Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
11030942 | Radiation Measurements | 2018 | 10 Pages |
Abstract
Thermally-Transferred Optically Stimulated Luminescence (TT-OSL) from quartz is an extended-range luminescence dating technique, with an assumed potential to date sediments as old as early Pleistocene (0.8-2.6â¯Ma). However, one of the main drawbacks of the TT-OSL signal is its relatively low thermal stability. The few and scattered estimates in the literature of the relatively low thermal stability highlight the possibility that some reported TT-OSL ages are thermal artefacts (i.e. minimum ages only). In this study, we rigorously investigate the thermal stability of the main TT-OSL source trap, using a combination of laboratory and analytical techniques (varying heating rates, isothermal decay, alongside several models) on multiple aliquots of a modern sand sample from the eastern Mediterranean coastal plain. The varying heating rates method constrains the Arrhenius parameters of the TT-OSL main trap to Eâ¯=â¯1.50â¯Â±â¯0.06â¯eV and sâ¯=â¯1012.8±0.6 sâ1; these values translate into a trap lifetime of 3.2â1.9+4.8 Ma at 10â¯Â°C. Isothermal decay data further exhibits significant departures from first-order kinetic behavior, which can be well captured by either the general order kinetics model, or a Gaussian distribution of first-order systems. However, extrapolations of these models to geological timescales are at odds with a large volume of observations, thus suggesting that the deviation from first-order kinetics may be a laboratory artefact. Overall, our study reinforces the concern, that thermal loss progressively affects the TT-OSL signal in the Ma-scale age range, and that some previously reported results may be “minimum ages” only.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Radiation
Authors
Galina Faershtein, Benny Guralnik, Renske Lambert, Ari Matmon, Naomi Porat,