Single-grain K-feldspar post-IR IRSL dating of glaciofluvial sediments of Guxiang Glaciation in SE Tibetan Plateau

The Guxiang Glaciation, a key reference for classifying late Quaternary glaciations on the Tibetan Plateau, has been dated to MIS 6 using cosmogenic 10Be exposure dating of two boulders. However, additional dating methods are needed to evaluate and improve its chronology. In this study, we used the post-infrared infrared stimulated luminescence (post-IR IRSL) signal at 225 °C from single K-feldspar grains to date a lateral moraine corresponding to the Guxiang Glaciation in the Bodui Zangbo Valley, southeastern Tibetan Plateau. Six samples from glaciofluvial sand lenses interbedded within the moraine were analyzed. The LnTn method was utilized for De determination to avoid truncation in De distribution and age underestimation. A common standardized growth curve (SGC) was established for all samples, and the least-squares (LS)-normalized Ln/Tn values of the brightest grains were selected for Ln/Tn and De estimation using the central age model (CAM). Using one fading-correction model, the post-IR IRSL ages (159 ± 9 ka to 181 ± 11 ka, average value of 173 ± 4 ka) fall within the expected MIS 6 interval and align with previous 10Be exposure ages. However, the ages are close to the limit of the method, and a different model for correcting fading suggests a much older age (average 308 ± 27 ka). This study reveals both the potential and challenges of single-grain K-feldspar luminescence dating as a means to establish chronological control for glaciations beyond the last glacial period on the Tibetan Plateau.