Van Toer A. (pour l’équipe CliMag)
A laser granulometer Malvern MasterSizer 3000E, a joint LSCE instrument managed by the CliMag team, was acquired at the end of 2022 and installed in 2023 (Fig. 1).
It can be used to quickly measure the distribution of grain sizes between 0.1 and 1000 µm in all kinds of non-soluble samples that can be placed in the liquid phase. It is equipped with a large-volume dispersion tank (600 mL) for effective homogenisation of samples of natural origin such as sediments (marine and other) or soils.
With its wide range of sizes that can be analysed, it complements the granulometer acquired in 2005, which only covers the range between 0 and 63 µm.
Depending on the geographical location of the sites studied, granulometric analysis of the detrital fraction of marine samples can, among other things, tell us about variations in the intensity of deep ocean circulation in the past. Grain size varies according to distance from the source and/or the strength of the deep currents at the study site.
For example, a methodological study was carried out as part of Nathan Stevenard’s thesis (Stevenard et al., 2023, https://doi.org/10.1029/2022PA004500) to deconvolute the granulometry curves obtained on marine sedimentary series in the North Atlantic in order to separate the components linked to transport by deep currents from those linked, during the melting of icebergs, to the release of the terrigenous debris they contain, a component independent of deep currents.
This new instrument, which is quick and easy to use, is versatile and can therefore be used for any sediment study in marine or continental environments.
Fig. 1. Picture of the instrument (Malvern Mastersize 3000E).