Testing the potential of a transferred IRSL (T-IRSL) feldspar signal for luminescence dating

摘要

One of the major dilemmas in feldspar luminescence dating is that the infra-red stimulated luminescence (IRSL) signals are either stable and difficult to bleach when measured at elevated temperatures, or unstable and easy to bleach when measured at low temperatures. To identify a signal for sediment dating that is both stable and easy to bleach, we investigate the potential of an optically and thermally transferred IRSL (TARSI.) signal. Based on the mechanisms described in Wang et al. (2014), we develop a T-IRSL single-aliquot regenerative-dose (SAR) measurement protocol. We investigate the a-thermal stability of six different T-IRSL signals from a sample of infinite age using fading experiments, and by comparing field and laboratory saturation levels. The T-IRSL signal measured at 125 degrees C (T-IRSL125) following a preheat of 280 degrees C, is found to be as stable as the post-IR IRSL 290 degrees C signal (pIRIR(290)). Furthermore, laboratory bleaching experiments show that the T-IRSL125 signal bleaches faster than the pIRIR(290) signal, and that the corresponding residual doses are more than 40% lower. This indicates that T-IRSL signals may be superior to pIRIR methods for dating young and/or insufficiently bleached deposits. However, a SAR protocol performance test of the T-IRSL125 signal yielded a systematic underestimation of 8 +/- 2%. This is possibly caused by a sensitivity change during the first preheat and requires further investigation. (C) 2015 Elsevier Ltd. All rights reserved.