Age and geochemistry of the Boucaut Volcanics in the Neoproterozoic Adelaide Rift Complex, South Australia

Abstract

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

1. New U–Pb zircon data provide a revised age for the Boucaut Volcanics of 788 ± 6 Ma.

2. Whole-rock geochemistry data highlight the bimodality of the Boucaut Volcanics, with both mafic and felsic components present.

3. Boucaut Volcanics potentially correlate with units in the southwest United States, which would support an AUSWUS plate tectonic configuration during the Neoproterozoic.

Keywords:

• Adelaide Rift Complex
• Flinders Ranges
• geochemistry
• geochronology
• Neoproterozoic
• Rodinia
• Snowball Earth
• Adelaide Superbasin

Acknowledgements

Jarred Lloyd and Claire Wade are thanked for providing regional overview data and context. A. S. Collins acknowledges the MinEx CRC, and his contribution forms MinEx CRC output #2020/46. Sarah Gilbert and Ben Wade at Adelaide Microscopy are thanked for help obtaining analytical data. Wolfgang Preiss and an anonymous reviewer are thanked for reviews, their feedback greatly improved this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data that support the findings of this study are openly available in Figshare at https://doi.org/10.6084/m9.figshare.13110500.v1