Single-grain OSL dating of fluvial terraces in the upper Hunter catchment, southeastern Australia

Xiao Fu*, Tim J. Cohen, Kirstie Fryirs

*Corresponding author for this work

    Research output: Contribution to journalArticle

    4 Citations (Scopus)

    Abstract

    Fluvial terraces in the upper Hunter catchment, southeastern Australia provide a long-term record of river activity in response to climate change in the late Quaternary. Single-grain optically stimulated luminescence (OSL) dating of quartz was applied in this study to investigate the timing of the formation of three fluvial terraces in the upper Hunter catchment. A detailed examination of luminescence properties of individual quartz grains revealed some correlation between their OSL decay rates, intrinsic brightness and dose saturation characteristics. Some quartz grains containing a higher proportion of non-fast components exhibit low brightness in OSL signals and high dose saturation levels. Some grains with slow OSL decays pass the standard rejection criteria, but are likely to yield underestimated equivalent doses (Des) because of a higher contribution of non-fast components, which are shown to have low thermal stability. Different rejection criteria, including the fast ratio, the dose saturation level and the OSL sensitivity criteria, were tested on the single-grain De results. Application of a fast ratio rejection criterion is able to successfully identify thermally unstable grains. A new rejection criterion based on dose saturation property was also applied to improve the age of one sample with a large De. Our dating results identify multiple phases of river valley aggradation in the upper Hunter catchment since late Marine Isotope Stage (MIS) 6; at ∼ 138 ka, ∼90–94 ka, ∼65 ka, ∼26 ka and ∼18 ka. The aggradational episodes of the terraces in the upper Hunter catchment are correlated with glacial or stadial periods since MIS 6. These phases of valley-floor aggradation are inferred to be a function of increased sediment supply during the cold periods resulting from strong periglacial activities in the adjacent Australian highlands.

    Original languageEnglish
    Pages (from-to)115-122
    Number of pages8
    JournalQuaternary Geochronology
    Volume49
    Early online date4 Jun 2018
    DOIs
    Publication statusPublished - Feb 2019

    Keywords

    • Fluvial terrace
    • Glacial episode
    • LGM
    • Single-grain OSL
    • Single-grain rejection criteria
    • Southeastern Australia

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