Late Quaternary evolution of Lake Urana, New South Wales, Australia

Abstract

Lake Urana is a well-preserved relict lake in the semi-arid Riverine Plain of southeastern Australia. A compound lunette at its eastern shoreline consists of a quartz-sanddominated unit (Bimbadeen Formation), thermoluminescence (TL) dated at 30 ka to 12 ka, and a clay and sand facies unit (Coonong Formation), dated at 55 ka to 35 ka. The intervening period indicates a phase of periodically exposed lake floor and soil formation. The older wet phase conforms well with similar environments recorded from the same period at Lake Mungo. However, the return to high water levels from 30 ka to 12 ka departs sharply from the generally accepted palaeoclimatic model from Australia, which demands severe glacial maximum desiccation and widespread construction of clay lunettes. Although hydrological budgets calculated for Lake Urana and nearby Lake Cullivel require high glacial maximum water levels they do not support higher precipitation.

Climatic records over the past 30 ka from temperate Australia – a synthesis from the Oz-INTIMATE workgroup

“…7a). High lake levels and increased fluvial activity in the southern MDB indicate relatively wet conditions, possibly due to seasonal snowmelt runoff in the river headlands (Bowler, 1978;Page et al, 1994;Hamilton, 2006;Page et al, 2009;Kemp and Rhodes, 2010).…”

“…The Lake Keilambete record suggests generally high lake levels at the same time, although this is only constrained by two conventional radiocarbon dates (Bowler and Hamada, 1971) and warrants further investigation. Large channels developed on all rivers feeding the the Lachlan, Murrumbidgee, Murray and Goulburn Rivers (collectively the Riverine Plains) (Bowler, 1978;Page et al, 1994;Hamilton, 2006;Page et al, 2009;Kemp and Rhodes, 2010). The large palaeochannels preserved in the MDB and dated at 35 to 25 ka (the Gum Creek Phase) and are interpreted to reflect high rates of lateral channel activity, driven by high sediment loads derived from denuded and destabilised headwater catchments leading up to the coldest period during the LGM Page et al, 2001).…”

“…On the Riverine Plains, lakes fed by the major river systems were deep or overflowing (Page et al, 1994) and records from the Willandra Lakes suggest a period of high lake levels at Lakes Mungo and Arumpo just prior to 30 ka, followed by oscillating lake levels persisting after this time and throughout the LGM (Bowler, 1998;Bowler et al, 2003;McIntosh and Barrows, 2011;Bowler et al, 2012). This fluvio-lacustrine activity has been argued to represent increased runoff within the catchments in response to increased snow melt in the highland headwaters, combined with reduced vegetation cover (Kemp and Rhodes 2010).…”

Wind v water: Glacial maximum records from the Willandra Lakes

“…Basins close to uplands, regions of most available water, or supplied by major rivers remained full even under conditions of glacial maximum aridity. As examples, the lake basins of Urana (Page et al 1994), Kanyapella on the Murray River (Bowler 1967(Bowler , 1978 and Nekeeya near the Grampians (Bowler 1999) all remained at high levels during the glacial maximum due entirely to the efficient nature of the catchments which supplied them. Similarly, glacially wet conditions pertained in glacial age catchments in the Flinders Ranges (Williams et al 2001).…”

Peopled Landscapes: Archaeological and Biogeographic Approaches to Landscapes

“…Basins close to uplands, regions of most available water, or supplied by major rivers remained full even under conditions of glacial maximum aridity. As examples, the lake basins of Urana (Page et al 1994), Kanyapella on the Murray River (Bowler 1967(Bowler , 1978 and Nekeeya near the Grampians (Bowler 1999) all remained at high levels during the glacial maximum due entirely to the efficient nature of the catchments which supplied them. Similarly, glacially wet conditions pertained in glacial age catchments in the Flinders Ranges .…”