Biological and sedimentary facies of Australian salt lakes
Abstract Four main types of salt lakes are recognized in Australian: (1) large playa lakes, (2) small closed lakes, or pans, (3) crater lakes, and (4) coastal lakes (not connected to the sea). Basically all have an NaCl chemistry. Biological and sedimentary facies characteristic of these salt lakes can be arranged into three basic groups which relate to particular phases in lake regimes. These phases are: (1) wet phases of ephemeral shallow lakes, (2) dry lakes, and (3) deep water lakes. All elements of the salt lake biota with fossilizable remains are discussed, with a detailed account of the (palaeo)ecological information they offer. Elements of the nonaquatic biota associated with salt lake sediments are also analysed. Sedimentary features of Australian salt lakes pertinent to palaeoecology are discussed in the context of their association with the biota, using numerous illustrations. The distribution of the biota on lake floors, for example, its concentration in particular areas of the lake, or its destruction during particular episodes such as lake filling and drying, is mentioned in the context of recognizing different facies. Three major lake regime phases are presented with emphasis on the biological and sedimentary facies which characterize them. The paper concludes with a brief discussion of the relevance of recognizing particular salt lake facies and changes in lake histories for the study of palaeoclimates and for mineral and oil exploration.