Grain size statistics and depositional pattern of the Ecca Group sandstones, Karoo Supergroup in the Eastern Cape Province, South Africa

Abstract

Grain size analysis is a vital sedimentological tool used to unravel the hydrodynamic conditions, mode of transportation and deposition of detrital sediments. In this study, detailed grain-size analysis was carried out on thirty-five sandstone samples from the Ecca Group in the Eastern Cape Province of South Africa. Grain-size statistical parameters, bivariate analysis, linear discriminate functions, Passega diagrams and log-probability curves were used to reveal the depositional processes, sedimentation mechanisms, hydrodynamic energy conditions and to discriminate different depositional environments. The grain-size parameters show that most of the sandstones are very fine to fine grained, moderately well sorted, mostly near-symmetrical and mesokurtic in nature. The abundance of very fine to fine grained sandstones indicate the dominance of low energy environment. The bivariate plots show that the samples are mostly grouped, except for the Prince Albert samples that show scattered trend, which is due to the either mixture of two modes in equal proportion in bimodal sediments or good sorting in unimodal sediments. The linear discriminant function analysis is dominantly indicative of turbidity current deposits under shallow marine environments for samples from the Prince Albert, Collingham and Ripon Formations, while those samples from the Fort Brown Formation are lacustrine or deltaic deposits. The C-M plots indicated that the sediments were deposited mainly by suspension and saltation, and graded suspension. Visher diagrams show that saltation is the major process of transportation, followed by suspension.

Sediment distribution on the continental shelf in relation to stream inputs and contamination: hydrodynamic, chemical, mineralogical, and sedimentological characteristics (Ligurian Sea, Italy)

“…According to this size distribution, sediment samples were poorly sorted (56%) or very poorly sorted (32%), with only the remaining 12% moderately sorted, which correspond to a probable deposition close to the source, a fast deposition, a diffused wave action, a concentrated deposition in the area, or an excessive volume of sediment (e.g. during floods or storm) (Baiyegunhi et al 2017 ; Watson et al 2013 ). The poorly sorting of sediments were also proved by the presence of more than a mode in the grain size distribution in 44% of samples, as shown in Fig.…”

Improved Packing Model for Functionally Graded Sand-Fines Mixtures—Incorporation of Fines Cohesive Packing Behavior

“…Based on the discussion above, higher porosity and permeability values are expected in sand-fines sediment mixtures deposited for example in aeolian environment when the sand particle size is fine (between 0.1 and 0.4 mm). Knowledge about sediment source and deposition environment can provide information about the expected particle size of the sediments and vice versa [78][79][80].…”

Textural characteristics, mode of transportation and depositional environment of the Cretaceous sandstone in the Bredasdorp Basin, off the south coast of South Africa: Evidence from grain size analysis

“…Grain size analysis is a useful tool used by geoscientists on siliciclastic sedimentary rocks in order to obtain a detailed understanding of the hydrodynamic condition and palaeoenvironmental features as well as reconstruct ancient sedimentary transport histories and sediment provenance [1,2]. Grain size distribution is one of the most significant properties of sediment particles because sizes of particles or grains in a particular deposit reveal their hydrodynamic energy and transportation processes [3].…”

“…Grain size distribution is one of the most significant properties of sediment particles because sizes of particles or grains in a particular deposit reveal their hydrodynamic energy and transportation processes [3]. Consequently, grain size analysis reveals some essential evidences of transportation and depositional conditions [2,4]. Also, it is an essential parameter for textural classification of sedimentary rocks [5].…”

“…Grain size analysis generates statistical parameters that include the graphic mean, standard deviation, kurtosis and skewness. Pertaining to grain size analysis, the log-probability plots and bivariate diagrams are the two main categories of graphical plots that are commonly used in environmental studies [1,2]. The use of two component grain size variation diagrams, where one statistical parameter is plotted against another (i.e.…”