The forgotten Mesoproterozoic of Northern Australia: a chemostratigraphy and detrital zircon study of the greater McArthur Basin

Abstract

The informally named greater McArthur Basin is a regionally extensive Proterozoic ‘super basin’ system located across northern Australia. The region hosts large and proven hydrocarbon reservoirs as well as high grade mineralisation. The deposition system is divided into ‘packages’; rocks of similar lithology, age and stratigraphic position. Although studies have begun to constrain intra-basin correlation, tectonic setting and depositional environments of the enclosing Wilton and Glyde Packages, very little is known about the Favenc Package. In this study, we present new, high resolution geochemical isotopic data (rare earth, trace and major elements) as proxies for the palaeoenvironment and redox conditions of the Mount Rigg Carbonates. Cerium anomalies, Y/Ho and Zn/Fe ratios of carbonate-rich facies show evidence for restrictive and anoxic basin-wide conditions through the deposition of the Dook Creek, Limmen and Mainorou Formations. Furthermore, rare earth elements and yttrium (REY) distribution patterns of these carbonates also reflected a lacustrine environment. In addition, new U–Pb, Hf and REE data of detrital zircons within the Favenc and Wilton Packages are also presented to investigate correlation and provenance of stratigraphically similar groups. Using the youngest concordant grain, the Dook Creek Formation is interpreted to have a maximum depositional age of 1614 ± 78 Ma. ƐHf(t) values of the unit ranges between -28.09 to 18.89. Findings in this study were then incorporated together to develop a tectonic and deposition model for the Mesoproterozoic greater McArthur Basin.