Elevated temperature IRSL dating of loess sections in the East Eifel region of Germany

Abstract

It has been shown that the infrared stimulated luminescence signals measured at elevated temperature after an IR stimulation at 50 °C (post-IR IRSL) are significantly more stable than the conventional IRSL at 50 °C (IR50). In this study a post-IR IRSL protocol using a second IR stimulation temperature of 290 °C (pIRIR290) was applied to 17 polymineral fine grain (4–11 μm) samples from various loess sections in the Eifel region (Wannenköpfe, Dachsbusch, Kärlich and Ariendorf) with independent age control to test the reliability of ages using the pIRIR290 signal. The laboratory-measured fading rates are below 1%/decade on average for the pIRIR290. Both IR50 and pIRIR290 signals of 9 samples were found to be in field saturation. The average ratio of the sensitivity-corrected natural signal to the laboratory saturation level for the pIRIR290 is 0.98 ± 0.02 (n = 9), showing that field saturation is equal to laboratory saturation for the pIRIR290 signal from polymineral fine grains from the Eifel region. Minimum equivalent dose estimates were calculated from the characteristic saturation dose of the dose response curves, giving minimum ages estimates of ∼230–420 ka, and suggesting that the pIRIR290 signal can be used to date loess to ∼300 ka. The pIRIR290 ages estimates of the samples from the Wannenköpfe and Dachsbusch sites are in good agreement with independent age control showing that the IRSL dating using pIRIR290 signal without fading correction is apparently reliable. Our data suggest that the loess units E, F, G and the lower part of H at the Kärlich site were accumulated >270 ka and that the palaeosol of the Kärlich Interglacial I most likely developed during marine isotope stage (MIS 9) or earlier. The pedocomplex on the top of Loess bed II at the Ariendorf section can be correlated with MIS 7.