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Sampling Methods for Luminescence Dating of Subsurface Deposits from Cores
Open AccessArticle

Testing Luminescence Dating Methods for Small Samples from Very Young Fluvial Deposits

1
Department of Geology, Kansas State University, Manhattan, KS 66506, USA
2
Illinois State Geological Survey, Prairie Research Institute, Champaign, IL 61820, USA
3
Department of Geography and Geospatial Sciences, Kansas State University, Manhattan, KS 66506, USA
*
Author to whom correspondence should be addressed.
Methods Protoc. 2019, 2(4), 90; https://doi.org/10.3390/mps2040090
Received: 2 October 2019 / Revised: 2 December 2019 / Accepted: 4 December 2019 / Published: 6 December 2019
(This article belongs to the Special Issue Methods in Dating and Other Applications using Luminescence)
The impetus behind this study is to understand the sedimentological dynamics of very young fluvial systems in the Amazon River catchment and relate these to land use change and modern analogue studies of tidal rhythmites in the geologic record. Initial quartz optically stimulated luminescence (OSL) dating feasibility studies have concentrated on spit and bar deposits in the Rio Tapajós. Many of these features have an appearance of freshly deposited pristine sand, and these observations and information from anecdotal evidence and LandSat imagery suggest an apparent decadal stability. The characteristics of OSL from small (~5 cm) sub-samples from ~65 cm by ~2 cm diameter vertical cores are quite remarkable. Signals from medium-sized aliquots (5 mm diameter) exhibit very high specific luminescence sensitivity, have excellent dose recovery and recycling, essentially independent of preheat, and show minimal heat transfer even at the highest preheats. These characteristics enable measurement of very small signals with reasonable precision and, using modified single-aliquot regenerative-dose (SAR) approaches, equivalent doses as low as ~4 mGy can be obtained. Significant recuperation is observed for samples from two of the study sites and, in these instances, either the acceptance threshold was increased or growth curves were forced through the origin; recuperation is considered most likely to be a measurement artefact given the very small size of natural signals. Dose rates calculated from combined inductively coupled plasma mass spectrometry/inductively coupled plasma optical emission spectrometry (ICP-MS/ICP-OES) and high-resolution gamma spectrometry range from ~0.3 to 0.5 mGya−1, and OSL ages for features so far investigated range from 13 to 34 years to several 100 years. Sampled sands are rich in quartz and yields of 212–250 μm or 250–310 μm grains indicate high-resolution sampling at 1–2 cm intervals is possible. Despite the use of medium-sized aliquots to ensure the recovery of very dim natural OSL signals, these results demonstrate the potential of OSL for studying very young active fluvial processes in these settings. View Full-Text
Keywords: Amazon; Rio Tapajós; quartz OSL dating; small samples; very high specific sensitivity; very young fluvial deposits Amazon; Rio Tapajós; quartz OSL dating; small samples; very high specific sensitivity; very young fluvial deposits
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MDPI and ACS Style

Spencer, J.Q.G.; Huot, S.; Archer, A.W.; Caldas, M.M. Testing Luminescence Dating Methods for Small Samples from Very Young Fluvial Deposits. Methods Protoc. 2019, 2, 90. https://doi.org/10.3390/mps2040090

AMA Style

Spencer JQG, Huot S, Archer AW, Caldas MM. Testing Luminescence Dating Methods for Small Samples from Very Young Fluvial Deposits. Methods and Protocols. 2019; 2(4):90. https://doi.org/10.3390/mps2040090

Chicago/Turabian Style

Spencer, Joel Q.G.; Huot, Sébastien; Archer, Allen W.; Caldas, Marcellus M. 2019. "Testing Luminescence Dating Methods for Small Samples from Very Young Fluvial Deposits" Methods Protoc. 2, no. 4: 90. https://doi.org/10.3390/mps2040090

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