The age of the Pooraka formation and its implications, with some preliminary results from luminescence dating

Abstract

Stratigraphic relationships, supported by luminescence dating, suggest that the Pooraka Formation spans a far greater time interval than previously recognised on the basis of radiocarbon dating and stratigraphic analysis of discrete sedimentary sections. It extends back as far as the Last Interglacial. Re-evaluation of the radiocarbon ages that indicate an interstadial age (i.e. Oxygen Isotope Stage 3; 45 to 30 ka BP) for the sediments is required. Alternatively, a considerable time interval for deposition of the Pooraka Formation would necessitate that the unit be diachronous across the landscape. An age extending back to the Last Interglacial (Oxygen Isotope Substage 5c; c. 125 ka BP) would provide the appropriate palaeo-climates and palaeo-environments for fluvial sedimentation. The revised age has implications for landscape evolution, archaeological and palaeomagnetic prospecting as well as the antiquity of the Diprotodon in the Adelaide area.