CuBAS – Sediment-hosted Cu, Mansfield Basin, VIC

The prospectivity for a sedimentary basin to host copper is often hindered by the lack of understanding of the mineral system at play. In this project we investigated copper-mineralised legacy drill core hosted by the Geological Survey of Victoria.

The Geological Survey of Victoria and CSIRO carried out a collaborative project (2022-2023) aimed to investigate the potential of the Mansfield Basin as a sediment-hosted copper mineralisation target. During the project, core was logged sedimentologically, scanned and photographed for spectral mineralogy (HyLogger), mapped geochemically by XRF (Minalyze, Maia Mapper) for identification of copper. Petrographic studies were carried out to identify diagenesis and relative timing of mineralisation. The outcome was used to characterise the mineralisation with regards to depositional environment, sedimentary facies, diagenetic processes, and potential style of mineralisation.

The main new results of the project include identification of mineralisation of copper oxides is associated with organic wood and plant matter deposited in crevasse splays as part of the terrestrial, clastic alluvial fan to floodplain setting under arid, evaporitic conditions. The mineralisation shows affinities to roll front type deposits associated with what is generally referred to as redbed-type Cu mineralisation.