Mineralogy and mineral chemistry of oxide-facies manganese ores of the Postmasburg manganese field, South Africa

1997 ◽  
Vol 61 (405) ◽  
pp. 213-231 ◽  
Author(s):  
J. Gutzmer ◽  
N. J. Beukes
Keyword(s):  
South Africa ◽  
Mineral Chemistry ◽  
Early Diagenesis ◽  
Low Grade ◽  
Mineral Association ◽  
Rock Composition ◽  
Manganese Ores ◽  
Phase Chemistry ◽  
First Time ◽  
Metamorphic Alteration

AbstractThe diagenetic to very low-grade metamorphic manganese ores of the Postmasburg manganese field provide a unique example of oxide-facies manganese ores in a Palaeoproterozoic palaeokarst setting. The ores are composed mainly of braunite group minerals, including braunite, partridgeite and bixbyite, with rare braunite II and Ca-poor, silica-depleted braunite. Iron-poor partridgeite is distinguished from Fe-rich bixbyite and the occurrence of Ca-poor, silica-depleted braunite is reported for the first time. Braunite and partridgeite formed during early diagenesis but remained stable under greenschist facies metamorphic conditions. In contrast, bixbyite is apparently a product of metasomatic remobilisation under peak metamorphic conditions. It is suggested that local variations of the metamorphic mineral association reflect variations of the host rock composition and that they are not related to changing P-T conditions of metamorphic alteration, a model promoted by previous authors. The phase chemistry of braunite, braunite II and bixbyite is explained by the existing polysomatic stacking model for the braunite group. However, the chemical composition of partridgeite and Ca-poor, silica-depleted braunite can only be explained by introducing a distinct module layer, with partridgeite composition, to the existing polysomatic stacking model.

scholarly journals Downdip Development of the Ni-Cu-PGE-Bearing Mafic to Ultramafic Uitkomst Complex, Mpumalanga Province, South Africa

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 22
Author(s):  
Christoph Gauert ◽  
Armin Zeh
Keyword(s):  
South Africa ◽  
Age Determination ◽  
Mineral Chemistry ◽  
Low Grade ◽  
Mpumalanga Province ◽  
Icp Ms ◽  
Magmatic Reservoir ◽  
Sulphide Mineralisation ◽  
Ultramafic Unit ◽  
Magma Replenishment

The about 2055-Ma-old mafic to ultramafic Uitkomst Complex in the Mpumalanga Province of South Africa hosts the low-grade-large-tonnage Ni-Cu-PGE deposit, Nkomati. The complex is regarded to represent a satellite to the Bushveld Complex and a feeder to an eroded magmatic reservoir in the southeast. Aeromagnetic surveys and previous drilling indicated an overall northwestern-downdip extension of the complex, but the question is to what extent and in which expression can the complete intrusion be found under cover in the northwest? Answering this, a mineralogical, geochemical and geochronological investigation of a borehole intersection of the whole complex at Little Mamre was carried out, using petrography, XRF, EPMA and LA-ICP-MS U–Pb analyses of zircons for age determination. Although the total thickness of the rock units is larger than to the southeast, emplacement, litho- and mineral chemistry trends, expression of alteration mineralogy and style of sulphide mineralisation are similar. The amount of sulphide mineralisation is on average less than in the southeast. The upper ultramafic unit contains, more frequently, pegmatoidal sections, and the Chromitiferous Harzburgite unit has less massive chromitite layers than the southeastern parts of the complex, whereas the gabbro(-norite) units contain more interstitial liquid with late-stage minerals. The findings confirm that the anvil-shaped intrusion in cross section continues with increased thickness towards northwest at a shallow dip; although approaching the deeper part of the igneous reservoir, mineral compositions are partially more evolved. The overall mineralogical consistency downdip supports a situation of multiple magma replenishment along a flat-lying, northwest–southeast trending conduit, resulting in an evolved cumulus mineral assemblage in the upper part.

