Employing multiple prospectivity mapping and exploration targeting, a case study from the Sonajil porphyry copper deposit, north-western Iran

The main goal of this study is to demonstrate how fusion methods can be used in mineral prospectivity mapping (MPM) through a comprehensive multi criteria decision-making (MCDM) analysis. MPM plays a crucial role in mineral exploration by aiming to lower exploration expenses through identifying potential ore-bearing targets and planning detailed exploration surveys, including drilling. This study utilises various methods including index overlay, Old TOPSIS, Modified TOPSIS, Adjusted TOPSIS, Old VIKOR, Modified VIKOR, fuzzy gamma operator, fuzzy ordered weighted averaging (FOWA) with different strategies, and fuzzy inference system (FIS). The study area chosen for comparison of various fusion techniques is the Sonajil Cu-Au porphyry deposit located in the east Azerbaijan province, which is the main focus of the investigation. Geological factors, including rock units and faults, remote sensing data for alteration, geochemical analysis using soil samples, and geophysical factors from reduced to the pole magnetic data, are employed in the indicator maps to assess the potential of the region. To delineate the prospective area in terms of ore-trapping favourability, a fractal-based analysis was applied to all fusion outputs, resulting in the identification of five distinct perspective areas. The efficacy of different MPMs was assessed and compared using subsurface data from 21 boreholes, showing consistent agreement rates among all methods. The FIS showed a 79% agreement, whereas the FOWA, with its optimal strategy, exhibited an 81% agreement, emphasising their effectiveness compared to alternative approaches. The predicted maps show a close connection with the geological features of the host rock, particularly granitoid and andesite porphyry from the Sonajil formation, along with the presence of potassic and phyllic alterations. The FIS and FOWA models have successfully pinpointed new drilling sites and assisted in evaluating mining potential for future exploration and development. By utilising this comparative model, which evaluates different algorithms to determine the most accurate prediction map, significant progress has been made in exploratory studies.