Late Quaternary evolution of Robe Range, southeast South Australia: An archive of deposition and destruction of a coastal barrier complex

Southeast South Australia is a unique geomorphological province, preserving geographically extensive Quaternary coastal barrier successions that have formed since approximately 1 Ma. This region is considered a natural laboratory for reconstructing glacio-eustatic sea-level changes due to its far-field location remote from the former Northern Hemisphere ice sheets and a relatively high level of tectonic stability. More importantly, a consistent rate of epeirogenic uplift within this region provides an opportunity to document a record of the long-term coastal barrier evolution and its associated palaeosea-levels. Robe Range, the seaward-most onshore coastal barrier associated with Marine Isotope Stage (MIS) 5 interstadials, is currently undergoing rapid coastal erosion since the culmination of Holocene post-glacial relative sea-level rise some 7000 years ago. The erosion has revealed a complex geological record with respect to the history of coastal barrier deposition determined from extensive outcrops of calcarenites of the Late Pleistocene Bridgewater Formation. In addition, the coastal retreat provides insights into sediment reworking and the ultimate preservation potential of the marginal marine succession. The first objective of this thesis is to provide a reconstruction of sedimentary facies and a geochronological framework for the depositional phases of the Robe Range coastal barrier based on amino acid racemisation (AAR), optically stimulated luminescence (OSL) and radiocarbon methods. This includes a re-evaluation of the lateral distribution and age of flint conglomerate units representing MIS 5c sea-level proxy proposed by previous studies. The second objective is to understand the impact of ongoing coastal erosion on the Robe Range coastal barrier, particularly in describing erosional rocky coast landforms and determining the proportion of reworked skeletal carbonate sediments within modern beaches based on large datasets of amino acid racemisation dating of single-foraminifers of the species Lamellodiscorbis dimidiatus.