ACID HYPERSALINE LAKES IN SOUTHERN WESTERN AUSTRALIA: PRELIMINARY PALYNOLOGICAL INTERPRETATIONS

Modern acidic hypersaline lakes in southern Western Australia present a unique opportunity to integrate palynology with sedimentology, geochemistry and microbiology in order to understand the biogeochemistry of these unusual lakes. The acidic lakes are ephemeral, shallow, have pHs ranging from 1.5 to 4.0, and precipitate halite and/or gypsum in siliciclastic-hosted sediments. Hostile environments such as these lakes are not typically considered assumed to be good repositories of organic materials; hence very few palynological studies exist. We have examined palynomorphs and dispersed organic matter in shallow cores, spot samples, and halite crusts from 12 lakes. Recovered palynomorphs vary in diversity and abundance but are generally well preserved. They include pollen of herbs, shrubs and trees such as Asteraceae (daisy), Poaceae (grass), Chenopodiaceae (salt bush) and Myrtaceae (e.g., Eucalyptus), colonial green algae, and algal zygospores (Zygnemataceae). Preliminary interpretations suggest that certain palynomorph assemblages are indicative of more arid conditions and conversely others are prevalent during wetter periods. This is in agreement with sedimentological and geochemical evidence for the strong influence of flooding, evapo-concentration, desiccation and wind on the lakes.