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Textural characteristics, mode of transportation and depositional environment of the Stormberg Group in the Eastern Cape, South Africa: evidence from grain size and lithofacies analyses

Chima Priscilla, Baiyegunhi Christopher

Geologos

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2022

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Vol. 28, No. 1

61--78

EN

The Stormberg Group comprises the Molteno, Elliot and Clarens formations and is one of four stratigraphical groups that make up the Karoo Supergroup in South Africa. The group is the highest unit in the Karoo Basin, representing the final phase of preserved sedimentation. The major problem with the Stromberg Group is that the mode of transport, hydrodynamic energy conditions and depositional environment are still poorly understood. For the present paper, grain size and lithofacies studies on selected sandstones from the Molteno, Elliot and Clarens formations were performed so as to elucidate their textural characteristics, depositional processes, sedimentation mechanisms and hydrodynamic energy conditions and to discriminate different depositional environments. The statistical parameters of grain size distribution (mean grain size, standard deviation, skewness and kurtosis) show that the sandstones are predominantly unimodal, fine grained, moderately well sorted, mesokurtic and near symmetrical. The bivariate diagrams of the aforementioned statistical parameters demonstrate that river and aeolian dune had the greatest impact on the depositional environments. Likewise, the C-M pattern (Passega diagram) shows that the sandstones were mostly deposited through tractive current process. Furthermore, the C-M diagram reveals the prevalence of rolling, suspension and graded suspension modes of sediment transportation. Seventeen sedimentary lithofacies were identified and grouped into seven lithofacies associations. These lithofacies associations indicate braided channel, overbank and swamp deposits for the Molteno Formation, alluvial fan/floodplain and playa deposits for the Elliot Formation and aeolian deposits for the Clarens Formation.

2

Parametry teksturalne analcymu powstałego przy użyciu 1M roztworu NaOH

Adamczyk Z., Makosz E.

Zeszyty Naukowe. Inżynieria Środowiska / Uniwersytet Zielonogórski

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2015

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nr 158 (38)

5--12

PL

W pracy przedstawiono parametry teksturalne materiału zeolitowego, powstałego w wyniku hydrotermalnej syntezy popiołu lotnego. Do zeolityzacji wykorzystano popiół lotny w ilości 200 g, zawierający kwarc, mullit, składniki nieprzezroczyste, szkliwo oraz w podrzędnej ilości hematyt i nieprzepaloną substancję organiczną, a proces syntezy prowadzono przy użyciu 1M roztworu NaOH. W produktach po syntezie zidentyfikowano analcym, jako dominujący zeolit, z domieszką innego zeolitu - kankrynitu. Parametry teksturalne otrzymanego materiału zeolitowego wskazują, że jest to materiał mezoporowaty. Porównanie parametrów teksturalnych otrzymanego materiału zeolitowego zbudowanego z analcymu z domieszkami kankrynitu z innym materiałem zeolitowym otrzymanym w wyniku podobnej syntezy, gdzie obecny był tylko jeden zeolit – analcym wskazuje, że obecność kankrynitu wpływa na te parametry, jednakże nie zmienia to typu adsorbentu ze względu na wielkość porów.

EN

The paper presents the textural parameters of the zeolite material, resulting from hydrothermal synthesis of fly ash. For the zeolitization fly ash was used, in an amount of 200g, containing quartz, mullite, opaque components, glaze and in the subordinate amount hematite and not burnt organic substance; the process for the synthesis was conducted using 1 M solution of NaOH. The product identified in the synthesis was analcime, as dominant zeolite, with admixture of other zeolite - kankrynite. Textural parameters of obtained zeolite material indicate that material is mesoporous. Comparison of the textural parameters of obtained zeolite material built up of analcime with admixture of kankrynite with another zeolite material obtained from a similar synthesis, where there was present only one zeolite – analcime, indicates that the presence of kankrynite affect these parameters, however it does not change the type of the adsorbent due to the size pores.

3

Alternative interpretations of grain-size data from Quaternary deposits

Mycielska-Dowgiałło Elżbieta, Ludwikowska-Kędzia Małgorzata

Geologos

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2011

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Vol. 17, No. 4

189--203

EN

Several possibilities to present and to interpret the results of granulometric analyses of Quaternary fluvial, aeolian, glacial and wash-out slope deposits were investigated. Attention is paid particularly to the cumulative curves at a probability scale and the frequency curves, and it is shown how these curves can help to determine the sedimentary environment. The inclination of the cumulative curves in the part of the maximum proportion of a particular grain size appears significant. It appears possible to obtain information on the density and dynamics of the transporting medium from the course of the cumulative curves (inclination and spread of grain size). The examination of textural parameters allows to draw regression lines characteristic of both deposits from various sedimentary environments and deposits from one single environment but with different histories as to their transport dynamics.