The last interglacial shoreline in southern Australia: Morphostratigraphic variations in a temperate carbonate setting

• Published in: Quaternary international 1995, Vol.26, p.7-19
• Main Authors: Belperio, A.P., Murray-Wallace, C.V., Cann, J.H.
• Format: Article
• Language: English
• ISSN: 1040-6182; 1873-4553
• DOI: 10.1016/1040-6182(94)00041-3

Coastal marine strata of last interglacial age are preserved extensively around the southern Australian coastline. The sedimentary facies have many features in common with adjacent Holocene coastal facies and contemporary peritidal environments, but are partly lithified, mostly elevated, and laterally displaced inland. Sediments are dominantly biogenic skeletal carbonates of cool-temperate water affinities (foram-mollusc-coralline alga association). Surficial calcrete development has aided preservation of morphostratigraphic forms and sedimentary structures. Large coastal barrier complexes comprising aeolian dune, foredune and back-barrier lagoon facies characterize exposed coastal tracts facing the Southern Ocean. In contrast, broad, low-gradient peritidal complexes, with a shoaling-upward sequence of subtidal, intertidal, and supratidal mud/sand flat facies, characterize protected shorelines of major gulfs and embayments. A similar upward-shoaling sequence is preserved in back-barrier lagoons. Along the more tectonically stable part of southern Australia, the last interglacial palaeo shoreline is consistently recorded at 2 m above present sea level. This is an important regional datum that is significantly below the +6 m level globally attributed to this sea level highstand. Elsewhere, neotectonic variations in shoreline elevation are clearly discernible with uplift of up to 18 m associated with Quaternary volcanism near Mount Gambier. The last interglacial strata contain a number of fossils with tropical affinities that no longer live in the local waters. The presence of these fossils is consistent with warmer coastal waters during the last interglaciation, but does not necessarily imply warmer oceanic waters or a warmer continental climate.