocks, ferrous silicates and ferric iron (Fe³⁺). The distributions are generally associated with clastic lithologies, and laterite and gossan appear to be associated with volcanic and plutonic rocks. Because of the different band widths in the VNIR range, Sentinel-2A classifications have the highest pixel count when compared to ASTER classifications for the same surface areas. During fieldwork, rock samples representing the lithologies and Fe-bearing minerals in the region have been collected and mineralogical-petrographic, geochemical, and XRD analyses have been conducted on these samples. Additionally, for spectral mineral identification and to compare Fe-bearing minerals with other analysis results, spectral signatures have also been obtained from the same samples via Analytical Spectral Device (ASD). In extracting features such as lineaments and faults, which play a crucial role in the development of ore deposits along the structural discontinuities, digital elevation models (DEM) have been preferred instead of optical images. When lineament analysis results and iron deposits, which had been identified in previous studies, were overlapped, it has been detected that revealed iron deposits are predominantly associated with the Ciritbelen-Otmangölü Fault (COF) which is an approximately east-west trending strike-slip fault located in the study area, along with other related fault systems. They are generally distributed within an ophiolitic slice and the surrounding magmatic intrusions.