Aeolian–fluvial interaction and climate change: source-bordering dune development over the past ∼100 ka on Cooper Creek, central Australia

Abstract

This study provides an interpretation of interrelated Quaternary fluvial and aeolian activity related to climate change on Cooper Creek in the Lake Eyre Basin in southwestern Queensland, central Australia. The extensive muddy floodplain is characterised by buried sandy palaeochannels now almost entirely invisible but stratigraphically connected to source-bordering dunes that emerge as distinctive sandy islands through the floodplain surface. Luminescence dating has identified pronounced periods of fluvial activity represented by abundant sandy alluvium from Marine Isotope Stages (MIS) 8–3. While all these sandy fluvial episodes on Cooper Creek were much more powerful than anything subsequent, they appear to be ranked in order of declining activity. MIS 8–6 saw reworking of almost the entire floodplain whereas subsequent phases of reworking were far less extensive. Source-bordering dunes were derived from active sandy channels in late MIS 5 (∼85–80ka) and mid MIS 3 (50–40ka). After ∼40ka sand-channel activity largely ceased and the floodplains and channels were inundated with mud, isolating the dunes as emergent features. Although aeolian reworking of the upper parts of some dunes has continued to the present, they show remarkable resilience, having survived without appreciable migration for at least 40ka. Whilst the channels once determined the location of source-bordering dunes, in an interesting role reversal the remnant dunes now determine the position of many contemporary flood-channels and waterholes by deflection and confinement of overbank flows.