2026/05/27 by Arindam Biswas, Svenja Riedesel, Louise Karman-Besson +4 · 1 voice
Earth and Planetary Sciences · Engineering · #Geological formations and processes #Hydrocarbon exploration and reservoir analysis #Seismic Imaging and Inversion Techniques
paper · doi:10.5194/gchron-8-297-2026
openalex created_date 2025/10/17 · openalex publication_date 2026/05/27 · openalex updated_date 2026/07/30
Abstract. Post-infrared infrared stimulated luminescence (post-IR IRSL) signals from potassium feldspars are gaining prominence in both luminescence dating and luminescence-based sediment tracing techniques. To enhance the accuracy and reliability of these applications, it is essential to develop a comprehensive understanding of how post-IR IRSL signals undergo bleaching. While previous studies have explored post-IR IRSL bleachability using multi-grain approaches, a systematic single-grain investigation on modern analogues has not been conducted. In this study, we examined the bleaching behaviour of the post-infrared infrared stimulated luminescence signal measured at 200 °C (post-IR IRSL200) at the single-grain level in eleven modern floodplain samples from the tectonically active Southern Central Andes. Our study demonstrated considerable variation in the residual doses following 2 d of laboratory solar simulator bleaching across the sample set. This variability was evident not only between different samples but also among individual grains within the same sample. Thus, we evaluated the influence of bleaching duration, grain-specific geochemical composition, catchment-scale lithological variability, and the size of the natural dose on the laboratory-measured residual doses. Our laboratory bleaching experiments in which single grains were given a fixed regenerated dose of 30 Gy prior to solar simulator exposure showed similar post-IR IRSL200 signal bleaching behaviour across four different samples, reaching a plateau based on normalised luminescence signal after 2 d of exposure to solar simulator light. While individual grains exhibited a wide range of bleaching rates, this variability did not account for the spread in residual dose values. Notably, extended light exposure reduced variability in signal intensity, underscoring its role in dose homogenisation. Geochemical analysis of major oxides showed no significant correlation with either residual dose magnitude or bleaching rate, suggesting that mineral composition (including K-concentration) does not influence bleaching efficiency at the individual grain level. Furthermore, bleaching behaviour remained consistent across samples regardless of catchment lithology, with no discernible relationship between lithological units and remnant dose (defined as the natural dose remaining at the time of deposition and burial) or residual dose values. Most importantly, we identified a strong positive linear correlation (R2= 0.89) between residual dose and natural remnant dose, revealing dose-dependent bleaching efficiency and the presence of a negligible unbleachable component at the time of deposition. This relationship between residual dose and natural remnant dose also suggests that while the youngest samples (with low natural remnant dose) could reach zero residual dose, the relatively older samples (with more than 10 Gy of natural remnant dose) could show a significant amount of residual dose. By integrating insights on bleachability with the information on the unbleachable component and remnant doses derived from modern analogues, we highlight the limitations of correcting palaeodoses by directly using either residual or remnant doses and evaluate three context-sensitive correction strategies. Finally, we discuss how residual doses can be leveraged to more reliably identify well-bleached grains, enhancing the accuracy of luminescence-based sediment tracing applications.