Long-distance sand transport to the temperate basalt plains of southeastern Australia: implications for atmospheric circulation just prior to the last glacial maximum

The Western Victorian Volcanic Plains of southeastern Australia is the third largest basalt province in the world. Whilst the climate of this region is presently temperate, it lies east and south of extensive dunefields which were active during more arid phases in the past.

While investigating the timing of fossil deposition at the Spring Creek megafaunal site – a locality initially argued to provide evidence for last glacial survival of extinct invertebrate taxa – we discovered a surprising quantity of sand-sized quartz within the clayey sediments of the deposit. Since quartz sand is not common in the Western Victorian basalt province or within underlying Tertiary marls, we propose this sand to be allochthonous and transported some distance. The quartz sand yields a particularly bright luminescence signal characteristic (although not diagnostic) of aeolian quartz from dune sediments to the west, and dates using single-grain optically stimulated luminescence to just prior to the Last Glacial Maximum.

In this study we investigate the potential for long-distance sand transport to the Spring Creek site on the Western Victorian basalt plains, by means of climate reanalysis and wind regime modelling for the LGM compared with the present-day time slices. We find that LGM wind regimes were dominated by strong, unidirectional westerly air flow at Spring Creek, compared with more variable and weaker wind orientations and velocities in the present day. Our results suggest stronger potential for eastward distal sand transport from the dunefields west of the basalt plains during the LGM. This enhanced wind strength and transport was coeval with enhanced aeolian activity in those dunefields, and with reactivation of sandy palaeoshorelines just to the south of them. Additional modelling of LGM wind vectors compared with aeolian accumulation onto securely dated transverse shoreline dunes of the same age in the Willandra Lakes to the north supports our findings, by indicating an intensification of westerly winds over the southeastern part of the Australian continent just prior to the LGM.