Testing the potential of using coarse-grain feldspars for post-IR IRSL dating of calcium sulphate-wedge growth in the Atacama Desert

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1016/j.quageo.2022.101341. This is version 1 of this Preprint.

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Authors

Aline Zinelabedin, Svenja Riedesel , Tony Reimann, Benedikt Ritter, Tibor Dunai

Abstract

The growth of vertically laminated calcium-sulphate wedges in the Atacama Desert is assumed to be driven by the interaction of moisture supply and salt dynamics in the subsurface. Geochronological data of these wedge laminations is yet sparse but indispensable to resolve wedge-growth phases and episodes of moisture supply and to use these deposits as a palaeoclimate archive in the hyperarid environment. Our pilot study presents a first approach of dating a calcium-sulphate wedge from the Atacama Desert using coarse-grain feldspar luminescence dating. Our results show a widespread and clustered equivalent-dose distribution of two wedge samples from ~20 Gy up to saturation. Optically stimulated luminescence (OSL) of quartz revealed unsuitable properties for dating wedge deposits. Consequently, we applied post-infrared infrared stimulated luminescence (post-IR IRSL) to coarse-grained feldspars. Since feldspar single-grain measurements yielded a low number of luminescent grains, we used 1 mm aliquots as reliable single-grain proxies for genuine single-grain measurements. Data from energy-dispersive x-ray spectroscopy (EDX) showed that the feldspar single grains have large differences in their internal K content, resulting in an averaged internal K content of 3.9 ± 1.0 % for all luminescent grains. This result was subsequently used for dose rate and age calculations. Our results of equivalent-dose distributions and palaeodoses derived from the minimum age model reveal most recent wedge-growth activities at 10.6 ± 2.2 ka and 7.9 ± 1.8 ka for the two wedge samples.

DOI

https://doi.org/10.31223/X52069

Subjects

Earth Sciences

Keywords

Calcium-sulphate wedge, Atacama Desert, Feldspar, Post-IR IRSL, Wedge-growth dating

Dates

Published: 2022-08-04 10:29

License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
The authors will make the data available upon request to the correspondign author.

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