A progressively elevated temperature (PET) IRSL SAR procedure – first experiments and results

Abstract. Infrared stimulated luminescence (IRSL) dating is a common technique for dating feldspar-bearing sediment deposits. The technique is preferentially applied as a single aliquot regenerative (SAR) protocol derivative: Post-infrared infrared (pIR_1stIR_2nd) and multiple elevated temperature (MET) SAR protocols. Both of these techniques aim to reduce problems with unstable luminescence traps common to feldspars, known as anomalous fading. Elimination of the unstable IRSL signal component, which may lead to age underestimation, is achieved by sequential sampling of the IRSL signal at either two (pIR_1stIR_2nd) or a few (MET) discrete temperatures, usually in the range 50 °C to 290 °C. We propose a modified approach, the progressively elevated temperature (PET) IRSL SAR, which continuously records the luminescence signal while progressively elevating the sample temperature. The benefits of this approach include the generation of quasi-continuous data chains, beginning with the recorded PET-IRSL signal curves, over De-value curves relevant for palaeodose assessment, a-value curves used for dose-rate refinement, and g-value curves serving to assess the signal loss resulting from fading. In addition to anomalous fading problems, feldspars do not bleach as quickly and thoroughly as quartz, potentially resulting in age overestimation. The illustrative PET data curves may be useful in illustrating a sample´s bleaching and fading history. Thus, they may allow users to both reduce problems with anomalous fading and identify aliquots that are least impacted by incomplete bleaching.