Detrital zircon U-Pb-Hf isotopes redefine sedimentary continuity and crustal growth in the southern Mount Isa Inlier, North Australian Craton

Detrital zircon U-Pb-Hf isotopic analysis was applied to metasedimentary rocks from the Dajarra region, southern Western Succession of the Mount Isa Inlier, to constrain maximum depositional ages (MDAs), provenance, and crustal evolution. Twelve samples from key stratigraphic units were analysed, including the Mount Guide Quartzite, Eastern Creek Volcanics, Jayah Creek Metabasalt, Timothy Creek Sandstone, Warrina Park Quartzite, Moondarra Siltstone, and Kallala Quartzite. MDAs vary significantly from those of units mapped as stratigraphic equivalents in the northern Western Succession. The Mount Guide Quartzite yields MDAs of 1883 ± 7 Ma and 1842 ± 9 Ma, substantially older than previously reported from the northern inlier. Metasedimentary units intercalated with the Eastern Creek Volcanics yield contrasting MDAs of 1877 ± 8 Ma and 1766 ± 15 Ma, indicating stratigraphic and depositional heterogeneity. The Jayah Creek Metabasalt contains interbedded quartzite with an MDA of 1857 ± 5 Ma, whereas the overlying Timothy Creek Sandstone yields an MDA of 1781 ± 15 Ma, consistent with an angular unconformity. The Warrina Park Quartzite and associated volcaniclastic units yield MDAs at 1862 ± 9 Ma, 1812 ± 5 Ma and 1781 ± 10 Ma, and the Moondarra Siltstone yields an MDA of 1776 ± 6 Ma. The Kallala Quartzite yields MDAs of 1812 ± 8 Ma and 1850 ± 4 Ma, indicating it is unlikely to form part of the Pre-Barramundi basement. Detrital zircons are dominated by late Paleoproterozoic populations with minor Neoarchean contributions. Zircon εHf(t) values range mainly between −6.7 and +8.7 and cluster near CHUR, indicating derivation from variably depleted to enriched crustal reservoirs consistent with mixed mantle-derived and evolved crustal source components. The combined U-Pb and Hf isotopic evidence challenges existing stratigraphic correlations and supports sediment derivation from mixed reworked crustal and juvenile sources within a subduction-related active continental margin during the late Paleoproterozoic. These results require revision of regional stratigraphic models and provide new constraints on basin evolution and crustal growth in the southern North Australian Craton.

Geoscience Frontiers

Geoscience Frontiers

17

2588-9192

N/A

N/A

22