Single-grain TT-OSL bleaching characteristics: Insights from modern analogues and OSL dating comparisons

• Published in: Quaternary geochronology 2019-02, Vol.49, p.45-51
• Main Authors: Arnold, Lee J., Demuro, Martina, Spooner, Nigel A., Prideaux, Gavin J., McDowell, Matthew C., Camens, Aaron B., Reed, Elizabeth H., Parés, Josep María, Arsuaga, Juan Luis, Bermúdez de Castro, José María, Carbonell, Eudald
• Format: Article
• Language: English
• Subjects: Australia; Luminescence dating; Modern analogues; Single-grain; Spain; Thermally transferred optically stimulated luminescence (TT-OSL)
• ISSN: 1871-1014; 1878-0350
• DOI: 10.1016/j.quageo.2018.01.004

Previous assessments of thermally transferred optically stimulated luminescence (TT-OSL) signal resetting in natural sedimentary settings have been based on relatively limited numbers of observations, and have been conducted primarily at the multi-grain scale of equivalent dose (De) analysis. In this study, we undertake a series of single-grain TT-OSL bleaching assessments on nineteen modern and geological dating samples from different sedimentary environments. Daylight bleaching experiments performed over several weeks confirm that single-grain TT-OSL signals are optically reset at relatively slow, and potentially variable, rates. Single-grain TT-OSL residual doses range between 0 and 24 Gy for thirteen modern samples, with >50% of these samples yielding weighted mean De values of 0 Gy at 2σ. Single-grain OSL and TT-OSL dating comparisons performed on well-bleached and heterogeneously bleached late Pleistocene samples from Kangaroo Island, South Australia, yield consistent replicate age estimates. Our results reveal that (i) single-grain TT-OSL residuals can potentially be reduced down to insignificant levels when compared with the natural dose range of interest for most TT-OSL dating applications; (ii) the slow bleaching properties of TT-OSL signals may not necessarily limit their dating applicability to certain depositional environments; and (iii) non-trivial differences may be observed between single-grain and multi-grain TT-OSL bleaching residuals in some modern samples. Collectively, these findings suggest that single-grain TT-OSL dating may offer advantages over multi-grain TT-OSL dating in certain complex depositional environments. •TT-OSL bleaching assessments performed on 19 samples from different settings.•Modern sample TT-OSL residual doses range between 0 and 24 Gy.•Residuals are variable both within and between different depositional environments.•Differences were observed between single-grain and multi-grain TT-OSL residual doses.•Consistent OSL and TT-OSL ages obtained for late Pleistocene cave and beach deposits.