EGU2020-19218
https://doi.org/10.5194/egusphere-egu2020-19218
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Using the portable luminescence reader to assess the historical lateral mobility of river channels: preliminary promising results

Laurent Schmitt1, Timothée Jautzy1,2, Dominik Brill3, and Gilles Rixhon4
Laurent Schmitt et al.
  • 1Laboratoire Image Ville Environnement - CNRS - UMR 7362, Université de Strasbourg, Strasbourg, France
  • 2Département de biologie, chimie et géographie, Université du Québec à Rimouski, Rimouski, Québec, Canada
  • 3Institute of Geography, University of Cologne, Germany
  • 4Laboratoire Image Ville Environnement - ENGEES - CNRS - UMR 7362, Université de Strasbourg, Strasbourg, France

Timothée Jautzy1,2, Dominik Brill3, Laurent Schmitt1, Gilles Rixhon4

Obtaining robust chronological data on landforms and their related deposits together with constraining rates of earth surface processes have constantly represented a major challenge in Quaternary science. In the fluvial context, Optically Stimulated Luminescence (OSL) is particularly well-established but still faces several limitations. It notably requires expensive and time-consuming sample processing and measurement, frequently resulting in a poor spatial and stratigraphical distribution of sampling which may negatively impact the chronological information. To overcome this main limitation, a Portable OSL reader (POSL) has been recently developed (Sanderson & Murphy, 2010). It consists in directly capturing a luminescence signal (counts per seconds) on unprepared sediment samples. This technique is quick and affordable but, unlike conventional OSL, is not able to yield numerical age estimates.

This contribution explores POSL capacities to provide useful relative age information on alluvial sediments from the last centuries. We study and compare 42 samples collected from three alluvial profiles located in the floodplain of a gravelly-sandy mid-sized river: the Bruche (i.e. a sub-tributary of the Upper Rhine, France). POSL stimulations, including both blue and infra-red signals, are performed in combination with grain size analysis. We observe (i) an overall increase of signal intensity with increasing depth, (ii) a very good match between blue and IR signals and (iii) no systematic correlation between signal intensity and grain size. Whilst this last point must still be confirmed (i.e. signal intensity does not primarily depend on grain size), our preliminary results positively suggest that POSL is a promising tool to provide a relative chronology for very young alluvial sediments. Furthermore, it may also provide information on geomorphic processes. These results will be combined soon to numerical dating (OSL and 14C) and compared to outcomes of a planimetric analysis to thoroughly reconstruct the historical lateral mobility of the Bruche river.

How to cite: Schmitt, L., Jautzy, T., Brill, D., and Rixhon, G.: Using the portable luminescence reader to assess the historical lateral mobility of river channels: preliminary promising results, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19218, https://doi.org/10.5194/egusphere-egu2020-19218, 2020

How to cite: Schmitt, L., Jautzy, T., Brill, D., and Rixhon, G.: Using the portable luminescence reader to assess the historical lateral mobility of river channels: preliminary promising results, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19218, https://doi.org/10.5194/egusphere-egu2020-19218, 2020

Displays

Display file

Comments on the display

AC: Author Comment | CC: Community Comment | Report abuse

displays version 1 – uploaded on 01 May 2020
  • CC1: Comment on EGU2020-19218, Joel Roskin, 08 May 2020

    Dear Laurent

    I enjoyed seeing your fluvial application of the POSL.

    1. I was wondering what is the quartz-feldspar mineral ratio in your samples that give similar IRSL-BSL ratios?
    2. Can you provide additional insight from the jumpy signal pattern of the lower part of section? difference in bedoad/ fluvial power ?

    I am also studying with Lotem Robins and Noam Greenbaum (see presentation in upcoming drylands session aeolian-fluvial sections with POSL

    • AC1: Reply to CC1, Laurent Schmitt, 16 May 2020

      Dear Joel,

      Thanks for your interesting question.

      We have no idea of the quartz-feldspar ratio, as we didn't measured it. But this would obviously be a relevant measurement to do. We were indeed surprised (in good) to observe almost identical IRSL-BSL ratios.

      Our hypothese about the jumpy signal is that it corresponds to a "jumpy bleaching", possibly due to differences in bedload dynamics.

      Best regards,

      Laurent

  • CC2: Comment on EGU2020-19218, Harrison Gray, 08 May 2020

    Hi Laurent,

    Thanks for the interesting and enjoyable presentation. Do you have a sense of how fast POSL signals bleach in your river system? If not, would a bleaching experiment, where you expose a POSL sample to light for various times, give some insight?

     

    Thanks again!

    • AC2: Reply to CC2, Laurent Schmitt, 16 May 2020

      Hi Harrisson,

      Thanks you for your question.

      Your suggestion is very interesting. Sure, such test would be nice. We will try.

      Best regards,

      Laurent