Multi-proxy geophysical delineation of structurally controlled hydrothermal copper mineralization: a case study from Wadi Nesyrin and Wadi Ager, Southwest Sinai, Egypt

Abstract

Located within the Neoproterozoic Arabian–Nubian Shield of South Sinai, this study integrates geological and geophysical investigations in the Wadi Nesyrin and Wadi Ager regions to delineate subsurface copper mineralization. Given the region’s documented surface occurrences, research focused on identifying high-priority mineral targets within the crystalline basement. A ground radiometric survey across 876 stations revealed three anomalous zones (A, B, and C) hosted in calc-alkaline granites. Diagnostic radioelement ratios eU/eTh (1.8–3.2) and eU/K% (0.9–2.5) indicate significant uranium enrichment and hydrothermal mobilization under oxidizing conditions. Subsequent high-resolution surveys including VLF-EM, Turam-EM, and Vertical Magnetic Gradient (VMG) identified nine major anomalies. Fraser filtering of VLF-EM tilt-angle data delineated conductive bodies striking NE–SW, NW–SE, and N–S, aligning with regional tectonic trends. Quantitative modeling estimates the depth of these causative sources between 45 m and 127 m. The spatial correlation between high radiometric ratios, negative VMG anomalies, and strong EM phase shifts confirms that mineralization consists of structurally controlled, sulfide-bearing quartz veins (chalcocite, bornite, and chalcopyrite). The novelty of this study lies in the first integrated application of airborne radiometric, ground gamma-ray spectrometric, VLF-EM, Turam-EM, and vertical magnetic gradient (VMG) data to delineate structurally controlled hydrothermal copper mineralization within this previously underexplored granitic terrain. The proposed hierarchical exploration workflow demonstrates how regional radiometric anomalies can be progressively refined using complementary geophysical methods to prioritize drilling targets and reduce exploration uncertainty.