Comparing interglacials in eastern Australia: A multi-proxy investigation of a new sedimentary record

The Application of Pollen Radiocarbon Dating and Bayesian Age-Depth Modeling for Developing Robust Geochronological Frameworks of Wetland Archives

“…Previous studies examining sedimentary sequences extracted from these locations suggest that both records extend beyond the last glacial maximum (Black et al 2006;Cadd et al 2018;Lewis et al 2020;Forbes et al 2021), a rare occurrence in Australia (Cadd et al 2021). However, previous work from sedimentary records in these locations has identified major outliers in the 14 C chronologies (Lewis et al 2020;Forbes et al 2021), indicating the need for a more targeted approach to the development of 14 C chronologies for these important records. Lake Werri Berri is part of the Thirlmere Lakes system, approximately 40 km inland from the New South Wales south coast (Figure 1).…”

“…The Thirlmere Lake system comprises five presently ephemeral lakes within a late Tertiary abandoned river valley. The sediments of the Thirlmere Lakes display repeating sequences of organic clay, clay, and clayey sands overlain by up to 4 m of Holocene, organic-rich lacustrine and palustrine sediments (Black et al 2006;Forbes et al 2021). See Supplementary Information for further coring and sedimentological details.…”

“…Blanks processed using this method produce consistent, low F 14 C values, providing confidence that robust, finite ages <50,000 years can be achieved on pollen concentrate samples. The background measurements from the pollen samples extracted from >110,000 year old peat sediments from the Thirlmere Lakes (Forbes et al 2021) using this method have yielded F 14 C values of 0.00318± 0.00007 (weighted average, n=18; including the Lake Werri Berri and Welsby Lagoon batches).…”

“…Here we report on a method of rapid batch-processing for the isolation of pollen concentrates using a combination of filtration and floatation used at the Chronos 14-Carbon Cycling Facility at the University of New South Wales. We test the applicability of this pollen extraction procedure and subsequent 14 C dating from two important palaeoenvironmental archives in eastern Australia that have previously been identified as difficult to date with 14 C methods (Forbes et al 2021;Lewis et al 2020). 14 C ages previously obtained from bulk sediment, plant remains and charcoal from sediment sequences from the Thirlmere Lakes and Welsby Lagoon have exhibited substantial scatter and stratigraphic inversions.…”

RADIOCARBON PROTOCOLS AND FIRST INTERCOMPARISON RESULTS FROM THE CHRONOS 14CARBON-CYCLE FACILITY, UNIVERSITY OF NEW SOUTH WALES, SYDNEY, AUSTRALIA

“…h Forbes et al (2021). i Unpublished site but preliminary work suggests correlation to Forest Bed at West Point, Falkland Islands (Macphail and Cantrill 2006).…”