Single-grain TT-OSL bleaching characteristics: Insights from modern analogues and OSL dating comparisons
Arnold, LJ and Demuro, M and Spooner, NA and Prideaux, GJ and McDowell, MC and Camens, AB and Reed, EH and Pares, JM and Arsuaga, JL and Bermudez de Castro, JM and Carbonell, E, Single-grain TT-OSL bleaching characteristics: Insights from modern analogues and OSL dating comparisons, Quaternary Geochronology, 49 pp. 45-51. ISSN 1871-1014 (2019) [Refereed Article]
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.
luminescence dating, thermally transferred optically stimulated luminescence (TT-OSL), single-grain, modern analogues, Spain, Australia