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The petrology, petrography and geochemistry of anomalous borehole core sequences in the Highveld coalfield, South Africa : a case study for diatreme activity12 November 2012 (has links)
M.Sc. (Geology) / Three anomalous borehole core sequences from the north eastern Karoo Basin are examined. The boreholes are located up to 30 km from each other and are lithostratigraphically completely atypical for the Vryheid Formation, Ecca Group, Karoo Supergroup. The lithologies of the three boreholes are intensely brecciated for the most part, while all of the surrounding boreholes reveal normal stratigraphy; their sedimentary strata are normally horizontal with no faulting present. The only known disturbances to the Vryheid Formation in the study area are the occurrence of intrusive mafic dolerite sills and dykes, which are known to have been contemporaneous with and immediately following the eruption of the Drakensburg Group basaltic lavas. The borehole core lithologies are described in detail with reference to their textural, mineralogical and petrographic characteristics. Mineral and bulk rock chemical data are presented. Several modes of origin of the brecciated core sequences are considered, with the primary hypothesis that the brecciation is due to diatreme activity. A review of diatremes and their mode of emplacement is proposed with reference to their occurrence within the Karoo Igneous Province, as some diatremes in the Karoo are associated with dolerite sill emplacement. The isolated occurrences, lithologies, petrography, alteration and geochemistry of the sequences are used to argue that the Vryheid Formation, intersected in the form of the three anomalous boreholes, was disturbed by diatreme activity, which are genetically related to the late dolerite sill emplacement into the Karoo Supergroup rocks.
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Ouditproses van 'n kerklike welsynsorganisasie : n beskrywing van maatskaplike werkers se ervaringPretorius, Manda 06 1900 (has links)
Evaluation determines the impact of social services as well as job performance and
assures communities that social workers render effective services. Post audits are done
as part of performance management at the Christian Social Councils in the Highveld
Synodal Region.
The purpose of this research is to look at the experiences of social workers that had a
post audit to determine whether adjustments to improve the audit system are needed.
A qualitative approach with an exploratory, descriptive and contextual research design
was followed. Participants were identified according to the purposive sampling
method. Data was collected during semi-structured interviews. The data was analysed
and verified according to the models of Tesch (in Creswell, 2003) and Guba (in
Krefting, 1991), respectively, and processed in the research report. / Social Work / M. A. (Social Science)
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Ouditproses van 'n kerklike welsynsorganisasie : n beskrywing van maatskaplike werkers se ervaringPretorius, Manda 06 1900 (has links)
Evaluation determines the impact of social services as well as job performance and
assures communities that social workers render effective services. Post audits are done
as part of performance management at the Christian Social Councils in the Highveld
Synodal Region.
The purpose of this research is to look at the experiences of social workers that had a
post audit to determine whether adjustments to improve the audit system are needed.
A qualitative approach with an exploratory, descriptive and contextual research design
was followed. Participants were identified according to the purposive sampling
method. Data was collected during semi-structured interviews. The data was analysed
and verified according to the models of Tesch (in Creswell, 2003) and Guba (in
Krefting, 1991), respectively, and processed in the research report. / Social Work / M. A. (Social Science)
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The evaluation of various reseeding methods for restoring old croplands in the Highveld region of South AfricaVan Oudtshoorn, Frits 30 November 2007 (has links)
In spite of the relative simple vegetation structure, the Grassland biome has
surprisingly high species diversity. The Grassland biome is also the most
transformed biome in South Africa, with cultivation having the largest impact. When
croplands are abandoned, secondary succession leads to low diversity Hyparrhenia
hirta dominated grassland. A combination of two seed mixtures, two seeding
densities and two establishment methods was established in plots on a recently
abandoned cropland at Suikerbosrand Nature Reserve to evaluate their effect on
secondary succession. The rip plots, where more resources were available between
the rip lines, have shown higher densities of relic weeds as well as local perennials,
showing some progressive successional movement. However, Hyparrhenia hirta was
one of the non-sown perennials increasing in the rip plots. Hyparrhenia invasion and
relic weeds were best controlled in the plough plots. Although Hyparrhenia was
successfully controlled in plough plots, no secondary succession occurred in these
treatments. / Agriculture, Animal Health & Human Ecology / M. Tech. (Nature Conservation)
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The evaluation of various reseeding methods for restoring old croplands in the Highveld region of South AfricaVan Oudtshoorn, Frits 30 November 2007 (has links)
In spite of the relative simple vegetation structure, the Grassland biome has
surprisingly high species diversity. The Grassland biome is also the most
transformed biome in South Africa, with cultivation having the largest impact. When
croplands are abandoned, secondary succession leads to low diversity Hyparrhenia
hirta dominated grassland. A combination of two seed mixtures, two seeding
densities and two establishment methods was established in plots on a recently
abandoned cropland at Suikerbosrand Nature Reserve to evaluate their effect on
secondary succession. The rip plots, where more resources were available between
the rip lines, have shown higher densities of relic weeds as well as local perennials,
showing some progressive successional movement. However, Hyparrhenia hirta was
one of the non-sown perennials increasing in the rip plots. Hyparrhenia invasion and
relic weeds were best controlled in the plough plots. Although Hyparrhenia was
successfully controlled in plough plots, no secondary succession occurred in these
treatments. / Agriculture, Animal Health and Human Ecology / M. Tech. (Nature Conservation)
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