Underestimation of equivalent dose in single-aliquot optical dating of feldspars caused by preheating

The ability of single-aliquot techniques to recover a known Laboratory dose in coarse-grain potassium-rich feldspar separates is tested. It is shown t hat, for the samples under study, single-aliquot methods underestimate the known dose. It is deduced that this phenomenon is caused by an increase in electron trapping probability as a consequence of heating. The same phenome non would lead to an underestimation in the equivalent dose in a natural sa mple. Multiple-aliquot techniques for equivalent dose determination may not suffer from this problem, but are not suitable for samples that might not have been completely bleached at the time, of deposition. it is argued that testing for changes in electron trapping probability should become routine practice in the single-aliquot dating of feldspar. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.