Controls on the genesis and emplacement of komatiite-hosted Ni–Cu–PGE-sulphides at Albion Downs (Agnew-Wiluna Belt,Western Australia): A case study on the development of PGE lithogeochemical vectors to Ni–Cu–PGE-sulphide deposits
Restricted accessResearch articleFirst published online December, 2007
Controls on the genesis and emplacement of komatiite-hosted Ni–Cu–PGE-sulphides at Albion Downs (Agnew-Wiluna Belt,Western Australia): A case study on the development of PGE lithogeochemical vectors to Ni–Cu–PGE-sulphide deposits
Albion Downs is a structural domain within the Agnew-Wiluna Greenstone Belt of Western Australia, which contains one of the most highly Ni-endowed komatiite sequences in the world. Albion Downs comprises adcumulate-textured pods and lenses, which are flanked by thinner meso- and orthocumulate-textured units. Basal massive nickel-sulphide mineralisation (e.g. Jericho) generally occurs in the thinner meso- and orthocumulate-textured units, whereas stratabound disseminated nickel-sulphide mineralisation (e.g. Jordan) is hosted in the largest adcumulate-textured pod. After reaching sulphide-saturation, basal massive sulphides formed in settings where magma flow was less fast and turbulent than in channels. Conversely, in channellike settings sulphide blebs were entrained in the flow, thus forming disseminated sulphides. Platinum-group element lithogeochemistry indicates that the signature associated with the oreforming process is only recorded <100 m-away from nickel-sulphide mineralisation, where samples display a positive relationship between Pd+Pt and MgO and Pd+Pt and S. Conversely, the PGE signature of samples collected farther away is not directly controlled by sulphide segregation. Understanding the scale at which ore-formation processes operate is crucial to the development of any lithogeochemical exploration vector that is dependent on PGE variation.
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