A modified multi-elevated-temperature post-IR IRSL protocol for dating Holocene sediments using K-feldspar

A modified multi-elevated-temperature post-IR infra-red stimulated luminescence (MET-pIRIR) protocol is proposed for dating young samples of Holocene age using K-feldspar. The protocol utilizes a five-step MET-pIRIR measurement with a moderate preheating of 200 degrees C for 60 s, and a narrow IR stimulation temperature increment of 30 degrees C (i.e., the five measurement temperatures are 50, 80, 110, 140 and 170 degrees C). Using this method, the residual doses of the MET-pIRIR signals are generally less than 1 Gy. Holocene aeolian samples from Northern China were tested using the 30 degrees C-increment modified MET-pIRIR method. The results demonstrate that similar ages from 140 degrees C to 170 degrees C were obtained for our samples, which were consistent with the quartz optically stimulated luminescence (OSL) ages. Based on this observation, the measurement procedures are further simplified to a three-step pIRIR protocol. The first IR stimulation at elevated temperature (110 degrees C) is used to remove the fading affected signals. This is followed by two steps of IR stimulation at high temperatures (140 and 170 degrees C) for equivalent dose (De) measurement. Dating results consistent with the expected ages have been obtained at stimulation temperatures of 140 and 170 degrees C. It is suggested that the first IR stimulation can effectively remove the fading component. The three-step pIRIR method has minimized the experimental procedures, while keeping the age plateau test. (C) 2013 Elsevier B.V. All rights reserved.