A new approach towards anomalous fading correction for feldspar IRSL dating — tests on samples in field saturation

Abstract

Anomalous fading of the feldspar infrared stimulated luminescence (IRSL) signal hampers possibilities of using feldspar IRSL to obtain burial ages for sediments beyond the dating range of quartz optically stimulated luminescence. Here, we propose a new approach to quantify anomalous fading of the feldspar IRSL signal over geological burial times based on laboratory fading experiments. The approach builds on the description of the quantum mechanical tunnelling process recently proposed by Huntley [2006. An explanation of the power-law decay of luminescence. J. Phys. Condensed Matter 18, 1359–1365]. We show that our methods allow the construction of un-faded and natural IRSL dose–response curves as well as anomalous fading rates in field saturation. The predicted level of field saturation closely approximates the measured saturation level for five samples from fluvial deposits (Lower Rhine) known to be older than 1 Ma. The modelled anomalous fading rate in field saturation (13.4% per decade) is close to the measured value of 11.2% per decade. These results indicate that the proposed method may allow anomalous fading corrected IRSL dating beyond the linear part of the IRSL dose–response curve.