Smedley, RK and Duller, GAT and Roberts, HM (2015) Bleaching of the post-IR IRSL signal from individual grains of K-feldspar: Implications for single-grain dating. Radiation Measurements, 79. 33 -42. ISSN 1350-4487

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Abstract

Post-IR IRSL (pIRIR) signals from K-feldspar grains measured at elevated temperatures are increasingly being used for dating sediments. Unfortunately the pIRIR signal from K-feldspars bleaches more slowly than other signals (e.g. OSL from quartz) upon exposure to daylight, leading to concerns about residual signals remaining at deposition. However, earlier studies have not assessed whether the pIRIR signal bleaches at the same rate in all feldspar grains. In this study laboratory bleaching experiments have been conducted and for the first time the results show that the rate at which the pIRIR signal from individual K-feldspar grains bleach varies. To determine whether grain-to-grain variability in bleaching rate has a dominant control on equivalent dose (De) distributions determined using single grains, analysis was undertaken on three samples with independent age control from different depositional environments (two aeolian and one glaciofluvial). The De value determined from each grain was compared with the rate at which the pIRIR225 signal from the grain bleaches. The bleaching rate of each grain was assessed by giving a 52 Gy dose and measuring the residual De after bleaching for an hour in a solar simulator. There is no clear relationship between the rate at which the pIRIR225 signal of an individual grain bleaches and the magnitude of its De. It is concluded that variability in the bleaching rate of the pIRIR225 signal from one grain to another does not appear to be a dominant control on single grain De distributions.

Item Type: Article
Uncontrolled Keywords: Feldspar; Luminescence; Single grains; Infrared stimulated luminescence; pIRIR; Residual De values; Bleaching rate
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
Divisions: Faculty of Natural Sciences > School of Geography, Geology and the Environment
Depositing User: Symplectic
Date Deposited: 16 Feb 2017 15:44
Last Modified: 12 Jul 2017 08:23
URI: http://eprints.keele.ac.uk/id/eprint/2909

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