Light Stable Isotope (O, H, C) Signatures of BIF-Hosted Iron Ore Systems: Implications for Genetic Models and Exploration Targeting

Abstract Stable isotope data from hypogene (i.e., below the line of weathering) iron oxides and gangue minerals BIF-hosted ore deposits in Australia, South Africa, Brazil have significantly assisted constraining different hydrothermal fluid sources flow models during upgrade BIF to ore. The δ 18 O values on paragenetic stages enrichment display a consistent decrease unenriched (4–9‰) as low −10‰ for high-grade This large shift oxygen is interpreted evidence enormous incursion ‘ancient’ meteoric water into fault fracture zones at time Archean Paleoproterozoic time. paragenetically early > 4‰ suggest involvement magmatic fluids greenstone belt-hosted Carajás-type deposits, basinal brines basin-hosted Hamersley-type deposits. In contrast, late stage metamorphosed, basin hosted Quadrilátero Ferrífero 6‰. reflects renewed deep crustal, (metamorphic or magmatic) influx. Carbon carbonates hydrothermally altered indicate that carbon latter not derived units, but represents either case within underlying stratigraphy systematic distal proximal alteration zone, including may be used geochemical vector. this case, analyses provide potential exploration tool, particularly targeting extension bodies entirely concealed which hematite/magnetite are frequently only mineral can readily analysed.