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Pan-African imprint on the early mid-proterozoic Richtersveld and Bushmanland sub-provinces near Eksteenfontein, Namaqualand, Republic of South AfricaBooth, Peter William King 27 March 2017 (has links)
The present investigation examines the relationship between the Proterozoic Richtersveld and Bushmanland Subprovinces in the westernmost part of the Namaqua Province, near Eksteenfontein, Republic of South Africa. There is a controversy about this relationship because isotopic data contrast with field evidence. On a regional scale the Richtersveld Subprovince is separated from the Bushmanland Subprovince by the northward-dipping Groothoek Thrust. North of the thrust the Richtersveld Subprovince is comprised of low grade volcano/ plutonic rocks of the Vioolsdrif Terrane and medium grade volcano sedimentary sequences of the Pella Terrane. Medium grade rocks of the Steinkopf Terrane (Bushmanland Subprovince) lie immediately south of the thrust. Late Proterozoic strata of the Stinkfontein Formation (Gariep Group) overlie the Namaqua Province in the west; Cambrian Nama Group outliers occur east of the Stinkfontein Formation. Isotopic data show that lithologies of the Richtersveld Subprovince formed between 2000 - 1730 Ma, whereas those of the Bushmanland Subprovince are younger. It is not clear whether the Namaqua metamorphic imprint (at 1200 - 1100 Ma), which is manifest in terranes south of the Groothoek Thrust, extended as far as the Vioolsdrif Terrane in the north. Early Proterozoic structural and metamorphic imprints are inferred to have been obliterated during this event. The westernmost part of the Namaqua Province was overprinted for a distance of 100 km from the coast, during the Pan-African event at 700 Ma and 500 Ma. An area measuring nearly 500 km2 , traversing the western extremity of the boundary between the Richtersveld and Bushmanland Subprovinces was mapped on a scale of 1:36,000. Field mapping was carried out with the aid of aerial photographs, whereas laboratory techniques included map compilation, structural analysis, X-ray diffractometry, geochemical (XRF) and electron microprobe analyses. Supracrustal units of the Richtersveld Subprovince are composed of quartzo-feldspathic gneisses, schists, and minor meta-pelites. Supracrustals of the Bushmanland Subprovince are less diverse than those of the Richtersveld Subprovince and have a disconformable relationship with them. Most intrusive rock-types are thick granitic sheets, except the Early Proterozoic Vioolsdrif Granodiorite which forms part of a batholithic pluton in the north. The Sabieboomrante adamellite gneiss, Kouefontein granite gneiss and Dabbieputs granite gneiss could not be correlated with lithologies commonly occurring in the Richtersveld and Bushmanland Subprovinces. They have been given the new rock names. Mafic and ultramafic rocks of the Klipbok complex occur along the strike of the Groothoek Thrust. They form part of the Richtersveld Subprovince.
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Co-operation for common pool resources an experimental perspectiveVollan, Björn January 2009 (has links)
Zugl.: Marburg, Univ., Diss., 2009
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Die invloed van die SA skolewet (1996) op dissipline in intermediêre skole in die Namakwa distrik van die Noord-Kaapprovinsie = The influence of the South African schools act (1996) on discipline in intermediate schools in the Namaqua district of the Northern Cape ProvinceHoorn, Lukas George 30 June 2006 (has links)
Die doel van hierdie studie van beperkte omvang is om inligting in te samel oor die probleem van dissipline soos dit manifesteer in Intermediêre Skole in die Namakwa Distrik van die Noord-Kaap Provinsie. Die aandag word toegespits op:
* wetgewing met betrekking tot dissipline in skole;
* soorte van probleme;
* faktore wat aanleiding gee tot probleme;
* maatreëls wat gebruik word om dissiplinêre probleme te hanteer en te voorkom.
Deur literatuurstudie word begrip en kennis verkry wat as agtergrond dien vir die kwalitatiewe ondersoek waardeur `n kontekstuele begrip verkry word van die ervaring van dissipline en probleme deur `n geselekteerde groep skoolhoofde van Intermediêre Skole in die Namakwa Distrik van die Noord-Kaapprovinsie. Ten slotte word voorstelle gemaak met die oog op die verbetering van `n komplekse situasie. / The aim of this study on a small scale is to gather information about the problem of discipline as manifested in Intermediate Schools in the Namaqua District of the Northern Cape Province. The attention is focused on:
* legislation in connection with discipline in schools;
* types of problems;
* factors that cause problems;
* measures to cope and prevent disciplinary problems. The study of literature provides understanding and knowledge that serves as background to the qualitative study by way of which a contextual understanding is developed of the experience of discipline and specific problems by a selected group of principals of Intermediate Schools in the Namaqua District of the Northern Cape Province. In conclusion proposals are made aimed at the improvement of a complex situation. / Educational Studies / M. Ed. (Educational Management)
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Die invloed van die SA skolewet (1996) op dissipline in intermediêre skole in die Namakwa distrik van die Noord-Kaapprovinsie = The influence of the South African schools act (1996) on discipline in intermediate schools in the Namaqua district of the Northern Cape ProvinceHoorn, Lukas George 30 June 2006 (has links)
Die doel van hierdie studie van beperkte omvang is om inligting in te samel oor die probleem van dissipline soos dit manifesteer in Intermediêre Skole in die Namakwa Distrik van die Noord-Kaap Provinsie. Die aandag word toegespits op:
* wetgewing met betrekking tot dissipline in skole;
* soorte van probleme;
* faktore wat aanleiding gee tot probleme;
* maatreëls wat gebruik word om dissiplinêre probleme te hanteer en te voorkom.
