Tyler, Ian1; Kohanpour, Fariba1; Gorczyk, Weronika1
1Centre for Exploration Targeting, School of Earth Sciences, University of Western Australia, Perth WA 6009, Australia
The Neoproterozoic (<911 Ma to >655 Ma) Yeneena Basin is exposed at the northeastern margin of the West Australian Craton, deposited on extended crust of the Archean Pilbara Craton and the Proterozoic Capricorn Orogen. It is deformed and metamorphosed within the Proterozoic Paterson Orogen and hosts the world-class Telfer Au–Cu mine. The recent Winu Cu–Au discovery is focussing exploration interest under Canning Basin cover.
An understanding of the tectonic setting and geodynamic history of the Yeneena Basin can be derived from published data, enhanced by new information extracted from key exploration and stratigraphic drillholes held in the Geological Survey of Western Australia Core Library, including rock properties, structural analysis and petrography, geochemistry, geochronology, isotope geology, sedimentology and sequence stratigraphy. When integrated with geophysical imagery, including gravity, magnetics and passive and active (reflection) seismic surveys, it can form the basis of a consistent crustal-scale 3D map, which can be used as a framework to understand the geodynamic evolution of the basin and it’s mineral systems.
In the Yeneena Basin, the lower Throssell Range Group occurs between the Vines Fault, and the Southwest Thrust to the west and the Parallel Range Thrust to the east. The basal Coolbro Sandstone, which has a low magnetic signature, unconformably overlies the 1.8 to 1.3 Ga crystalline basement of the Rudall Province, and is overlain by the Broadhurst Formation, a sequence of carbonaceous and sulfidic shale, sandstone and dolomite that extends beneath shallow cover to the northwest. The overlying Isdell Formation is predominantly carbonate and is overlain in the Parallel Range Thrust zone by the Lamil Group comprising the Malu Formation (quartz sandstone), the overlying Puntapunta Formation (carbonate, sandstone, shale and siltstone) and the Wilki Formation (quartz sandstone and shale).
The Tarcunyah Group in the adjacent North West Officer Basin is part of the 850–700 Ma Supersequence 1 of the Centralian Superbasin. It includes a basal siliciclastic package, which unconformably overlies the Archean Fortescue Group west of the Vines Fault, and an overlying shallow-water shelf evaporate-carbonate package, which contains distinctive stromatolite assemblages. In magnetic images, a transition can be seen from the non-magnetic evaporate-carbonate package across the Southwest Thrust and into the non-stromatolitic and magnetic sedimentary rocks of the Broadhurst Formation. This is consistent with the Throssell Range Group comprising deeper water, basin floor deposits, laterally equivalent to Supersequence 1.
The sediment-hosted Nifty Cu deposit has been dated at 823–791 Ma, and can be linked to 830 Ma mafic intrusions emplaced during basin extension. Inversion of the basin by southwest verging thrusting and associated dextral strike-slip faulting took place during the Miles Orogeny at 655 Ma. Au–Cu and W mineralisation is associated with intrusions of the 650–610 Ma Mount Crofton Granite east of the Parallel Range Thrust. To the north and east of Telfer, the upper Lamil Group is buried by less than 300 m of Phanerozoic sedimentary rocks deposited in the overlying Canning Basin. Important elements for Au-Cu mineralisation targeting can be identified in geophysical images.
Fariba Kohanpour has completed her PhD in February 2019 in the Centre for Exploration Targeting. she applied geodynamic modelling, geophysical interpretation, and isotope analysis to understand tectonic evolution of the Halls Creek Orogen. Now she is doing her postdoc for investigating geodynamics of Paterson region.