On the reliability and comparability of laser diffraction grain size measurements of paleosols in loess records

Varga, György and Gresina, Fruzsina and Újvári, Gábor and Kovács, János and Szalai, Zoltán (2019) On the reliability and comparability of laser diffraction grain size measurements of paleosols in loess records. SEDIMENTARY GEOLOGY, 389. pp. 42-53. ISSN 0037-0738

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Laser diffraction grain size data and size distributions of paleosols are widely used in paleoenvironmental reconstructions as physicochemical alteration-related proxies of past changes of the sedimentary environment. Different laser diffraction devices, optical theories, and optical settings are being applied nowadays, and ignorance of several uncertainty factors and drawbacks of this indirect grain size characterization approach has led to poorly comparable and reproducible granulometric datasets. Here we present a detailed comparison of grain size results acquired by three state-of-the-art, widely used laser diffraction devices (Fritsch Analysette 22 Microtec Plus, Horiba Partica La-950 v2 and Malvern Mastersizer 3000). Grain size distributions were calculated using both the Fraunhofer and Mie scattering theories and a wide variety of optical settings (68 different complex refractive indices: 1.45–1.6–0.01i-1i) for 10 samples from loess-paleosol sequences of the Carpathian Basin. Our findings demonstrate that optical settings have significant effects on grain size distributions, especially for the finest fractions (clay and fine silt populations). Interestingly, the selection of laser diffraction devices was an even more deterministic factor in grain size characterization as revealed by network analyses. Clustering of bulk and size-fractionated grain size records was primarily determined by the device used, and also by the applied optical settings. At the same time, the real physical differences of samples were found to be deterministic exclusively for the sand-sized fraction. As such, these findings emphasize the importance of the accurate description of applied methodological details in research papers, as comparability and reproducibility of granulometric datasets cannot be ensured with a lack of information about instrumental conditions and settings.

Item Type: Article
Subjects: G Geography. Anthropology. Recreation / földrajz, antropológia, kikapcsolódás > GB Physical geography / leíró földrajz
Q Science / természettudomány > QE Geology / földtudományok
Depositing User: Dr. György Varga
Date Deposited: 30 Sep 2019 10:06
Last Modified: 30 Sep 2019 10:06

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