Abstract
Abstract A total of 92 representative sandstone samples of the Bredasdorp Basin in boreholes E-AH1, E-AJ1, E-BA1, E-BB1 and E-D3 have been investigated for their grain size characteristics. Grain size textural parameters and their cross plots, linear discriminate functions (LDFs), C–M (C = first percentile and M = median) diagram and log–probability plots were calculated and interpreted to understand the mode of transportation and hydrodynamic conditions and also to unravel the depositional environments of the sediments. The grain size textural parameters revealed that the Bredasdorp sandstones are unimodal, predominantly fine-grained, moderately well-sorted, mesokurtic and near symmetrical. The bivariate plots of grain size textural parameters indicate that the depositional environments had been influenced mainly by river/beach/coastal dune conditions. The LDF plots show that the sediments are turbidity current deposits in a shallow marine environment. The C–M diagram revealed that the studied sandstones were mainly deposited by traction currents and beach process. In addition, the grain size log–probability curves and C–M diagram show the predominance of suspension and saltation modes of sediment transportation. Based on the inter-relationship of the various statistical parameters, it is deduced that the Bredasdorp Basin are mainly shallow marine deposits with signature of beach and coastal river processes.
Highlights
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]
The calculated statistical parameters and their inter-relationship, linear discriminate function (LDF) analysis, C–M or Passega diagram and log–probability curves are used to highlight the several aspects of the transportation and depositional conditions the sediment grains underwent as well as relating them to particular depositional environments
The continental margin extending along the south coast of South Africa developed during the Mesozoic due to the break-up of Gondwana continent [15]
Summary
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 analysis reveals some essential evidences of transportation and depositional conditions [2,4] It is an essential parameter for textural classification of sedimentary rocks [5]. Grain size parameters of clastic rocks give detailed information on the sediment mode of transportation, sorting and depositional conditions prior to final induration [3,6]. The use of two component grain size variation diagrams, where one statistical parameter is plotted against another (i.e. skewness against kurtosis and skewness vs standard deviation) is supported by refs. The calculated statistical parameters and their inter-relationship, linear discriminate function (LDF) analysis, C–M or Passega diagram and log–probability curves are used to highlight the several aspects of the transportation and depositional conditions the sediment grains underwent as well as relating them to particular depositional environments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
