The Winu-Ngapakarra deposit in the Great Sandy Desert of Western Australia, a Neoproterozoic Intrusion-related Cu-Au-Ag deposit

The Winu Cu-Au-Ag deposit was discovered in late 2017 and is hosted in metamorphosed sandstones and siltstones and lesser mafic rocks which are most likely correlatives of the upper Malu Formation of the Yeneena Basin. The deposit structure is dominated by a gently SSE plunging inclined monocline. Copper-gold mineralisation occurs in at least four en-echelon left stepping lodes with strike lengths between 350 and 750m, northerly trends and moderate easterly dips. These higher-grade lodes are surrounded by a more extensive halo of low-grade mineralisation. In detail mineralisation is hosted by numerous brittle veins and breccias with progressively cooler and more oxidised mineral assemblages. Textures suggest that gold precipitated from a bismuth melt (bismuth collector model). Several stages of barren fractures, breccias and faults as well as thin dolerite dykes cut the mineralisation. A well-developed supergene chalcocite blanket overlies the primary mineralisation at Winu. Re-Os dating of molybdenite intergrown with chalcopyrite yielded Paterson Orogeny ages for the mineralised veins at Winu. Element associations and vein and alteration textures and mineralogy classify Winu as an intrusion related Cu-Au-Ag deposit of Neoproterozoic age genetically related to an as yet unidentified granitoid pluton.