Assessment of the provenance of the Willyama Supergroup and similarities with the Mt. Isa Inlier sedimentary succession

Project Investigator

Doctor Karin Barovich

Project details

A link between the Paleoproterozoic Willyama and Cloncurry terrains has been suggested nearly 20 years ago (Laing and Beardsmore, 1986), and more recently Page & Sun (1998) and Page et al., (2000, 2003) have shown direct temporal similarities. However as yet, there has been little compositional comparison that would allow direct correlation of units between the Curnamona Province and the Mt Isa region, or comparisons between source terranes for the sedimentary successions of each area.

Geochemical and isotopic provenance studies can highlight similarities, if any, between source terranes for the sedimentary sequences in the two terrains.

Geochemical and Nd isotope data from the Olary and Broken Hill Domains has allowed the correlations to be strengthened between the sedimentary successions across the basin.

The Willyama basin sedimentary rocks are remarkably enriched in incompatible and rare earth elements, when compared to other Paleoproterozoic sedimentary sequences or to PAAS (Post-Archean Australian Shale).

Based on the geochemical and isotopic data, and in combination with an abundance of detrital zircons of about 1780 Ma (Page et al, 2000) in the Willyama sediments, we suggest a central and northern Australian source terrane for the sediments is most logical. This conclusion strengthens links between the Willyama basin and the economically valuable Mt Isa district.

Mt. Isa district geochemical and isotope data is not currently available to allow us to compare the average ages of source terranes for the two areas. A direct linkage of the Olary and Broken Hill Domains to the Mt. Isa Inlier through a shared sedimentary provenance would be important for Proterozoic reconstruction models.

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