IRSL and post-IR IRSL residual doses recorded in modern dust samples from the Chinese Loess Plateau

Abstract

Using a set of modern/young (0 to about 200 years old) dust samples collected from the Chinese Loess Plateau the bleachability of IRSL measured at 50°C (IR 50 ) and post-IR 50 elevated temperature IRSL (measured at 225°C and at 290°C) is investigated by measuring the apparent (residual) doses recorded by these signals. Doses recorded by quartz OSL are used as a reference. Allowing for differences in dose rates it seems that both IRSL and post-IR IRSL signals yield residual doses that are significantly larger than the doses measured in quartz. These residual doses can be largely explained by thermal transfer caused by preheating. Nevertheless, we advise against the use of a low temperature preheat (<200°C) with IR 50 to date loess samples because, as has been reported before, the signal appears to be thermally unstable. In general, we conclude that it may not be advisable to apply post-IR IRSL dating to Chinese loess samples where residuals of up to ~20 Gy are a significant fraction of the total dose. However, these residuals quickly become unimportant when dating older samples, and this is the age range in which post-IR IRSL dating is likely to be most useful.

On the dose dependency of the bleachable and non-bleachable components of IRSL from K-feldspar: Improved procedures for luminescence dating of Quaternary sediments

“…This highlights the importance of obtaining accurate and precise constraints on the residual doses of all samples and not only those deposited recently, especially when stimulated at elevated temperatures. From these results and from those of other studies (e.g., Li and Li, 2011a;Buylaert et al, 2011;Stevens et al, 2011;Nian et al, 2012), it is clear that the residual dose associated with the non-bleachable component is highly variable from sample to sample, and that sunlight bleaching tests should be routinely conducted to estimate the likely minimum size of the residual dose at the time of sample deposition.…”

“…In practice, researchers have estimated the residual doses from modern analogues or from artificially bleached samples, and these doses have been subtracted from the equivalent dose (D e ) measured using one of the pIRIR procedures (e.g., Buylaert et al, 2011;Li and Li, 2011a). There have been no systematic investigations yet, however, of the properties of the residual signal, nor of its effect on the accuracy of pIRIR age estimates.…”

“…For example, Buylaert et al (2011) reported residual doses of up to ~20 Gy for the pIRIR 290°C signal [pIRIR(290)] from samples of modern Chinese loess, and Stevens et al (2011) observed residual doses as high as ~40 Gy for loess samples from the southern Carpathian Basin. Lowick et al (2012) reported highly variable residual doses in the pIRIR (290) signals, ranging up to ~150 Gy, and found that significantly large residual doses may be present when sunlight is attenuated by water.…”

Modelling dose rate to single grains of quartz in well-sorted sand samples: The dispersion arising from the presence of potassium feldspars and implications for single grain OSL dating

“…This age overestimation of ~2 ka is not surprising given the 293 young age of the sample since it is well-known that residual, difficult-to-bleach doses affect post-IR IRSL 294 D e determination from young samples. It corresponds to a residual dose of ~6 Gy for this signal, which 295 fits within the variability of observed residual doses for well-bleached samples (i.e., samples sufficiently 296 exposed to sunlight to reset the quartz OSL signal; see, e.g., Buylaert et al, 2011). This further indicates 297 that the quartz OSL from this sample is most likely unaffected by poor-bleaching.…”

Post-IR IRSL dating of K-feldspar from last interglacial marine terrace deposits on the Kamikita coastal plain, northeastern Japan

“…It has been suggested that the fading of the pIRIR 290 signal is negligible in nature, because in very old samples measured by some studies the natural signal was close to the saturation level (Buylaert et al, 2011;Kars et al, 2012;Thiel et al, 2011b;Thomsen et al, 2011). Stability of the pIRIR 290 signal has also been inferred from age comparisons with an independent age control (Thiel et al, 2011a;Zander and Hilgers, 2013).…”