Verdugo-Ihl and 2 co-authors reported in 2017 that hematite is the dominant gangue component of the Olympic Dam Cu-U-Au-Ag orebody, South Australia. A distinct oscillatory-zoned hematite, conspicuously rich in ‘granitophile’ elements (U, W, Sn, Mo) is recognized throughout the ~2 km vertical extent of deposit zonation, from deep pyrite-chalcopyrite to shallow bornite-chalcocite ore zones, as well as throughout the entire NW-SE strike of the orebody.
Concentrations of granitophile elements are retained, albeit at lower concentrations, in later replacement hematites. Comparison of trace element datasets for U-W-Sn-Mo-zoned hematite relative to replacement hematite provides evidence for localized fluid-mineral reaction and for the importance of reactions
coupling dissolution with reprecipitation rates in driving element exchange.
The oscillatory-zoned hematite is analogous to that previously dated by LA-ICP-MS, confirming that this generation of hematite was formed at ~1.6 Ga during the onset of the IOCG mineralising system. Such ‘granitophile’-rich hematite may be common in other IOCG deposits, and typifies precipitation from fluids rich in these elements during the main hydrothermal stages.
Lack of evidence for this type elsewhere is most likely attributable to advanced overprinting in which such signatures are largely obliterated.
Managed & Built by I2M Consulting, LLC | © 2010-
