Middle-late Mesoproterozoic tectonic geography of the North Australia Craton: U–Pb and Hf isotopes of detrital zircon grains in the Beetaloo Sub-basin, Northern Territory, Australia

Abstract

The upper Beetaloo Sub-basin of the McArthur Basin, Northern Territory, Australia, records over 500 million years of tectonic history of the North Australian Craton from ca. 1.45 to 0.9 Ga. The basin sequences include shallow-water clastic sedimentary rocks that preserve the oldest global commercial hydrocarbon reserves. New detrital zircon U–Pb age and Lu–Hf isotopes, compiled with published data, provide constraints on the basin provenance and reveal the dynamic tectonic evolution of Mesoproterozoic northern Australia. Data from the oldest formation examined, the ca. 1.4 Ga Bessie Creek Sandstone, suggest provenance from (present-day) eastern sources (e.g. the Mount Isa Province and the palinspastically adjacent Curnamona and Georgetown provinces) with considerable spatial heterogeneity. These eastern source regions are interpreted as uplifted rift-shoulder highs, formed by contemporaneous extension between Proterozoic Australia and Laurentia. Progressively younger formations (the Velkerri Formation, the Moroak Sandstone and the Kyalla Formation) demonstrate a rapid swamping of the basin by detritus from southerly sources (e.g. the Arunta Region) that occurred at ca. 1.4–1.3 Ga. This is particularly characterised by the up-section reduction of ca. 1.6 to 1.5 Ga detrital zircon grains. This change in provenance is interpreted to relate to closure of an ocean basin during the period 1.35 to 1.25 Ga, which resulted in uplift of the southern margin of North Australia Craton. Three ungrouped latest Mesoproterozoic to Neoproterozoic sedimentary units, the lower and upper Jamison sandstone and the Hayfield mudstone, were deposited after the emplacement of the Warakurna Large Igneous Province and are sourced from the Musgrave Province. Detrital zircon U–Pb and Hf isotope affinities between the lower and upper Jamison sandstone and the Hayfield mudstone, and the latest Mesoproterozoic to early Neoproterozoic successions along the eastern margin of the North China Craton, suggest that they share a similar provenance. This supports correlations between the Mesoproterozoic of the North China Yanshan Basin and the greater McArthur Basin.