Age and geochemistry of the Boucaut Volcanics in the Neoproterozoic Adelaide Rift Complex, South Australia
Australian Journal of Earth Sciences
The Adelaide Rift Complex in South Australia records the break-up of Rodinia at a time of great climatic and biological evolution. The Boucaut Volcanics within the Neoproterozoic Adelaide Rift Complex of the Adelaide Superbasin lie at the base of the Burra Group, marking the boundary between the Burra Group and underlying Callanna Group. Despite their significance as one of the few volcanic units within the rift complex, there has been no robust age determination published for the Boucaut Volcanics. We use U–Pb zircon LA-ICP-MS data to determine an age of 788 ± 6 Ma for the eruption of the bimodal Boucaut Volcanics. This has important implications for constraining the timing of stratigraphy within the Adelaide Superbasin. This also has far-reaching implications for plate tectonic reconstructions of Australia and Laurentia, and for correlating global isotope anomalies for the Neoproterozoic.KEY POINTS New U–Pb zircon data provide a revised age for the Boucaut Volcanics of 788 ± 6 Ma. Whole-rock geochemistry data highlight the bimodality of the Boucaut Volcanics, with both mafic and felsic components present. Boucaut Volcanics potentially correlate with units in the southwest United States, which would support an AUSWUS plate tectonic configuration during the Neoproterozoic.
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