Optical dating of an aeolian deposit on the Murrumbidgee floodplain

Optical dating of quartz grains from an aeolian deposit using multiple aliq uot additive-dose and regenerative-dose growth curves, combined using the A ustralian slide method, produced ages slightly exceeding the C-14 2 sigma a ge range of 3470-4230 yr from charcoal fragments from the same horizon. A s lightly greater degree of scatter was observed about the additive-dose grow th curve than about the regenerative-dose growth curve, raising the possibi lity that the sample might have been composed of grains containing differen t palaeodose (P) as a result of incomplete predepositional bleaching. This possibility was first investigated using small aliquots ( similar to 10 gra ins) and a single-aliquot regenerative-dose (SAR) protocol. Asymmetric P di stributions were observed, initially interpreted as supporting the presence of a partially bleached population. Single grains of quartz were then exam ined to determine if several discrete P populations could be resolved, ther eby providing information on reworking events, and larger aliquots were the n measured in an attempt to reconcile the "Australian slide" findings with the small aliquot and single-grain results. (C) 2000 Elsevier Science Ltd. All rights reserved.