AMS radiocarbon dating in the study of arid environments: Examples from Lake Eyre, South Australia

Sediments containing small amounts of carbon are difficult to date using traditional radiocarbon techniques. This has resulted in less than satisfactory attempts to establish reliable chronologies for sedimentation and environmental change in the Australian arid zone. We describe here the first application of the AMS technique to the radiocarbon dating of salt lake core samples, using a chemical pretreatment methodology based on pollen extraction techniques. These results indicate that fine-grained charcoal and pollen have a similar source and depositional mechanism. The data from Lake Eyre imply a last glacial maximum deposition for the major buried halite layer, an Early Holocene return to lacustrine conditions, with a Late Holocene reduction of net sediment inout to Madigan Gulf as the present playa conditions were established.