Join us as we explore the geology of the remarkable Winu-Ngapakarra copper-gold-silver deposit in Western Australia's Great Sandy Desert, a discovery that's reshaping our understanding of mineral potential in the Paterson Orogen. Discovered by Rio Tinto Exploration in late 2017, Winu represents a unique new deposit style and is generating significant excitement for future exploration.Key Takeaways from this Episode:Location and Regional Context: The Winu deposit is situated within the Paterson Orogen, a NNW-trending belt of folded and metamorphosed Proterozoic rocks in northwestern Australia. This region is considered an important and developing mineral province. The deposit itself sits on the Anketell Shelf, a Proterozoic basement high within the Paterson Orogen, largely covered by younger sedimentary rocks.Host Rocks and Metamorphism: Mineralization at Winu is hosted in metamorphosed sub-arkosic sandstones, siltstones, minor greywackes, mafic rocks, and calc-silicates. These rocks are preliminarily correlated with the Lamil Group, specifically the upper Malu Formation, which also hosts the renowned Telfer deposit. The rocks underwent regional metamorphism up to upper greenschist/lower amphibolite facies, with a contact metamorphic overprint, often visible as altered porphyroblasts.Structural Story: The deposit's structure is dominated by a NNW-trending, W-verging monocline, interpreted to have formed during the older Miles Orogeny (~820-810 Ma). This structure was later refolded during the Paterson Orogeny (~550 Ma), leading to the formation of a half-domal structure at Winu. Key regional features include the Thorny Devil Fault, a significant NW-trending normal fault that separates the Winu and Ngapakarra deposits.Intrusion-Related Mineralization: Winu is classified as a wall rock-hosted, intrusion-related copper-gold deposit, genetically linked to granite intrusions. Geochronology dates the main mineralization stages (V2 and V3A) at approximately 658 to 655 Ma, while later veins (V4) are dated around 619.0 ± 8.1 Ma.The "Bismuth Collector Model" for Gold: A fascinating aspect of Winu is that gold precipitation is thought to have occurred via the bismuth collector model. This process involves hydrothermal fluids, initially above 270°C and relatively reduced, forming a bismuth (telluride) melt that efficiently scavenged gold from the gold-undersaturated fluid. Textures show a progression from native bismuth and gold (maldonite) to tellurobismuth minerals and then bismuthinite associated with sulfides. This suggests an early gold system was overprinted by a later copper system.Hydrothermal Vein Systems: The deposit features multiple generations of hydrothermal veins: Early Stockwork (V1), Early Mineralized (V2), Main Stage (V3A-D), Late Quartz Veins (V4), and Late Fractures/Breccias (V5).Supergene Enrichment: The upper parts of the Winu deposit, those not covered by mudstones, show supergene upgrading of mineralization to depths averaging 200 m, and locally up to 340 m. This has resulted in the formation of minerals like chalcocite, malachite, and chrysocolla.Exploration Significance: The discovery of Winu as a significant intrusion-related copper-gold deposit opens up substantial future exploration opportunities in this relatively underexplored part of Australia, particularly in the concealed northern extension of the Paterson Province.Sources:⁠Winu Deposit Summary Report⁠⁠Australian Mines Atlas⁠⁠Rio Tinto Website⁠⁠PorterGeo Database - Winu-Ngapakarra⁠⁠Geology of Winu-Ngapakarra, Great Sandy Desert of Western Australia⁠⁠The Winu-Ngapakarra deposit in the Great Sandy Desert of WA⁠⁠MEGWA18 May 2022: The Winu-Ngapakarra Copper Gold Deposit⁠ (YouTube)⁠Winu Blog Post⁠Disclaimer:AI generated content created using Google's NotebookLM.

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