Deur literatuurstudie word begrip en kennis verkry wat as agtergrond dien vir die kwalitatiewe ondersoek waardeur `n kontekstuele begrip verkry word van die ervaring van dissipline en probleme deur `n geselekteerde groep skoolhoofde van Intermediêre Skole in die Namakwa Distrik van die Noord-Kaapprovinsie. Ten slotte word voorstelle gemaak met die oog op die verbetering van `n komplekse situasie. / The aim of this study on a small scale is to gather information about the problem of discipline as manifested in Intermediate Schools in the Namaqua District of the Northern Cape Province. The attention is focused on:
* legislation in connection with discipline in schools;
* types of problems;
* factors that cause problems;
* measures to cope and prevent disciplinary problems. The study of literature provides understanding and knowledge that serves as background to the qualitative study by way of which a contextual understanding is developed of the experience of discipline and specific problems by a selected group of principals of Intermediate Schools in the Namaqua District of the Northern Cape Province. In conclusion proposals are made aimed at the improvement of a complex situation. / Educational Studies / M. Ed. (Educational Management)
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New geochemical constraints on the genesis of the Gamsberg zinc deposit, Namaqualand Metamorphic Province, South AfricaFoulkes, Susan Elizabeth January 2014 (has links)
The base metal massive sulfide deposits of the Aggeneys-Gamsberg (A-G) District are hosted within the Mesoproterozoic Bushmanland Group of the Namaqua-Natal Metamorphic Complex in the Northern Cape Province of South Africa. The district displays an apparent eastward trend in the economic concentration of base metals (+ barite) from relatively Cu-Pb-rich, Ba-poor mineralisation at Black Mountain to Zn- and Ba-rich ores at Gamsberg. Base metal sulfides at Gamsberg are restricted to the so called Gams (Iron) Formation which comprises a sulfidic mineralized unit (“B”) enveloped within a sequence of meta-sedimentary units (“A” and “C”). The aim of the study was to shed further light on the genesis and chemical evolution of the sulfide mineralisation at Gamsberg in the context of the entire A-G District, by interrogating further the apparent district-wide trend in base metal distribution. The Gams Iron Formation was sampled and studied from one key drill core intersection (“G1”) which intersects the largest part of it as described elsewhere; a small number of additional samples from a second drill core (“G2”) complemented the main sample suite. Minerals that make up the silicate assemblages across the studied section include quartz, garnet, pyroxene, pyroxenoid, phyllosilicates, carbonates, amphiboles, oxides (chiefly magnetite) and graphite. In a stratigraphic context, the mineralogical variations conform directly to those documented in the relevant literature from the Gamsberg locality. These are coupled, where possible, with mineral-chemical profiles of selected silicate species which replicate those of bulk-rock compositions, particularly with respect to Mn, Fe and Ca in the upper C Unit of the studied section. These signals collectively track the characteristic transition from a terrigenous, siliciclastic sediment-dominated footwall to an exhalative sediment-dominated hanging wall to the sulfide mineralisation as also seen in similar deposits elsewhere, particularly with respect to the characteristic Mn-rich signature increasingly observed in the hanging wall C Unit. The foregoing suggests that the examined section faithfully records the interpreted primary stratigraphy of the deposits, despite the complex structural and metamorphic overprint that characterises the region. This facilitates a stratigraphic analytical approach on the sulfidic Unit B, through a combination of mineral-chemical and stable isotope analyses. Dominant sulfides in Unit B are sphalerite and pyrite, with lesser pyrrhotite and minor galena. Sphalerite shows high and generally invariant contents of Fe (mean 12.18wt%, as FeS) whereas Zn anti-correlates with Mn (mean 5.58wt%, as MnS). Isotopic analyses for S, Fe and Zn in hand-picked sphalerite and pyrite separates were used with a view to providing new evidence for chemical and isotopic variation within the sulfide ore-body in a vertical (i.e. stratigraphic) sense, discuss the implications thereof, and ultimately interpret the new data in light of similar existing data from the A-G District and elsewhere. The δ³⁴S data for pyrite (plus a single pyrrhotite grain) and sphalerite from both cores G1 and G2 show comparable compositional ranges between 22.9 and 30.4‰ and between 27 and 30.1‰ respectively. The δ⁵⁶Fe data for pyrite show a range between -1.85 and 0.19‰, whereas seven sphalerite separates have a very narrow range of δ⁶⁶Zn from 0.06 to 0.20‰. The atypically high sulfur isotope data reported in this study are interpreted to reflect sedimentary deposition of primary sulfide ore at Gamsberg from an isotopically highly evolved seawater sulfate source through large-scale Rayleigh fractionation processes. Thermogenic sulfate reduction is proposed to have been the main reductive mechanism from seawater sulfate to sulfide, given the absence of very low δ³⁴S data for sulfides anywhere in the A-G District. By contrast, the δ⁶⁶Zn values for sphalerite are for all intents and purposes invariant and very close to 0‰, and therefore suggest little Zn isotope fractionation from an original exhalative fluid source. On this evidence alone, Zn isotopes therefore appear to hold little promise as a proxy of the chemical and isotopic evolution of SEDEX deposits in space and time, although this can only be verified through further application in the broader A-G District and similar deposits elsewhere. The apparent decoupling of Zn and S isotopes in the Gamsberg sulfide deposit, however, points towards diverse sources of these two components, i.e. ascending metalliferous brines versus seawater respectively. Finally, pyrite δ⁵⁶Fe data do show a stratigraphic trend of generally declining values up-section, which are interpreted to reflect the influence of broadly coeval precipitation of isotopically heavy Fe-oxides on a broader-scale – now preserved as abundant magnetite through metamorphism. Further work on the iron isotope composition of silicate-and oxide-hosted Fe on a local-to-district scale will assist in testing this interpretation.
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