Quantitative characterization of grain shape: Implications for textural maturity analysis and discrimination between depositional environments

Abstract

Grain shape plays an important role in textural analysis of sedimentary grains. Textural analysis helps to determine the formation, transportation and deposition processes of sedimentary rocks. However, there is a lack of standardized methodology for quantitative characterization of grain shapes. The utility of fully automated image analysis for grain shape measurement is assessed in this paper. This research aimed to identify the most useful shape parameters for textural characterization of populations of grains and determine the relative importance of the parameters. A key aspect of this study is to determine whether, in a particular sedimentary environment, textural maturity of the samples can be ranked based on their grain shape data. Furthermore, discrimination of sedimentary depositional environments is explored on the basis of grain shape. In this study, 20 loose sediment samples from four known depositional environments (beach, aeolian, glacial and fluvial) were analysed using newly implemented automatic image analysis methods. For each sample, a set of 11 shape parameters were calculated for 200 grains. The data demonstrate a progression in textural maturity in terms of roundness, angularity, irregularity, fractal dimension, convexity, solidity and rectangularity. Furthermore, statistical analysis provides strong support for significant differences between samples grouped by environment and generates a ranking consistent with trends in maturity. Based on novel application of machine learning algorithms, angularity and fractal dimension are found to be the two most important parameters in texturally classifying a grain. The results of this study indicate that textural maturity is readily categorized using automated grain shape parameter analysis. However, it is not possible to absolutely discriminate between different depositional environments on the basis of shape parameters alone. This work opens up the possibility of detailed studies of the relationship between textural maturity and sedimentary environment, which may be more complicated than previously considered.

Understanding and managing suspended solids in intensive salmonid aquaculture: a review

“…This, however, is an oversimplification which does not represent a reality in which a variety of irregular shapes such as fibres, flocs, spheres and aggregates occur. A few studies have examined the shape of particles introduced from external sources such as river sediment (Blott & Pye 2008; Li et al 2016; Tunwal et al, 2018), while the first attempt at systematic shape analysis of internally derived organic particles in aquaculture systems was recently published (Becke et al 2020).…”

Fluvial or aeolian? Unravelling the origin of the silty clayey sediment cover of terraces in the Hanzhong Basin (Qinling Mountains, central China)

“…Dynamic image grain size and shape analysis was done with a Sympatec Qicpic in the Sediment Laboratory at VU Amsterdam. Grain shape analysis is used to determine transportation processes in aeolian sediments (Shang et al, 2017;Tysmans et al, 2009) or to determine the deposition environment (Tunwal et al, 2018). The Qicpic allows for the analysis of several million particles within the 2-500 μm range with a measurement time of 5 min.…”

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

“…These include methods based on both grainshape measurements [2,3] and visual evaluation, as proposed by Krumbein [4], Powers [5] and Cailleux [6,7]. The visual assessment of the grain shape is laborious and subjective, but it is widespread in the study of the characteristics of rocks and their genesis [8][9][10][11][12][13][14][15][16][17]. Genetic interpretation of sediments is often based on the results of sand (quartz) graincoating analyses.…”

“…Therefore, in interpreting the origin of sediments, the analysis of the shape of sand grains is essential. However, it should be emphasised that grain shapes in various sedimentary environments are similar, especially fluvial, aeolian and beach sediments, as well as glacial and weathered [14,19].…”

“…Today, several available devices automatically and objectively analyse the shape of grains [14][15][16][22][23][24][25]. One of them is the Morphologi G3SE.…”