Comparison of feldspar dating protocols for loess samples older than 70 ka from the Tianshan Mountains, arid central Asia

Abstract

Previous studies have demonstrated that quartz optically stimulated luminescence (OSL) dating has limitations for samples older than the last glaciation. However, infrared stimulated luminescence (IRSL) from K-feldspar can be applied beyond this limit if the problem of anomalous fading can be overcome. Elevated temperature stimulated IRSL signals (pIRIR) have shown great potential for minimizing the underestimation. In this study, we compared three commonly applied protocols (pIR50IR290, pIR200IR290, MET-pIRIR) for the same set of loess samples from the Tianshan Mountains in arid central Asia (ACA). For loess samples in the 70–130 ka age range (i.e., De values in the range of 200–400 Gy), pIR200IR290 and MET-pIRIR could both be used for dating, while a varying degree of underestimation occurred for the pIR50IR290 dating protocol. For samples older than 130 ka (i.e., De values in the range of 400–700 Gy), the MET-pIRIR250 signal was the most suitable.