Age, tectonic geography and provenance of the Renner Group, Tomkinson Province, Northern Territory

Abstract

The informally termed greater McArthur Basin is a Paleoproterozoic to Mesoproterozoic multiphase basin system that records a billion years of Earth’s history within the Northern Territory. Sedimentary successions that make up the basin preserve evidence for events that surround the basin during its formation. In this study we present LA-ICP-MS detrital zircon U–Pb, Lu–Hf and REE data that provide new constraints on the Renner Group and reveal provenance variations that exemplify the evolution of the basin. Using the youngest, near-concordant, zircon grains, the maximum depositional age for each formation is determined. The maximum depositional age for the Gleeson Formation has been constrained to later than 1600 ± 42 Ma. Grains from the Sweetwater Member, Grayling Member and Powell Formation provide maximum depositional ages of 1624 ± 37 Ma, 1554 ± 77 Ma and 1714 ± 50 Ma, respectively. As well as using U-Pb in zircon, we also look at U-Pb in detrital rutile. These data yielded ages of 1731 ± 39 Ma (Sweetwater Member), 1811 ± 45 Ma (Grayling Member) and 1703 ± 32 Ma (Powell Formation determined by the youngest, near concordant grain). Age variations within the stratigraphy propose a subtle change from older, Paleoproterozoic sources to additional input from younger sources. Formations in the Renner Group record age peaks that are consistent with rocks of the Aileron Province, Mount Isa Inlier and the Gawler Craton. By comparing U-Pb and Lu-Hf data, the Renner Group correlates with the Roper Group (McArthur Basin), South Nicholson Group (South Nicholson Basin) and the Tijunna Group (Birrindudu Basin). In particular, the Powell Formation of the Renner Group is equivalent to the Bessie Creek Sandstone of the Roper Group, and shares similarities with the Wondoan Hill Formation of the Tijunna Group. On the other hand, the Grayling Member, Sweetwater Member and Gleeson Formation are equivalent to the older formations of the Lower Roper Group such as the Arnold Sandstone and Crawford Sandstone. I suggest that the variation in provenance records the exhumation and exposure of these regions as a result of intracratonic rifting and magmatism from 1.5 – 1.4 Ga. The increase in 1860–1650 Ma detritus suggests uplift of the Arunta region.