The Legal Status of Local Government in South Africa under the New Constitutional Dispensation

2018 ◽  
Vol 33 (2) ◽  
Author(s):  
Mbuzeni Mathenjwa
Keyword(s):  
South Africa ◽  
Local Government ◽  
Legal Status ◽  
Case Law ◽  
The Status ◽  
History Of ◽  
The Republic ◽  
First Time

The history of local government in South Africa dates back to a time during the formation of the Union of South Africa in 1910. With regard to the status of local government, the Union of South Africa Act placed local government under the jurisdiction of the provinces. The status of local government was not changed by the formation of the Republic of South Africa in 1961 because local government was placed under the further jurisdiction of the provinces. Local government was enshrined in the Constitution of the Republic of South Africa arguably for the first time in 1993. Under the interim Constitution local government was rendered autonomous and empowered to regulate its affairs. Local government was further enshrined in the final Constitution of 1996, which commenced on 4 February 1997. The Constitution refers to local government together with the national and provincial governments as spheres of government which are distinctive, interdependent and interrelated. This article discusses the autonomy of local government under the 1996 Constitution. This it does by analysing case law on the evolution of the status of local government. The discussion on the powers and functions of local government explains the scheme by which government powers are allocated, where the 1996 Constitution distributes powers to the different spheres of government. Finally, a conclusion is drawn on the legal status of local government within the new constitutional dispensation.

scholarly journals The Remarkable Antioxidant and Anti-Inflammatory Potential of the Extracts of the Brown Alga Cystoseira amentacea var. stricta

Marine Drugs ◽  
2020 ◽  
Vol 19 (1) ◽  
pp. 2
Author(s):  
Gina De La Fuente ◽  
Marco Fontana ◽  
Valentina Asnaghi ◽  
Mariachiara Chiantore ◽  
Serena Mirata ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
No Production ◽  
Low Grade ◽  
Raw 264.7 ◽  
Ros Scavenging ◽  
Ligurian Sea ◽  
Raw 264.7 Macrophages ◽  
Pharmaceutical Industries ◽  
Anti Inflammatory ◽  
First Time

Inflammation and oxidative stress are part of the complex biological responses of body tissues to harmful stimuli. In recent years, due to the increased understanding that oxidative stress is implicated in several diseases, pharmaceutical industries have invested in the research and development of new antioxidant compounds, especially from marine environment sources. Marine seaweeds have shown the presence of many bioactive secondary metabolites, with great potentialities from both the nutraceutical and the biomedical point of view. In this study, 50%-ethanolic and DMSO extracts from the species C. amentacea var. stricta were obtained for the first time from seaweeds collected in the Ligurian Sea (north-western Mediterranean). The bioactive properties of these extracts were then investigated, in terms of quantification of specific antioxidant activities by relevant ROS scavenging spectrophotometric tests, and of anti-inflammatory properties in LPS-stimulated macrophages by evaluation of inhibition of inflammatory cytokines and mediators. The data obtained in this study demonstrate a strong anti-inflammatory effect of both C. amentacea extracts (DMSO and ethanolic). The extracts showed a very low grade of toxicity on RAW 264.7 macrophages and L929 fibroblasts and a plethora of antioxidant and anti-inflammatory effects that were for the first time thoroughly investigated. The two extracts were able to scavenge OH and NO radicals (OH EC50 between 392 and 454 μg/mL; NO EC50 between 546 and 1293 μg/mL), to partially rescue H2O2-induced RAW 264.7 macrophages cell death, to abate intracellular ROS production in H2O2-stimulated macrophages and fibroblasts and to strongly inhibit LPS-induced inflammatory mediators, such as NO production and IL-1α, IL-6, cyclooxygenase-2 and inducible NO synthase gene expression in RAW 264.7 macrophages. These results pave the way, for the future use of C. amentacea metabolites, as an example, as antioxidant food additives in antiaging formulations as well as in cosmetic lenitive lotions for inflamed and/or damaged skin.

Implications for the age of South African Devonian rocks in which Tropidoleptus (Brachiopoda) has been found

1983 ◽  
Vol 120 (1) ◽  
pp. 51-58 ◽  
Author(s):  
A. J. Boucot ◽  
C. H. C. Brunton ◽  
J. N. Theron
Keyword(s):  
South Africa ◽  
North America ◽  
South African ◽  
Early Carboniferous ◽  
Fossil Plants ◽  
Geological Time ◽  
Marine Sedimentation ◽  
History Of ◽  
Near Shore ◽  
First Time

