1637 / 2019-08-23 21:29:39

长石红外信号的异常衰退及校正模型

1、第四纪地质与全球变化 > 专题6：第四纪年代学进展及应用

K-feldspar infrared stimulated luminescence (IRSL) signal has a more extended dating range than that of quartz optically stimulated luminescence (OSL) signal. However, the athermal signal loss, known as anomalous fading, holds back the application of K-feldspar IRSL dating for relatively old sediments. Although the post-IR IRSL (pIRIR) signals without fading were proposed [1,2], such athermally stable signals tend to be more difficult to bleach. For dating sediments from difficult-to-bleach environments, one has to choose a signal which still fades and the age has to be corrected for fading. Specifically, for old samples close to or in field saturation, a fading correction model was proposed by Kars et al. (2008) [3] to construct the simulated natural dose response curve and determine the saturation level on the basis of quantum mechanical tunnelling model [4]. However, ~10% underestimation of field saturation level was observed [3], suggesting a potential age over-correction. The loess-palaeosol sequences on the Chinese Loess Plateau contain homogenous and quasiconsistent wind-blown dusts with independent age control for the entire Quaternary. Therefore, these loess-palaeosol sequences provide an ideal material to test the reliability of the fading correction model mentioned above, and determine the upper dating limit of multiple IRSL signals from K-feldspar. In this study, loess samples collected from Luochuan loess profile are used for the K-feldspar pIRIR and pulsed IRSL measurements. The natural dose response curve (DRC) is constructed using the natural luminescence intensities from all samples and the corresponding independent ages. After the construction of the simulated natural DRCs following the fading correction model [3], the natural and simulated natural DRCs are compared to evaluate the reliability of the fading correction near field saturation, and to determine the upper dating limit for the pIRIR and pulsed IRSL signals using the D0s from both DRCs. We also compared the fading corrected ages following Huntley and Lamothe (2001) and Lamothe et al. (2003) with independent age and evaluate where the methods start to be inapplicable.


References

1. Thiel, C., Buylaert, J-P., Murray, A. S., Terhorst, B., Hofer, I., Tsukamoto, S., Frechen, M., 2011. Luminescence dating of the Stratzing loess profile (Austria)—Testing the potential of an elevated temperature post-IR IRSL protocol. Quaternary International. 234, 23-31. 2. Li, B., Li, S-H., 2011. Luminescence dating of K-feldspar from sediments: A protocol without anomalous fading correction. Quaternary Geochronology 6, 468-479. 3. Kars, R.H., Wallinga, J., Cohen, K.M., 2008. A new approach towards anomalous fading correction for feldspar IRSL dating—tests on samples in field saturation. Radiation Measurement 43, 786-790. 4. Huntley, D.J., 2006. An explanation of the power-law decay of luminescence. J. Phys. Condensed Matter 18, 1359-1365.