Geochemical, mineralogical and tenor variation studies were carried out on the cores from UMT040, UMT064 and UMT063, located in the Flatreef on Turfspruit, in the southern sector of the Platreef. The investigation comprised three objectives (1) to identify controls on mineralisation in the upper section of the Platreef, (2) to construct a 3D PGE tenor model, and (3) to test whether the new geological interpretation on Turfspruit correlates with the eastern and western limbs of the Bushveld Complex. The above-mentioned holes were used for geochemical analyses of major and trace elements; and UMT064 was also used for orthopyroxene microprobe analyses. For construction of the tenor model, a total of 276 drill holes were used. The distance between drill holes for geochemical studies is 145 m and 175 m respectively; and for the tenor model is approximately 100 m. The outcomes of the study have demonstrated that the upper section of the Platreef comprise at least four lithological units i.e. the topmost portion of T1, lowermost portion of T1, T2 Upper and T2 Lower that can be interpreted to have been formed by four separate pulses of magma. Considering the possibility of the T2 Lower being metamorphosed calc-silicates, this reduces the number of magma pulses to three. This is supported by the mineralogy, geochemical content and tenor variations. The T1 is made up of an orthopyroxenite (feldspathic in places), the T2 Upper comprised a pegmatoidal orthopyroxenite (also feldspathic in places) and the T2 Lower is made up of a harzburgite. High grade PGE, Ni and Cu mineralisation was found to occur within two zones in the upper section of the Platreef i.e. the T1m and T2 (Upper and Lower). Mineralisation occurs in the form of base metal sulphides such as pyrrhotite, pentlandite and chalcopyrite; and PGEs are dominated by amphoterics (PGE-arsenides, tellurides, antimonides and bismuthinides). These amphoterics are associated with base metal sulphides. The sulphides in both the T1m and T2 are interstitial. PGE minerals such as michenerite, sperrylite, hollingworthite and cooperite are present in the study area. In the T2, an increase in sulphide content and PGE grades are generally associated with the presence of the “main” chromitite stringer/ seam at the contact between a feldspathic pyroxenite (T1) and the coarse-grained to pegmatoidal pyroxenite (T2 Upper). Several other chromitites might be present above and below this contact, and it has been noted that not all of those chromitites are associated with an increase in sulphide content and higher PGE grades. PGE grades were found to be higher in T2 Upper than in T2 Lower, whereas, the base metals (particularly Ni) are generally higher in T2 Lower. In the T1m, mineralisation occurs close to the contact between the feldspathic pyroxenite and orthopyroxenite, but only the orthopyroxenite hosts the sulphides. Chromitite stringers rarely occur in the T1m. Where present, they generally occur at the top of the mineralised zone. The sulphides in both the T1m and T2 are thought to have resulted from separate and different processes. Those in the T1m are thought to have resulted from a fractional segregation process, whereas the sulphides in the T2 were thought to have been emplaced in bulk or as a mush. The 3D PGE tenor model has demonstrated that the tenor in both the T1 and T2 are higher than previously thought for the northern limb of the Bushveld Complex. Tenors in the T1 reach up to 700 ppm, whereas tenors of about 1000 ppm were recorded in the T2. These tenors are comparable to the tenors measured from the sulphide melt inclusions elsewhere in the northern limb. Tenors are the highest in the northwestern part of Turfspruit and they gradually decrease towards the southeast. Both the T1 and T2 are dominated by a tenor of about 100 ppm. In the T1, a tenor of 250 ppm is dominant in the northwestern and southeastern parts of the study area, whereas in the T2 it is only dominant in the northwestern part. Vertical variation in tenors has shown that the tenors are the highest in the topmost portion of the T1 and at the top of T2 Upper (below the T1-T2 contact). The T1 has been found to be comparable with the Merensky Reef due to the following: (a) similarities with respect to major and trace element compositions of whole rock analyses; (b) Cr/MgO ratios which are greater than 80; and (c) similarities in the pyroxene content excluding the MgO/((MgO)+FeO) ratio and CaO contents; and in the PGE tenor of the sulphides. In addition, the T1 has many of the characteristics of the model proposed by Naldrett et al (2009) for the formation of the Merensky Reef in the western Bushveld. However, the differences between the T1 and the Merensky Reef were also noted i.e. the MgO/((MgO)+FeO) ratios in this study are lower (averaging 0.71) than the Mg# reported for the Merensky Reef (Mg#78-83), the upper Critical Zone (Mg#78-84) and elsewhere in the Platreef north of Turfspruit. The CaO levels (representing the wollastonite component of the orthopyroxene) at Turfspruit are higher (>2 wt %) compared to the Merensky Cyclic Unit and other parts of the northern limb where the CaO levels are below 2 wt %. This is an indication that the pyroxene composition at Turfspruit is more evolved compared to the Merensky Reef.