SummaryThe Devonian brachiopod Tropidoleptus is recognized for the first time in South Africa. It is present in the lower part of the Witteberg Group at four widely separated localities. Data regarding the stratigraphical range of the genus elsewhere, combined with information on recently described fossil plants and vertebrates from underlying strata of the upper Bokkeveld Group, suggest that a Frasnian or even Givetian age is reasonable for the lower part of the Witteberg Group. The recognition of Tropidoleptus in a shallow water, near-shore, molluscan association, at the top of the South African marine Devonian sequence, is similar to its occurrence in Bolivia, and suggests a common Malvinokaffric Realm history of shallowing, prior to later Devonian or early Carboniferous non-marine sedimentation. It is noteworthy that Tropidoleptus is now known to occur in ecologically suitable environments around the Atlantic, but is absent from these same environments in Asia and Australia. Tropidoleptus is an excellent example of dispersal in geological time — first appearing in northern Europe and Nova Scotia, then elsewhere in eastern North America and North Africa, followed by South America and South Africa, while continuing in North America.

Production of manganese (II) sulphate from low-grade manganese ores

2007 ◽  
Vol 14 (3) ◽  
pp. 105-108
Author(s):  
R. I. Razouk ◽  
S. K. Tobia ◽  
M. A. Messiha
Keyword(s):  
Low Grade ◽  
Manganese Ores

From the Madrasah to the Museum: The Social Life of the “Kietaabs” of Cape Town

2011 ◽  
Vol 38 ◽  
pp. 369-399 ◽  
Author(s):  
Saarah Jappie
Keyword(s):  
South Africa ◽  
Social Life ◽  
Living Room ◽  
Family Tree ◽  
Personal Journey ◽  
The Social ◽  
Arabic Script ◽  
Two Generations ◽  
Place Of Origin ◽  
First Time

Ebrahiem Manuel sits opposite me, about to embark upon his story. His living room is filled with material manifestations of his research: boxes overflowing with books and papers cover his entire sofa, newspapers and articles line the floor, and collages of images and texts hang on the walls and sit in the cabinets. It is clear that he is consumed by his passion for heritage, and his personal journey of discovery. He speaks in an animated, almost theatrical tone, raising and lowering his voice, stressing certain syllables, alive as he tells his story of “the ancient kietaabs.”The journey began in 1997, when Ebrahiem returned to South Africa after years at sea, working as a cook on shipping vessels. Upon his return, he began a quest to learn about his personal heritage, inspired by a dream he had had about his grandfather. This search led him to an oldkietaab, given to him by an elderly aunt. This was not the first time he had come across the old book; he remembered seeing it as a child, amongst other kietaabs, stored out of reach of the children, on top of his grandfather's wardrobe. It was inside this book that a possible key to his ancestors was to be found.This significant find was a range of hand-written inscriptions inside the book, in Arabic, English, and an unknown script. The Arabic script and its corresponding English transliteration read “Imaam Abdul Karriem, son of Imaam Abdul Jaliel, son of Imaam Ismail of Sumbawa.” Here was his family tree, starting from his great-grandfather and leading to two generations before him and, it seemed, their place of origin, the island of Sumbawa in eastern Indonesia. Ebrahiem then decided to go to Indonesia to solve what had become the mystery of “the ancient kietaab.”

Political Change in Rhodesia: The South Africa Factor

1975 ◽  
Vol 5 (4) ◽  
pp. 13-20
Author(s):  
Philip E. Chartrand
Keyword(s):  
South Africa ◽  
United Nations ◽  
Majority Rule ◽  
Political Change ◽  
The South ◽  
The United Nations ◽  
Liberation Movements ◽  
Minority Regime ◽  
Near Future ◽  
First Time

In December 1974, Ian Smith, the leader of the white minority regime in Rhodesia, announced for the first time since declaring his country’s independence from Britain in 1965 that his government was willing to begin direct negotiations with the African liberation movements seeking to achieve majority rule in Rhodesia. The prospect of such talks leading to an end to guerrilla fighting in Rhodesia and a termination of the United Nations authorized sanctions against the illegal Smith regime is dimmed by the fact that the Africans demand African rule for Rhodesia in the near future if not immediately, while Smith and his supporters have refused to consider such a development “in his lifetime.” Still the announcement constituted a step forward which few informed observers would have deemed likely even a few weeks before.

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