Morphometric Parameters of Krumbein Grain Shape Charts—A Critical Approach in Light of the Automatic Grain Shape Image Analysis

Abstract

Grain-shape analyses are essential in geological research because they provide the basis for genetic interpretations, including sedimentation conditions. The methods of visual evaluation used so far have been subjective, time-consuming and labour intensive. Automatic particle image analysis, including the methods used by the Morphology G3SE device, open up the possibility of mass and objective roundness analysis of mineral and organic particles. The article presents the results of measurements for the grain scale proposed by Krumbein in 1941, as this scale has been used in numerous sedimentological studies. The standard shapes were analysed using four parameters: High Sensitivity (HS) Circularity, Convexity, Solidity and Aspect Ratio. In the discussion, both the results and the grain-shape standards were critically assessed. The most important trends in the distribution of morphometric parameters of the scale are shown. On this basis, it was found that it is impossible to determine the parameter boundary values that would distinguish each class of grain roundness proposed by Krumbein. The conclusions propose criteria for the automatic differentiation of angular, subrounded and rounded grains, which could be a basis for describing the shape of mineral particles.

Characterization of Particle Shape with an Improved 3D Light Scattering Sensor (3D-LSS) for Aerosols

“…The Krumbein chart [28] was an early tool used to visually characterize the roundness of particles. The underlying principles are still used in commercial particle size analyzers, such as the Morphologi G3SE (Malvern Panalytical Ltd., Cambridge, UK) [29,30].…”

A Low-Cost, Repeatable Method for 3D Particle Analysis with SfM Photogrammetry

“…However, laser scanning and X-ray tomography techniques have been rarely used in sedimentary research, possibly due to costly and time-consuming methods of image acquisition and processing. Therefore, most of the recent geoscience research either uses 2D shape analysis [9,11,18,[36][37][38][39] or proposes techniques for 2D shape analysis [3,4,31,[40][41][42]. An alternative methodology that can be used for obtaining 3D data is photogrammetry.…”