Sediment mixing in aeolian sandsheets identified and quantified using single-grain optically stimulated luminescence

Gliganic, Luke A., Cohen, Tim J., Slack, Michael, and Feathers, James K. (2016) Sediment mixing in aeolian sandsheets identified and quantified using single-grain optically stimulated luminescence. Quaternary Geochronology, 32. pp. 53-66.

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Abstract

Post-depositional mixing processes are extremely common and often obscure a record of deposition in dune and sand sheet deposits. We show that the upper half metre of a dune in southeastern Australia is currently being turned over through bioturbation, but that single-grain OSL dating and contextual knowledge can be used to identify and model these modern mixing processes. In the sandy deposits investigated, mixing processes were observed to be acting to a predicable depth of ∼50–60 cm. This observation was used to develop a conceptual framework that can be applied to buried deposits and used to temporally constrain the evolution of the landform and quantify rates of mixing. When our mixing zone conceptual framework was combined with the MAM we show that phases of significant dune aggradation occurred at ∼29.9, ∼18.3, ∼10.3 ka, and continued through the Holocene. We also present an approach using single-grain OSL data to estimate downward mixing rates, which show a strong depth dependency and are coherent with previously reported mixing rates. Modern downward mixing rates indicate that the upper ∼50 cm (Zone 1) will be completely turned over on millennial time scales. While caution needs to be used when interpreting archaeological and OSL data from bioturbated sandy environments, our results demonstrate that contextual knowledge and single-grain OSL data can resolve mixing processes and contribute to an understanding of landscape evolution.

Item ID: 47416
Item Type: Article (Research - C1)
ISSN: 1878-0350
Keywords: aeolian dunes; OSL dating; bioturbation; sandsheet; mixing rate
Funders: Scarp Archaeology, Rio Tinto Coal and Allied
Date Deposited: 21 Feb 2017 06:01
FoR Codes: 21 HISTORY AND ARCHAEOLOGY > 2101 Archaeology > 210102 Archaeological Science @ 70%
21 HISTORY AND ARCHAEOLOGY > 2101 Archaeology > 210101 Aboriginal and Torres Strait Islander Archaeology @ 30%
SEO Codes: 95 CULTURAL UNDERSTANDING > 9505 Understanding Past Societies > 950503 Understanding Australias Past @ 100%
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