Provenancing dryland sediments recovered from the marine realm to reconstruct Late Quaternary Australian climate variability

We geochemically-fingerprinted a large set of sediments collected from potential source areas (PSAs) in southeastern and southcentral Australia and to compare these data with the record obtained from X-ray Fluorescence (XRF) scanning on a long deep-sea sediment core MD03-2607 obtained offshore Kangaroo Island, South Australia. The entire data set of samples collected on land as well as the downcore measurements were unmixed using the numerical end-member method AnalySize. In this approach, we successfully use the elements Al, Fe, K, Mn, S, Sr and Y to define end members. In addition, the on-land occurrences of the chemical ratios of Zr/Zn, Ti/Rb, Ti/Y and Zr/Rb are used to support the provenance of the chemical end-members. Three main PSA’s are defined: Murray River Basin (MRB), Darling River Basin (DRB) and Kati Thanda – Lake Eyre District (LED), of which the MRB is represented in two different chemical end members. The downcore contributions of these end members in the sediment core are consequently interpreted in terms of fluvial (MRB and DRB) versus aeolian (LED) input.  Consequently, the downcore dominance of sediment-transport modes are interpreted in terms of river runoff versus aeolian input over the last 125 kyr. The downcore palaeoclimate proxies show a dominance of MRB during the interglacial intervals versus a dominance of both LED (dust) and DRB input during the glacial ones, suggesting increased seasonal contrasts during glacial austral winter. See: www.nioz.nl/dust