DETECTING PALEOLIMNOLOGICAL AND ENVIRONMENTAL CHANGES IN MODERN HYPERSALINE LAKES IN AUSTRALIA USING PALYNOLOGY

Hundreds of ephemeral, shallow hypersaline lakes exist throughout southern Western Australia and Victoria, Australia. Most have pHs ranging from 1.5 to 4.0, and precipitate halite and/or gypsum in siliciclastic-hosted sediments. Palynological data were obtained from seventy-six spot and shallow core samples (less than 3,000 years old) in an attempt to interpret paleolimnological and environmental changes in thirteen different lakes, but focused primarily on Lake Brown in Western Australia. Variable numbers of diverse and commonly well-preserved pollen, spores and non-marine algae dominate the palynological assemblages. Statistical cluster analysis of four paleoclimatically important families (Asteraceae, Chenopodiaceae, Myrtaceae, and Poaceae) yielded four palynomorph assemblages. Each assemblage is representative of the prevailing regional vegetation, namely hummock grasslands, open woodlands, closed woodlands, and open grasslands. Cluster analysis of nine types of dispersed organic matter produced three palynofacies assemblages (A-C) and six sub-assemblages (A.1-A.3, B.1-B.3). Palynofacies assemblages/sub-assemblages A.1, B.2 and C suggest maximum lake levels (flooding); A.3 and B.1 represent evapoconcentration; and A.2 and B.3 indicate desiccation. Palynological assemblages are independent of palynofacies assemblages because the former are dependent upon larger-scale climatic and anthropogenic factors (temperature change, drought, mining), whereas the latter are controlled mainly by localized weather patterns, such as flash flooding.