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1	Genesis of karst-hosted manganese ores of the Postmasburg Manganese Field, South Africa with emphasis on evidence for hydrothermal processes / Genesis of karst-hosted manganese ores of the Postmasburg Manganese Field and the implications of related hydrothermal activity, Northern Cape, South Africa Fairey, Brenton John January 2014 (has links) The Postmasburg Manganese Field (PMF), located in the Northern Cape Province of South Africa, once represented one of the largest sources of manganese ore worldwide. However, the discovery of the giant manganese deposits of the Kalahari Manganese Field (KMF) led to the gradual decline in manganese mining activity in the PMF. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes in ore formation and metasomatic alteration is not addressed. The identification of an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in the PMF ores studied in this thesis, is indicative of the influence of hydrothermal activity. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for the majority of samples analysed through bulk-rock techniques. The discovery of a Ba-Mn arsenate/vanadate similar to gamagarite may also indicate that the hydrothermal fluid affecting the ores was not only alkali-rich but also probably contained some As and V. The fluid was likely to be oxidized and alkaline in nature and is thought to have been a mature basinal brine. Various replacement textures, particularly of Na- and Krich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as oreminerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and the deviation of their character from the pigeon-hole-type classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. The discovery of hydrothermallydeposited alkali-rich assemblages in the PMF and KMF provides grounding for further investigation into a possible regional-scale hydrothermal event at least re-constituting the ores. Some shortcomings in previous works include disregard for the highly variable nature of the PMF deposits, the effects of hydrothermal activity of the ores and the existence of stratigraphic discrepancies. This study provides a single, broad model for the development of all manganese deposits of the PMF. The source of metals is attributed to all formations that stratigraphically overly the Reivilo Formation of the Campbellrand Subgroup (including the Reivilo Formation itself). The main process by which metals are accumulated is attributed to karstification of the dolomites. The interaction of oxidized, alkaline brines with the ores is considered and the overlying Asbestos Hills Subgroup BIF is suggested as a potential source of alkali metals. Karst -- South Africa -- Postmasburg Petrology Mineralogical chemistry Geochemistry
2	Genesis and characteristics of the Wolhaarkop breccia and associated manganore iron formation 28 January 2009 (has links) M.A. / Hematized iron formation known as the Manganore iron formation is slumped into sinkhole structures in the Campbellrand Subgroup, Transvaal Supergroup, on the Maremane dome. These iron deposits are underlain by manganiferous breccias known as the Wolhaarkop Breccia. Known iron and manganese deposits of this type occur in an arc from Sishen in the north to Postmasburg in the south. The area is not being mined for manganese at the moment due to the relatively high grade of the Kalahari manganese field situated to the north of this area. The iron deposits, though, are some of the richest in the world. The aim is to establish the mode of origin for the Wolhaarkop Breccia. The Wolhaarkop Breccia is interpreted as being a residual ancient manganese wad from a karst environment in manganese rich dolostones of the Campbellrand Subgroup. This siliceous breccia contains authigenic megaquartz and angular poorly sorted clasts of chalcedony and quartz, set in a braunite-hematite matrix. Fluid inclusions in the authigenic quartz of the Wolhaarkop Breccia have been studied to establish the source of the fluid responsible for quartz precipitation in the Wolhaarkop Breccia, and indirectly, for the formation of the Wolhaarkop Breccia. Thermometric data was used to determine the maximum possible pT and depth conditions under which the quartz might have been precipitated. Fluid chemistry was determined using the bulk crush-leach method to shed some light on the fluid origin. It was established that the fluid responsible for chert recrystallization and precipitation of authigenic quartz and chalcedony had a meteoric source. Considering the results of the above-mentioned analysis, it was concluded that the iron and manganese deposits were formed during a cycle of uplift followed by subsidence. During the period of uplift, erosion in a karst environment and enrichment of iron formation in a supergene environment concentrated manganese as a manganese wad, and iron as a residual iron-oxide laterite. Meteoric water was the main fluid present during this period. Later, during a stage of subsidence, the Wolhaarkop Breccia underwent diagenesis and later lower greenschist-facies metamorphism. During a final stage of uplift the deposit was exposed to the atmosphere again, the dolostones were weathered away and the residual Manganore iron formation and Wolhaarkop Breccia were exposed to supergene alteration. Geology Manganese ores Iron ores Breccia Postmasburg (South Africa)
3	The displacement of a Northern Cape community : an anthropological research Becker, Elize 09 1900 (has links) Text in English with abstracts in English, Afrikaans and Tswana with keywords in English and Tswana / Displacement in the South African context is a complex and diverse phenomenon which is under-researched, particularly from the point of view of post-resettlement stress. The Meetse-a-tala community from Groenwater, Northern Cape, was resettled in 1964 and returned in 1999 to their ancestral land after a 25 year struggle to do so. The community anticipated that the land would present all the natural resources they had in 1964, but unfortunately, when they returned, the outlook seemed a lot different. / Verskuiwing in die Suid-Afrikaanse konteks is ‘n diverse en komplekse verskynsel wat nog nie voldoende nagevors is, veral vanuit die oogpunt van post-hervestigingsstres nie. Die Meetse-a-tala-gemeenskap van Groenwater in Noord-Kaap is in 1964 hervestig en het in 1999 teruggekeer na die land van hul voorouers na ‘n 25 jaarlange stryd om dit te bewerkstellig. Die gemeenskap het verwag dat die gebied weer al die natuurlike hulpbronne sou aanbied wat hulle in 1964 gehad het, maar ongelukkig, met hul terugkeer, het die vooruitsigte heel anders gelyk. / Tiragalo ya go fudusiwa ka dikgoka mo bokaong jwa Aforikaborwa e tlhagisa marara a a farologaneng ka ntlha ya dipatlisiso tse di lekanyeditsweng malebana le kgatelelo ya maikutlo e e amanang le morago ga go fudusiwa. Baagi ba Meetse-a-tala go tswa kwa Groenwater, kwa Kapabokone, ba itemogetse tiragalo ya go fudusiwa ka 1964 mme morago ga go kgaratlha dingwaga tse 25 go boela kwa lefatsheng la badimo ba bona, ba boetse ka 1999. Baagi ba ne ba solofetse gore lefatshe le tlaa ba neela ditlamelo tsotlhe tsa tlholego tse ba neng ba na natso fa ba tsamaya ka 1964, mme ka bomadimabe, e rile fa ba bowa, ba fitlhela le lebega le farologane thata. / Anthropology and Archaeology / M.A. (Anthropology) Displacement Resettlement Community Traditional leadership Leadership Community Property Association Tsantsabane Local Municipality Government Local authorities Anthropological research Social-cultural Youth Employment Post-resettlement stress Transport Electricity Basic services Symbolism Sacred Culture Meetse-a-tala Groenwater Kuruman Metsimanzi Postmasburg Groenwater Postmasburg Kuruman Phuduso ka dikgoka Phuduso baagi Boeteledipele jwa setso Boeteledipele Meetse-a-tala Metsimanzi Mokgatlho wa Baagi wa Dithoto Lekgotlatoropo la Selegae la Tsantsabane Puso Bothati jwa selegae Dipatlisiso tsa anteropoloji Setsoloago Bašwa Ditiro Dipalangwa Motlakase Ditirelo tsa motheo Bokao Boitshepo Setso 307.2096871

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