An enhanced magnetic signature map to increase the probability of success in mineral prospectivity mapping

An enhanced magnetic signature analyzing algorithm was proposed to deal with two following challenges of mineral prospectivity mapping (MPM) in coming decades: (1) the necessity to focus on complex exploration of conceal or covered porphyry copper deposits (PCDs) and (2) lack of innovative processing algorithms to delineate magnetic signatures of PCDs with higher predictive ability and lower degree of uncertainty. The advantages of proposed algorithm can be summarized as follows: (1) increasing the probability of success since it is found on formation model of PCDs, (2) reducing judgment and model-related uncertainties, (3) decreasing exploration search space rapidly with lower costs and (4) capability to handle the discovery of conceal PCDs. The algorithm, which includes following steps, was implemented on ground magnetic data of Sardoiyeh area in southeast of Iran: (1) identifying circular geological features (porphyry targets) using radial symmetry transformation, (2) detecting center of features with none-maximum suppression and thresholding, (3) highlighting the extent of features by employing amplitude contrast transformation and (4) determination of size and geometry of prospective targets using active contour algorithm. The results were evaluated by alteration zones resulted from remote sensing data processing, geological map, 3D Cu isoshells derived from drilled exploration boreholes and field works. All six previously known porphyry copper deposits/occurrences in the study area have been delineated successfully, and a strong correspondence has been observed between delineated targets and 3D Cu isoshells (≥ 0.2%). Approximately 15% (1.5 of 10.1 km²) of the study area has been delineated, and at least 18 new prospective targets with first priority have been proposed for further exploration. The presence of porphyry mineralization has been approved in 7 proposed targets by geological field works.