Optical dating of an Eemian site in Northern Russia using K-feldspar

Some published studies present evidence that quartz OSL dating of low (∼ 1 - 2 Gy / ka) dose rate material may underestimate the true age of a deposit by ∼ 10 - 15 % at ∼ 130 ka or for D_e values of ∼ 150 - 200 Gy. It is well known that feldspar IRSL grows to much higher doses than quartz and thus has the potential of performing better in this age range. In this paper we report on our continuing testing of the accuracy of K-feldspar IRSL dating with anomalous fading correction on known-age Eemian (∼ 125 - 130 ka) material from northern Russia. Using a SAR IRSL protocol the luminescence characteristics of our samples are first documented and D_e values and fading rates (g values) measured. A single site-averaged fading rate of 3.26 ± 0.09 % / decade (n = 80) is obtained and this value used to correct the optical ages. We compare the fading corrected IRSL ages with the known age of the deposits and with the results from a similar study on known-age Eemian material in Denmark. Finally, we discuss which dosimeter (K-feldspar or quartz) is preferred for this type of material.