☆ 4.2 Article

Comparing the accuracy and precision of luminescence ages for partially-bleached sediments using single grains of K-feldspar and quartz

QUATERNARY GEOCHRONOLOGY (2019)

期刊

QUATERNARY GEOCHRONOLOGY

卷 53, 期 -, 页码 -

出版社

ELSEVIER SCI LTD

DOI: 10.1016/j.quageo.2019.101007

关键词

Single grains; Post-IR IRSL; K-feldspar; OSL; Quartz; Partially-bleached

类别

Geography, Physical Geosciences, Multidisciplinary

资金

Natural Environment Research Council consortium grant [NE/J008672/1]
European Research Council under the European Union Horizon 2020 research and innovation programme [ERC-2014-StG 639904 -RELOS]
Aarhus University [AUFF-F2018-6-1 1]
NERC [NE/J008672/1] Funding Source: UKRI

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摘要

Glacial settings are considered to be the most challenging context for the application of luminescence dating. The optically stimulated luminescence (OSL) signal of quartz is often preferred for luminescence dating in partially bleached settings as it resets (or bleaches) more rapidly in response to sunlight than the post-IR IRSL (pIRIR) signal of K-feldspar, and can therefore better characterise the well-bleached part of the partially-bleached De distribution. However, the relative bleaching extents of single grains of quartz and K-feldspar have not yet been compared for sedimentary samples from the natural environment. Here we compare the D, distributions and accuracy and precision of ages determined using single grains of quartz and K-feldspar from sedimentary samples deposited in a proglacial setting with independent age control. We found that the extent of bleaching of the OSL signal of quartz and pIRIR(225) signal of K-feldspar was similar (with similar over-dispersion), and therefore the pIRIR(225) signal bleached to similarly low levels as the OSL signal of quartz in this partially-bleached setting. We also observed a consistent offset in over-dispersion between quartz and K-feldspar of 10% that can be linked to scatter arising from internal dose-rates of K-feldspar and should be included when applying age models. The results here demonstrate that the accuracy and precision of ages determined using the pIRIR(225) signal of single grains of K-feldspar were similar to the OSL signal of quartz. However, K-feldspars were 5-18 times more efficient than quartz at determining the population of interest for age calculation as a larger proportion of K feldspar grains emitted a detectable luminescence signal in comparison to quartz. These findings contradict our current understanding of the bleaching of K-feldspar and quartz grains in the natural environment, and are likely applicable to other partially-bleached settings (e.g. fluvial, alluvial).

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Dating of the late Quaternary high lake levels in the Jilantai area, northwestern China, using optical luminescence of quartz and K-feldspar

Yuxin Fan, Zhenjun Li, Qingsong Cai, Guangliang Yang, Qingsong Zhang, Hui Zhao, Fahu Chen, Mehran Maghsoudi

Summary: Recent studies have shown high lake levels in western China during the late Quaternary, with intervals of higher lake levels during Marine Isotope Stage (MIS) 5e and MIS 3a-Last Glacial Maximum (LGM) in the Jilantai sub-depression. These high lake levels were likely a geomorphic response to dry climatic conditions rather than representative of humid climates in arid regions.

JOURNAL OF ASIAN EARTH SCIENCES (2022)