Last modified: 2011-08-16
Abstract
Lake Cowan is an acidic hypersaline lake located 207 km north of Esperance, Western Australia. Its ephemeral nature is characterized by four stages including flooding, desiccation, evapoconcentration and eolian erosion and deposition, making it a highly dynamic lake system. As part of a 2009 drilling expedition to several sites in the region, three cores were drilled in this area. CB1-09 (total depth of 6.58 meters) was drilled on the shore of the lake next to the Coolgardie-Esperance Highway, north of Norseman, and LA1-09 (21.63 meters) and LA2-09 (59.64 meters) were situated in a small marginal lake called Lake Aerodrome, south-west of Norseman.
This study focuses on the analysis of the palynological contents of the Neogene interval in these cores (which includes all of CB1-09 and LA1-09 and only 0 to 33.11 meters in LA2-09). The uppermost sediments reflect the local flora and are dominated by Poaceae, Myrtaceae, Chenopodiaceae, Asteraceae and Casuarinaceae. Fabaceae, and Acacia are also present throughout the cores. The abundances of pollen families vary greatly from one core to the other. Clumps of pollen belonging to Poaceae, Myrtaceae and Fabaceae are common, suggesting short transport distance into the basin in more recent time. Overall, pollen abundances and diversity decrease with depth. Although climate and regional geology have affected the evolution of the lake, it appears that local factors, such as lake dynamics and nearby vegetation, have a much stronger influence on the pollen record.