Coastal aminostratigraphy of the last interglaciation in Southern Australia

Abstract

Amino acid racemization data for marine molluscs of the last interglaciation from southern Australia provide the basis for a predictive model for relative dating of late Quaternary sequences. Genera analyzed include Anadara sp., Katelysia sp., Glycymeris sp., and Fulvia sp. that exhibit moderate racemization rates. A genus effect on racemization is not evident in these taxa. Coefficients of variation for intershell D L ratio variation for each deposit are generally less than 12%. The extent of racemization in molluscan fossils of the last interglaciation from temperate coastal settings in southern Australia represents an exponential function of temperature and is in general accord with data from Northern Hemisphere sites with similar contemporary mean annual temperature values. These data highlight the potential of amino acid racemization for global correlation programs. The amino acid data from southern Australia suggest, however, that a larger margin of variation may have to be accounted for in stratigraphic correlation, as indicated by the greater scatter of data around the oxygen isotope substage 5 e isochron. These data have implications regarding the age-resolving power of amino acid racemization.