Le Platreef est une formation noritique contenant des minéralisations en Éléments du Groupe du Platine. Elle se situe en bordure de la partie septentrionale du complexe du Bushveld. Afin de définir les spécificités de cette unité marginale, nous avons tout d'abord étudié des échantillons pouvant servir de point de comparaison : ils proviennent d'une zone centrale de l'intrusion, le forage de Bellevue. Les données en isotopie de l'oxygène indiquent des valeurs de δ18O proches de 6,5 à 7 ‰ et homogènes à travers la pile magmatique. Ces valeurs, plus lourdes de 1 à 1,5 ‰ que celles des autres produits issus du manteau du Kaapvaal, sont l'indice d'une contamination crustale à l'échelle de tout le complexe. L'isotopie de l'hydrogène et les teneurs en eau témoignent de cumulats peu ou pas altérés. <br /><br />Sur la base de critères pétrographiques et géochimiques, le Platreef apparaît beaucoup plus affecté par des phénomènes d'assimilation et de circulations de fluides. Il a été échantillonné sur 4 sites, en contact avec différentes roches encaissantes : granites Archéens, dolomies, quartzites et cornéennes. Les xénolithes calco-silicatés sont omniprésents dans ces portions du Platreef. Une contamination par des liquides de fusion partielle du granite est également mise en évidence. Les cumulats les plus affectés par l'altération se trouvent au contact des granites, qui constituent l'encaissant le plus fracturé. <br /><br />À l'échelle du complexe, le rapport fluide/roche des interactions est très faible : les circulations ont été confinées à des chenaux préférentiels. Les caractéristiques isotopiques et géochimiques des fluides ne correspondent pas à celles des eaux météoritiques. Ils étaient probablement originaires des formations sédimentaires proches et ont été expulsés lors de la perturbation thermique due à la mise en place des magmas du Bushveld. Ils contenaient du chlore et du CO2 leur permettant de jouer un rôle dans la distribution des PGE.

South Africa is a megadiverse country, and its biodiversity is endangered by population pressure and the development needs of a developing country. In order to address the rapid decline in biological diversity, biodiversity planning has become a key focus area that aims at identifying priority areas for species and ecosystem conservation within and outside of formally protected areas. Plant conservation hotspots are identified by the quantification of indicator taxa such as plant taxa richness, rarity and endemism. But the urgent and enormous task of biodiversity assessment for conservation planning requires that we make most of what we know. Therefore, this study seeks to make a contribution by finding new ways of biodiversity pattern estimation from the extrapolation of incomplete sets of plant species distribution data at the Quarter Degree Grid level. Incomplete sampling across the grids of a study area results in false records of species absence and thus a biased biodiversity estimation. As a possible solution, plant distribution data for the western Central Bushveld Bioregion has been standardized using two profiles, namely the ‘Centroid Grid’ and ‘Integrated Grid’ profile. The former involves the strengthening of under-sampled grids by extrapolating species occurrences from three adjacent grids with the most similar vegetation units, whereas the latter integrates phyto-diversity data for the four grids intersecting at each grid reference point. Standardized data has proved to provide a means to counter the bias in plant diversity data linked to Quarter Degree Grids by a) strengthening of under-sampled grids and b) visibly smoothing out the gaps between under- and well-sampled grids, which resulted in improved biodiversity estimation for more representative spatial biodiversity modelling. Interpolation created geo-referenced polygons for more explicit use in the identification of areas of conservation concern at bioregional scale. However, well-sampled grids still dominate the outcomes of the analysis by creating spatial sampling bias. Therefore, this approach to calibrate Quarter Degree Grid resolution of spatial data is an additional attempt to achieve more representative mapping of biodiversity patterns, which is a prerequisite for strategic conservation planning for ‘living landscapes’. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012

