Rock surface luminescence dating has developed into a promising approach to constrain depositional ages of clasts. The prerequisites for its successful application are the precise determination of the clast-specific dosimetry and the sufficient pre-burial resetting of the luminescence signal into a certain depth beneath the clast-surface. Dosimetry of clasts is significantly influenced by the internal beta dose rate, which largely depends on grain-size range and internal potassium content of feldspar within rock slices. In the current study, six clasts are investigated from three distinct fluvial terraces of the Bruche River in north-eastern France. Previously published independent age control from sandy deposits of the terraces indicate depositional ages of similar to 12-14 ka for the youngest, similar to 27-35 ka forthe middle, and a minimum age of similar to 200 ka forthe oldest terrace. Clast-based multi-elevated-temperature post-IR infrared stimulated luminescence (pIR) ages show systematic deviations from age control, overestimating by similar to 50-150% for the youngest terrace, similar to 10-30% for the middle terrace, but confirming the minimum age for the oldest terrace. The present study provides methodological advancements by estimating grain-size range and Kcontent in feldspar grains within rock slices using mu-X-rayfluorescence and microprobe analysis, respectively. Modern clasts from the present riverbed indicate that high-temperature pIR signals retain significant residual ages in rock slices, ranging from similar to 2-3 ka for pIR110 over similar to 5-6 ka for pIR170 to similar to 8 ka for pIR225 signals, while IR50 residual ages remain negligible (<1 ka). This study also demonstrates the potential for using fully saturated rock slices from clast interiors to perform reliable fading correction. As the clast-based luminescence ages overestimate the corresponding ages derived from sandy deposits, this highlights the remaining limitations that must be considered for this approach.
Over the past decade, the use of portable optically stimulated luminescence (OSL) readers has expanded rapidly, enabling the recovery of latent stratigraphic information from bulk sediments of late Quaternary age. These applications assume that luminescence signals from sample aliquots are reproducible, yet no study has explicitly examined preparation strategies that optimize inter-aliquot consistency. Consequently, no standardized methods for sample preparation exist in portable OSL research. This study initiates this discussion by testing how aliquot preparation and sample size influence reproducibility. Four samples were collected from postglacial eolian dunes in Alberta, Canada. For each sample, 20 aliquots were prepared using four approaches, yielding 320 aliquots: (a) monogranular layers of equal volume portions (similar to 1.5 g), (b) monogranular layers of equal-weight (1.5 g), (c) monogranular layers mounted on double-sided adhesive segments of equal area (similar to 1.0 g), and (d) multilayer portions of equal weight (12.0 g). All aliquots were analyzed with a portable OSL reader. Statistical results showed that for blue-OSL signals, reproducibility varied both among samples and across preparation methods. However, multilayer aliquots prepared with equal weights (12 g) consistently produced the highest reproducibility, suggesting that larger grain populations enhance inter-aliquot consistency. For IRSL signals, no preparation method offered a clear advantage.
The rapid increase in tree-ring radiocarbon concentration of 12‰ between 774–775 CE marked the first confirmed cosmic-origin event identified through annual tree-ring records. Subsequent studies have in-dependently verified this signal in dendrochronologically dated material from multiple regions, confirm-ing its global nature. Since then, several comparable events have been identified across different peri-ods. These radiocarbon spikes are of particular importance because they provide precise annual tie-points that can significantly improve chronological resolution in fields such as archaeology and geology. In this paper, we present a simple method for detecting such events in high-resolution radiocarbon da-tasets.
The rapid increase in tree-ring radiocarbon concentration of 12 parts per thousand between 774-775 CE marked the first confirmed cosmic-origin event identified through annual tree-ring records. Subsequent studies have independently verified this signal in dendrochronologically dated material from multiple regions, confirming its global nature. Since then, several comparable events have been identified across different periods. These radiocarbon spikes are of particular importance because they provide precise annual tie-points that can significantly improve chronological resolution in fields such as archaeology and geology. In this paper, we present a simple method for detecting such events in high-resolution radiocarbon datasets.
Optical Stimulated Luminescence (OSL) screening has emerged as a significant advancement in the field of luminescence dating applications. The employed portable luminescence readers offer practical and efficient tools for on-site measurements. In contrast to traditional luminescence dating in the laboratory, which often involves analyzing enriched quartz or feldspar mineral separates, portable OSL readers typically measure infrared (IR) or blue post-IR OSL signals from unprocessed bulk material. Here, we present a new device series that can be used as a portable OSL reader for dating purposes and luminescence screening: the OSL Helios reader. The reader has already been used in luminescence laboratories as a bench-top device for dosimetry research for almost twenty years. It recently received significant upgrades for better versatility. Our contribution demonstrates the application of the OSL Helios reader for luminescence screening on a loess profile, where luminescence signal intensities were assessed for specific sedimentological layers. The profile was measured using different versions of the OSL Helios reader, and the results were compared to those of the SUERC reader, which is commonly used as a portable reader in applications. Additionally, standard passive dosimeters (Al2O3:C and BeO), as well as detectors considered for emergency dosimetry (NaCl), were measured to determine the sensitivity of Helios devices. We conclude that the Helios reader performs similarly to the SUERC reader in most standard situations and can be considered an additional option for portable luminescence reader application.
