The role of the Australian Monsoon in the western catchment of Lake Eyre, central Australia, during the Last Interglacial

Relative changes in monsoon intensity can be deduced from palaeoenvironment al data such as lake level records, shore line features and aeolian/loess d eflationary sequences. These data can provide assessments of past changes i n the nature and timing of monsoon activity. The Lake Eyre basin (1,300,000 km(2)), in central Australia, is a key site for determining the nature and extent of monsoon fluctuations through glacial/interglacial cycles. A last interglacial high lake-level phase some time between 90-130 ka is confirme d by both palaeoenvironmental and computer simulated data. This coincides w ith a time of high sea level and strong orbital forcing of the Asian monsoo n, the primary forcing mechanism for the north Australian monsoon. The larg e monsoon-fed river systems of the Cooper and Diamantina are likely to have contributed most of the inflow to fill this 'megalake' phase of Lake Eyre. Evidence from the Neales River suggests that these smaller and more southe rly rivers were also active. This paper examines the likelihood that the re lative synchroneity in fluvial and lacustrine activity across the basin at this time is the result of a common climate forcing mechanism. In examining the role of the monsoon in this western catchment of the lake we present t wo possible scenarios to explain enhanced fluvial activity during the last interglacial. (C) 1999 INQUA/Elsevier Science Ltd. All rights reserved.