Zhang, Junjie , Tsukamoto, Sumiko , Long, Hao
2023-09-01 QUATERNARY GEOCHRONOLOGY 2023 78(卷), null(期), (null页)
The post-infrared infrared stimulated luminescence (post-IR IRSL; pIRIR) of feldspar, measured at an elevated temperature (e.g., 290 & DEG;C) following an initial IRSL measurement at 50 & DEG;C, has demonstrated minimal to no fading. However, these higher temperature pIRIR signals are less easily to reset by sunlight. A pulsed pIRIR signal measured at a relatively low temperature (e.g., 150, 225 & DEG;C) might be a good candidate as a non-fading and easily bleachable signal. Here, we test the potential of the pulsed pIRIR225 signal (100 & mu;s on-time and 400 & mu;s off time) for dating both fine-grained (FG) polymineral samples and coarse-grained (CG) K-feldspar samples from the Chinese Loess Plateau. For FG polymineral samples, the measured fading rates (g-value) of the off-time (201-500 & mu;s) pIRIR225 signal are only 0.5-1.1%/decade, but the equivalent dose (De) is significantly underestimated compared to the expected De of each sample, which ranges from 118 to 1360 Gy. For CG K-feldspar samples, the measured g-values of off-time pIRIR225 signal are 1.2-1.4%/decade, while the measured De values are consistent with the expected De values up to 530 Gy. Bleachability tests indicate that the pulsed pIRIR225 signal exhibits a similar bleaching rate as the continuous wave pIRIR225 signal, and both signals are easier to be bleached compared to a higher temperature pIRIR signal (pIRIR290), giving it an advantage for dating non-aeolian sediments. We conclude that the pulsed pIRIR225 protocol is not promising for FG polymineral samples as it has a tendency to significantly underestimate De values. However, it proves to be a feasible approach for dating CG K feldspar samples without fading correction, although the discrepancy between g-values and De values requires further investigation.