Georgina Virgo Facies archit. & geochem. corr. Tonian/Cryogenian Adelaide Rift Complex palaeoenviro.

Georgina M. Virgo presents 'Facies architecture and geochemical correlation of Tonian and Cryogenian palaeoenvironments across the Adelaide Rift Complex, South Australia' at the 2023 Adelaide Superbasin Mini-symposium.

Co-authors:
Georgina M. Virgo, Alan S. Collins, Morgan L. Blades, Darwinaji Subarkah, Kathryn J. Amos, Juraj Farkas

Abstract:
The Neoproterozoic (~1000 to 539 Ma) was one of the most dynamic eras in Earth history and is marked by significant tectonic, biological, atmospheric, and climatic events. These global shifts facilitated the development of distinct lithologies and isotope geochemical signatures that correspond to suite of depositional conditions, from warm shallow carbonate-rich seas to cold, ice-covered continents. The Adelaide Superbasin in South Australia, preserves thick successions of these Neoproterozoic sedimentary rocks, recording the temporal and spatial variability and distribution of environments through time. Here we present palaeoenvironmental interpretations using detailed sedimentological and geochemical data collected from multiple sites in the northern Flinders Ranges. Sedimentary logs totalled 8.36 km of stratigraphic thickness, with over 600 samples collected for geochemical analysis. Facies and sequence stratigraphic analyses reveal deposition in a carbonate platform setting for the preglacial succession, glaciomarine setting that represent glacial advance and retreat phases for the syn-glacial succession, the post-glacial succession is charactersied by widespread transgression to a slope to basinal setting following the Sturtian glaciation. Carbonate samples in the pre-glacal succession record a shift from semi-restricted dysoxic waters to a more restricted, continentally sourced setting. Samples from the post-glacial succession record a geochemical pivot to more open, oxic to suboxic conditions. Our multifaceted approach provides a comprehensive framework for the sedimentological and geochemical control on the temporal and spatial distribution of depositional environments during a critical and unique time in Earth’s past.

Biography:
Georgina completed her Bachelor of Science (Honours) at the University of Adelaide in 2017. She continued on to do a PhD at the same institution, focused on the sedimentology and geochemistry of Tonian–Cryogenian successions in the northern Flinders Ranges. This research is ongoing and involves the application of high-resolution sedimentary logging and sequence stratigraphy, complimented by elemental and isotopic geochemistry. Georgina is also working within the Tectonics and Earth Systems Research Group as an administrative officer, and has recently commenced a position as a technical officer supporting undergraduate teaching within the discipline of earth sciences at the University of Adelaide.