Paper II: The interpretation of measurement-time-dependent single-aliquot equivalent-dose estimates using predictions from a simple empirical model

Narrow spectrum (blue-green) laboratory partial bleaching of aliquots of natural sedimentary quartz has been shown to have a significant effect on equivalent dose (measured using a single aliquot procedure) calculated as a function of measurement time (De(t)). A simple model, based on empirical data, is presented in which the effects of partial bleaching on De(t) are predicted, taking into account the influences of pre- and post-burial doses. The model is applied to the case of heterogeneous populations of partially bleached single grains with various ranges of residual doses. Modelling shows that under realistic conditions, De histogram plots are unable to distinguish between samples having age overestimates and those with correct ages, whereas the proposed De–Z plot is able to make this distinction. Furthermore, modelling shows that De–Z plots can identify sub-populations of grains/aliquots that show most evidence of full bleaching, which can then be used to estimate a correct mean De value.