Skarn-style alteration in Proterozoic metasedimentary protoliths hosting IOCG mineralization: the Island Dam Prospect, South Australia

Abstract New mineralogical, geochemical, and geochronological data are presented for the Island Dam prospect, Olympic Cu-Au Province, South Australia. Skarn assemblages comprising actinolite/phlogopite + K-feldspar magnetite suggest presence of calcareous protoliths at indicate high-temperature alkali-calcic alteration in early stages IOCG mineralization, as seen other deposits region. Dating lamellar hematite intergrown with Cu-Fe-sulfides allows timing alteration-mineralization event to be constrained 1594 ± 28 Ma, contemporaneous ~ 1.59 Ga mineralization recorded across eastern Gawler Craton. The host metasedimentary sequence can correlated Wallaroo Group based on lithology fabrics, stratigraphically by an underlying 1850 Ma Donington Suite granite new U–Pb ages superimposed mineralization. Oscillatory zoned silician skarn displays a trace element signature comparable that observed outer shell deposit nearby Wirrda Well prospect is consistent geochemical signatures from banded Fe-rich rocks share common enrichment W, Sn, Mo, Th, U IOCG-style Relative As, Sb, Ni, Co is, however, specific iron-oxides rocks. These features attributed pre-existing iron-rich lithologies.