Geochemical anomalies of Cu–Mo in the southeastern part of Jiroft, Kerman Province, Iran: evidence for a new porphyry copper district in the southern sector of the Urumieh–Dokhtar Magmatic Belt

The Urumieh–Dokhtar Magmatic Belt (UDMB) is a major metallogenic province in Iran, hosting several Cu ± Mo ± Au porphyry deposits. The southeastern part of Jiroft, Kerman Province, lies within this belt, where contrary to previous studies, recent field reconnaissance implies that volcanic rocks of the area are intruded by unexplored fertile Cu-bearing intrusive bodies. In this region, supergene alteration has also caused the impregnation of surficial stockworks with malachite and iron oxide/hydroxides, especially in the central parts, where fertile quartz diorite units are exposed. Mo mineralization is observed at a distance from the centre of the porphyry system. Rock units of the study area show clear alteration zones that can be easily differentiated. Potassic alteration, located mostly in the central parts, is covered by phyllic, argillic and propylitic alteration at shallower depths. In the present study, systematic sampling of rock units, including 309 lithogeochemical samples with 28 vein samples containing quartz + malachite, was carried out. Anomaly maps of Cu–Mo were analysed using classical statistics (median + nStev), multifractal concentration–number (C-N), concentration–area (C-A) and singularity index (SI) methods. Using the fractal C-A method, we obtained threshold limit values of 79.43 ppm for Cu and 15.85 ppm for Mo, which reflect the intensity of the anomaly and the presence of primary mineralization, supergene and enrichment phases. Weak anomalies and those that were hidden between the background with the enriched and depleted areas for Cu–Mo were determined using the SI method.