Optical dating of relict sand wedges and composite-wedge pseudomorphs in Flanders, Belgium |
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| Authors: | JAN-PIETER BUYLAERT GUNTHER GHYSELS REW S MURRAY KRISTINA J THOMSEN DIMITRI VANDENBERGHE FRANS DE CORTE IRENÉE HEYSE PETER VAN DEN HAUTE |
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| Institution: | Laboratory of Mineralogy and Petrology, Geological Institute, Ghent University, B-9000 Gent, Belgium;;Geography Department, Geological Institute, Ghent University, B-9000 Ghent, Belgium;;Nordic Laboratory for Luminescence Dating, Department of Earth Sciences, Aarhus University, RisøNational Laboratory, DK-4000 Roskilde, Denmark;;RisøNational Laboratory, DK-4000 Roskilde, Denmark;;Laboratory of Analytical Chemistry, Institute for Nuclear Sciences, Ghent University, B-9000 Ghent, Belgium |
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| Abstract: | We report on quartz Optically Stimulated Luminescence (OSL) dating of the infill of 14 relict sand wedges and composite-wedge pseudomorphs at 5 different sites in Flanders, Belgium. A laboratory dose recovery test indicates that the single-aliquot regenerative-dose (SAR) procedure is suitable for our samples (measured to a given dose ratio 0.980 ± 0.005; n =139). Completeness of resetting of the wedge infill of two samples was confirmed by single-grain analyses. The suite of optical ages indicates that repeated thermal contraction cracking, degradation and infilling with wind-blown sediment appear to have been commonplace in Flanders during the Late Pleniglacial (Oxygen Isotope Stage 2; OIS2); more specifically, around the Last Glacial Maximum (LGM, ∼21 kyr ago) and the transition period between the LGM and the start of the Lateglacial (∼15 kyr ago). Optical dating at one site has revealed two significantly older wedge levels, the younger inset into the older; the younger wedge has an age of 36 ± 4 kyr (Middle Pleniglacial; OIS3), the older wedge 129 ± 11 kyr, which points to formation during the Late Saalian (OIS6). Our OSL ages of the wedges and host sediments bracket formation of the BGB (Beuningen Gravel Bed: a widespread deflation horizon in northwestern Europe) at between ∼15 and 18 kyr; this is in good agreement with previous OSL dating studies. We conclude that optical dating using quartz SAR OSL establishes an absolute chronology for these periglacial phenomena and allows secure palaeoenvironmental reconstructions to be made. |
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