Whole-rock aminostratigraphy of the Coorong Coastal Plain, South Australia: towards a 1 million year record of sea-level highstands

Abstract

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.

Pleistocene raised marine terraces of the Spanish Mediterranean and Atlantic coasts: records of coastal uplift, sea-level highstands and climate changes

“…The palaeo-position of sea level is also debated. Values of 17 m asl have been proposed by Murray-Wallace et al (2001) in the stable South Australia, and by Hearty et al (1999) in the Bahamas. The presence of a warmer fauna in deposits of OIS 11 was described in Chile in a dramatically exposed sequence of raised Pleistocene marine terraces (Ortlieb et al, 1996).…”

Application of sedimentary and chronological analyses to refine the depositional context of a Late Pleistocene vertebrate deposit, Naracoorte, South Australia

“…Overlying the Gambier limestone is a sequence of 13 sub-parallel stranded Pleistocene beach dune facies, distributed across south eastern South Australia from Naracoorte to the coast at Robe (Sprigg, 1952;Murray-Wallace et al, 2001). These ridges are composed of bioclastic, calcareous carbonates of the Bridgewater formation (Belperio, 1995).…”

“…These ridges are composed of bioclastic, calcareous carbonates of the Bridgewater formation (Belperio, 1995). The NCWHA cave system underlies the easternmost of these dunes, the Naracoorte East Ridge which may be as old as 935 ± 178 ka (Murray-Wallace et al, 2001). …”

Bayesian age-depth modelling of Late Quaternary deposits from Wet and Blanche Caves, Naracoorte, South Australia: A framework for comparative faunal analyses

“…Overlying the Gambier Limestone is a series of stranded Pleistocene beach dune facies known as the Bridgewater Formation. The oldest of these is the East Naracoorte Ridge, dated by whole-rock amino acid racemisation to 935±178 ka (Murray-Wallace et al 2001) and overlies the Naracoorte Caves. All known caves in the region are registered with the Australian Karst Index (Matthews, 1985) and are identified by unique cave numbers (e.g., 5U10, 11).…”