Late Pleistocene interstadial sea-levels (MIS 5a) in Gulf St Vincent, southern Australia, constrained by amino acid racemization dating of the benthic foraminifer Elphidium macelliforme

• Published in: Quaternary Science Reviews
• Main Authors: Murray-Wallace, C.V., Cann, J.H., Yokoyama, Y., Nicholas, W.A., Lachlan, T.J., Pan, T.Y., Dosseto, A., Belperio, A.P., Gostin, V.A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2021
• Subjects: Late Pleistocene sea levels; interstadial; Amino acid racemization; foraminifers; Southern Australia; ice core
• Online Access: http://hdl.handle.net/2440/130532; https://doi.org/10.1016/j.quascirev.2021.106899

In contrast to the detection and resolution of Late Pleistocene interstadials (Marine Isotope Stages; MIS 5c, 5a and 3) in marine and ice core-based oxygen isotope records, accurately defining palaeosea-levels for these events from sea level indicators remains a challenge. Commonly, such investigations have been undertaken in tectonically active, subduction-related settings, on emergent marginal marine-coastal successions above present sea level, given that the higher ice volumes during these Marine Isotope Stages resulted in ice-equivalent sea levels significantly below present, particularly in far-field settings. Delineation of palaeosea-levels for this period, has accordingly involved an assumption about the long-term rate of coastal uplift. Core SV#23 collected from the tectonically highly stable, remote far-field setting of southern Gulf St Vincent, southern Australia, in a present water depth of 40 m obtained a 3.89 m undisturbed sedimentary record of Late Pleistocene to Holocene age. The basal 2.39 m of the sediment record is of Late Pleistocene interstadial age, as it overlies the Last Interglacial Glanville Formation (128–118 ka; MIS 5e) and occurs beneath the Holocene St Kilda Formation. The extent of aspartic acid and glutamic acid racemization in the benthic foraminifer Elphidium macelliforme sampled at 2 cm intervals continuously from the interstadial succession in Core SV#23, confirms the relative age interpreted from lithostratigraphy. A mean amino acid racemization (AAR) age of 75 ± 13 ka indicates a correlation with MIS 5a, and highlights the utility of E. macelliforme as a species for AAR geochronology. As the foraminifers more closely define the timing of sedimentation, the interstadial succession is regarded as beyond the range of radiocarbon dating (>50 kyr), as revealed in a comparison of radiocarbon ages of fossil molluscs with AAR ages for E. macelliforme from the same depth intervals within the interstadial succession. All of the radiocarbon ages for fossil marine molluscs from the ...