4 research outputs found
WITHDRAWN: Calcrete-hosted surficial uranium systems in Western Australia: Prospectivity modeling and quantitative estimates of resources PART 2 â Prospectivity modeling and exploration targets
Isotopic insight into the Proterozoic crustal evolution of the Rudall Province, Western Australia
© 2018 The Authors The Proterozoic assembly of Australia involved the convergence of three main Archean cratonic entities: the North, West and South Australian Cratons, and is recorded in the Proterozoic orogenic belts surrounding these continental nuclei. The Rudall Province of northern Western Australia is the sole exposure of a Paleo- to Mesoproterozoic orogen lying between the North and West Australian Cratons, and may record the effects of their amalgamation. We present new zircon O, UâPb and LuâHf isotope data from magmatic rocks across the Rudall Province, to which we add existing isotope data to yield a crustal evolution overview. Hf evolution trends for the ca. 1804â1762 Ma Kalkan Supersuite, the ca. 1589â1549 Ma Krackatinny Supersuite and the ca. 1310â1286 Ma Camel Suite, indicate a significant input of Archean East Pilbara Basement material, albeit as a mix with more juvenile material, including a possible ca. 1900 Ma component. Zircon d18O data suggest a contribution from supracrustal material into the magmatic source of the Kalkan Supersuite, which may have been emplaced in an extensional setting. In contrast, the Krackatinny Supersuite and Camel Suite have mantle-like d18O which may reflect partial melting of deeper Archean sources. Geochemical data for the Krackatinny Supersuite shows geochemical trends implying that melting of thickened mafic crust progressed from deeper to shallower levels, possibly in a rift setting. Camel Suite K-rich leucogranites may also have been emplaced in an extensional setting towards the end of high-P metamorphism. All terranes of the Rudall Province are para-autochthonous with respect to the Pilbara Craton, with no requirement for arc-related magmatism. We outline two potential scenarios for the Paleo- to Mesoproterozoic geodynamic evolution of the Rudall Province: an early cratonic amalgamation between the West and North Australian Cratons ca. 1680 Ma followed by Mesoproterozoic intraplate events; or a later assembly ca. 1377â1275 Ma. We lean towards this later amalgamation scenario