Luminescence isochron dating: A new approach using different grain sizes

A new approach to isochron dating is described using different sizes of quartz and K-feldspar grains. The technique can be applied to sites with time-dependent external dose rates. It is assumed that any underestimation of the equivalent dose (D-e) using K-feldspar is by a factor F, which is independent of grain size (90-350 mum) for a given sample. Calibration of the beta source for different grain sizes is discussed, and then the sample ages are calculated using the differences between quartz and K-feldspar D-e from grains of similar size. Two aeolian sediment samples from north-eastern China are used to illustrate the application of the new method. It is confirmed that the observed values of D-e derived Using K-feldspar underestimate the expected doses (based on the quartz D-e) but, nevertheless. these K-feldspar D-e values correlate linearly with the calculated internal dose rate contribution, supporting the assumption that the underestimation factor F is independent of grain size. The isochron ages are also compared with the results obtained using quartz D-e and the measured external dose rates.