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

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journal contribution
posted on 2018-05-16, 14:01 authored by Andrew S Carr, Alex S. Hay, Mark Powell, Ian Livingstone
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.

Funding

ASH was supported by NERC studentship 1358108.

History

Citation

Quaternary Geochronology, 2019 49, pp. 85-91

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/School of Geography, Geology and the Environment/Physical Geography

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  • VoR (Version of Record)

Published in

Quaternary Geochronology

Publisher

Elsevier

issn

1871-1014

eissn

1878-0350

Acceptance date

2018-05-08

Copyright date

2018

Available date

2018-05-16

Publisher version

https://www.sciencedirect.com/science/article/pii/S1871101417301917

Language

en

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