Hematite geochemistry and geochronology resolve genetic and temporal links among iron-oxide copper gold systems, Olympic Dam district, South Australia

摘要: Abstract The Wirrda Well and Acropolis prospects, ~25 km south from the Olympic Dam deposit, are among several dozen examples of iron-oxide copper gold (IOCG) mineralisation forming a 600 km-long province in eastern Gawler Craton, South Australia. IOCG systems across differ terms host lithology, mineral associations, intensity brecciation, grade Cu-(U)-Au mineralisation. Previous efforts to provide geochronological framework for mineralisation, correlate this with igneous activity, were inhibited by lack clear crosscutting features (particularly breccia-hosted systems) scarcity reliable hydrothermal geochronometers. earliest generation hematite, characterised enrichment U-W-Sn-Mo previously reported Dam, provides confident U-Pb dates insights into fluid signatures. Similar hematite is recognised Acropolis, allowing direct comparison between three systems. Relationships early, silician (Wirrda Well) titaniferous (Acropolis) magnetite U-bearing at two prospects differ. Inferred martitisation has generated zoned U-W-Mo-enrichment constant Sn concentration, but marked loss REE + Y (REY) Ti, whereas Well, single-crystal resembling that retains high REY concentrations. Although morphologies, textures compositions vary significantly, common (laser ablation-inductively coupled plasma-mass spectrometry) age ~1590 Ma obtained most data (207Pb/206Pb: 1598.9 ± 6.3 Ma 1590.6 ± 6.5 Ma Acropolis). geochemical signatures iron-oxides share trends U, W, Sn, Mo, field strength siderophile elements, comparable Fe-oxides ‘outer shell’ deposit. Given datable would seem be ubiquitous phases throughout commonality geochemistry district significant, as it single, traceable compare province.