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The Coorong Coastal Plain in southeastern South Australia preserves a long Quaternary record of cool-water, temperate-carbonate sedimentation in the form of high wave energy, barrier shoreline deposits and associated back-barrier lagoon facies that formed during successive sea-level highstands. Whole-rock samples of bioclastic skeletal carbonate sand with subordinate quartz were collected from aeolian facies (modern and relict foredunes) of a Holocene embayment fill and from ten Pleistocene barriers across the coastal plain in a transect from Robe to Naracoorte. The extent of leucine racemization (total acid hydrolysate and free amino acids) in the Pleistocene skeletal carbonate sand (63–500 μm) increases monotonically with age and is consistently higher than for entire fossil molluscs from the same allostratigraphic units, reflecting the lengthy residence time for bioclasts in this high wave energy environment, and sediment recycling from the erosion of older barriers. The extent of racemization in the whole-rock samples conforms with a model of apparent parabolic racemization kinetics and the calculated ages largely agree with previously determined luminescence ages. Apart from a possible reinterpretation of the significance of the West Naracoorte Range, the coastal plain succession indicates that interglacial sea levels did not deviate by more than 6 m of present sea level for the Mid- and Late Pleistocene thus providing an important framework for quantifying ice volume during sea-level highstands and calibrating the oxygen isotope record.

Surficial sediments of Gulf St. Vincent, South Australia, are predominantly bioclastic, cool-temperate carbonates. Benthic foraminifera are abundant and distribution of species is closely related to water depth. For example, Massilina milletti is most common at depths ca. 40 m, while Discorbis dimidiatus is characteristics of shallow, subtidal environments. Elphidium crispum, a shallow-water species, and E. macelliforme, favoring deeper water, provide a useful numerical ratio. Their logarithmic relative abundance, in the sediment size fraction 0.50–0.25 mm, correlates strongly with water depth. Vibrocores SV 4 and SV 5 recovered undisturbed sections of Quaternary strata from the deepest part (ca. 40 m) of Gulf St. Vincent. Amino acid racemization and radiocarbon age determinations show that late Pleistocene sections of the cores were deposited over the time ca. 45,000 to 30,000 yr B.P. Species of fossil foraminifera, recovered from these sections, are mostly extant in modern Gulf St. Vincent, thus allowing paleoecological inferences of late Pleistocene sea levels. These inferred sea-level maxima can be correlated with those determined from study of Huon Peninsula coral reef terraces. Initial estimates of tectonically corrected sea levels for transgressions in Gulf St. Vincent at 40,000 and 31,000 yr B.P. are −22.5 m and −22 m, respectively. The intervening regression lowered sea level to −28 m.

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