Work

Petrophysical signature of the Salobo IOCG deposit: Insights into lithology, hydrothermal alteration, and mineralization

Year: 2026

Type: article

Abstract: • Multi-source data integration improves models, enhancing exploration accuracy. • Salobo’s IOCG deposit shows differents petrophysical signatures across zones. • A petrophysical log was developed for Salobo’s sub-zones. • Main minerals of each sub-zone were associated to Salobo’s petrophysical and geophysical signatures. • A conceptual framework connects key datasets within the Salobo deposit. The integration of petrophysical and mineralogical data is essential for understanding variations in the physical properties of hydrothermally altered rocks. In this study, petrophysical data were combined with mineralogical analyses obtained through TIMA (TESCAN Integrated Mineral Analyzer), QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy), and LIBS (Laser-Induced Breakdown Spectroscopy core scanner) to characterize the petrophysical footprint of the Salobo IOCG (Iron Oxide Copper-Gold) deposit. The analysis and interpretation of rock physical properties and mineral mapping data reveal that the Salobo alteration zones exhibit distinct petrophysical signatures. The calcic-sodic alteration zone is characterized by low density (∼2.89 g/cm 3 ), low magnetic susceptibility (∼0.091 SI), and moderate resistivity (∼2781 Ω.m). A newly identified Ca-Fe-K subzone marks the transition from Ca-Na to Fe- and K-enriched systems, presenting a slight increase in resistivity (∼2958 Ω.m). Iron enrichment zones display systematic transitions, progressing from grunerite-dominated associations to almandine-rich zones and magnetite precipitation. These zones are distinguished by high density (>30 g/cm 3 ), elevated magnetic susceptibility (up to 7.516 SI), and increased chargeability (∼62.2–89.7 mV/V). The K-Fe subzone and its advanced forms are characterized mainly by almandine and biotite, along with intense late chloritization that significantly affects petrophysical signatures. Potassic alteration displays a strong decrease in resistivity (∼1658 Ω.m), attributed to biotite and sulfides. This study highlights the importance of integrating multi-source data to enhance the understanding of mineral systems through mineralogical and petrophysical datasets. Petrophysical properties, controlled by mineral composition, provide insights into Salobo’s geophysical signature and petrophysical footprint. Thus, a schematic model was developed to illustrate the petrophysical signature of each subzone hydrothermal alteration zone, linking variations in density, magnetic susceptibility, resistivity, and chargeability to mineralogical data. The presented methodology provides a framework applicable to other IOCG deposits, similar systems, and potential targets, enhancing exploration efficiency and providing valuable strategies for advancing mineral exploration on a broader scale.

Source: Ore Geology Reviews

DOI: 10.1016/j.oregeorev.2026.107119