Testing post-IR IRSL luminescence dating methods in the southwest Mojave Desert, California, USA

Carr, A. S., Hay, A. S., Powell, M. and Livingstone, I. (2018) Testing post-IR IRSL luminescence dating methods in the southwest Mojave Desert, California, USA. Quaternary Geochronology. 1871-1014. (In Press)

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Item Type:	Article
Abstract:	The Mojave Desert presents an array of Pleistocene lacustrine deposits and aeolian landforms to which, at times, it has proved challenging to apply luminescence methods. We tested the suitability of K-feldspar post-IR IRSL methods using two sites with independent radiocarbon dating – shorelines at Harper Lake and Silver Lake – considering: 1) overall performance of the post-IR IRSL 225°C (pIRIR225) protocol, 2) effect of test dose size on pIRIR225 De, 3) anomalous fading correction of pIRIR225 ages; 4) preliminary single grain pIRIR225 results. We observe consistently good performance of the single aliquot pIRIR225 protocol, with good dose recovery, acceptable recycling ratios, low recuperation and low inter-aliquot scatter. The pIRIR225 ages for Silver Lake (8.8 ± 0.4 and 11.3 ± 0.5 ka) and Harper Lake (both 25.4 ± 1.4 ka) are in substantially better agreement with the independent dating than low temperature (50°C) IRSL and quartz OSL ages. pIRIR225 fading rates are reduced to ~2.0-2.5% per decade, but there remains a tendency for under-estimation when using uncorrected ages. A need for fading correction is further implied at Harper Lake via comparison with multi-elevated temperature (MET)-PIR age plateaus and pIRIR290 measurements, although at the younger Silver lake site these methods produce ages nearly identical to the uncorrected pIRIR225 ages. Preliminary single grain pIRIR225 measurements suggest a ~25-30% usable grain yield. At Silver Lake the single grain and single aliquot ages agree well despite over-dispersion of the single grain equivalent dose distribution. At Harper Lake the single grain and single aliquot pIRIR225 ages also agree well, although a population of insensitive, lower De grains is observed. These grains are not associated with significantly higher fading rates.
Subjects:	G Geography. Anthropology. Recreation > GB Physical geography > GB400 Geomorphology. Landforms. Terrain > GB561 Other natural landforms: Floodplains, caves, deserts, dunes > GB611 Deserts
Creators:	Carr, Andrew S, Hay, Alex S, Powell, Mark and Livingstone, Ian
Publisher:	Elsevier
Faculties, Divisions and Institutes:	University Faculties, Divisions and Research Centres - OLD > Graduate School
Date:	10 May 2018
Date Type:	Published Online
Journal or Publication Title:	Quaternary Geochronology
Language:	English
DOI:	https://doi.org/10.1016/j.quageo.2018.05.006
ISSN:	1871-1014
Status:	In Press
Refereed:	Yes
URI:	http://nectar.northampton.ac.uk/id/eprint/10345

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