South Africa is a megadiverse country, and its biodiversity is endangered by population pressure and the development needs of a developing country. In order to address the rapid decline in biological diversity, biodiversity planning has become a key focus area that aims at identifying priority areas for species and ecosystem conservation within and outside of formally protected areas. Plant conservation hotspots are identified by the quantification of indicator taxa such as plant taxa richness, rarity and endemism. But the urgent and enormous task of biodiversity assessment for conservation planning requires that we make most of what we know. Therefore, this study seeks to make a contribution by finding new ways of biodiversity pattern estimation from the extrapolation of incomplete sets of plant species distribution data at the Quarter Degree Grid level. Incomplete sampling across the grids of a study area results in false records of species absence and thus a biased biodiversity estimation. As a possible solution, plant distribution data for the western Central Bushveld Bioregion has been standardized using two profiles, namely the ‘Centroid Grid’ and ‘Integrated Grid’ profile. The former involves the strengthening of under-sampled grids by extrapolating species occurrences from three adjacent grids with the most similar vegetation units, whereas the latter integrates phyto-diversity data for the four grids intersecting at each grid reference point. Standardized data has proved to provide a means to counter the bias in plant diversity data linked to Quarter Degree Grids by a) strengthening of under-sampled grids and b) visibly smoothing out the gaps between under- and well-sampled grids, which resulted in improved biodiversity estimation for more representative spatial biodiversity modelling. Interpolation created geo-referenced polygons for more explicit use in the identification of areas of conservation concern at bioregional scale. However, well-sampled grids still dominate the outcomes of the analysis by creating spatial sampling bias. Therefore, this approach to calibrate Quarter Degree Grid resolution of spatial data is an additional attempt to achieve more representative mapping of biodiversity patterns, which is a prerequisite for strategic conservation planning for ‘living landscapes’. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012

The presence of trace transition metal species in the atmosphere can be attributed to the emission of particulate matter into the atmosphere by anthropogenic activities, as well as from natural sources. Trace metals emitted into the atmosphere can cause adverse health–related and environmental problems. At present, limited data exists for trace metal concentrations in South Africa. In this investigation, the general aim was to determine the concentrations of trace metals in atmospheric aerosols in the industrialised western Bushveld Igneous Complex, as well as to link the presence of these species in the atmosphere to possible sources in the region. The measurement site was placed in Marikana, a small rural town situated 35 km east from Rustenburg in the North West Province of South Africa. It is surrounded by numerous industrial and metallurgical operations. MiniVolumeTM samplers and Teflon® filters (2 ;m pores) were utilised to collect PM2.5 and PM10 particulate samples. The MiniVolumeTM samplers were programmed to filter 5 litres of air per minute for 12 hours per day, over a six–day period. The starting time for sampling was altered every six days, in order to obtain both day and night samples. Sampling was performed for a period of one year. The collected samples were chemically analysed with inductively coupled plasma mass spectroscopy (ICP–MS). Surface analysis of the sampled filters was performed with a scanning electron microscope (SEM) in conjunction with energy–dispersive spectroscopy (EDS). The dataset was also subjected to factor analysis in an attempt to identify possible sources of trace metal species in the atmosphere. The concentrations of 27 trace metals (Be, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Pd, Cd, Ba, Pt, Au, Hg, Tl, Pb, U) were determined. Pd, Hg, Tl, U, Ca, Co, As, Cd, Ba and Au were above the detection limit 25% or less of the time during the sampling period. With the exception of Ni, none of the trace metals measured at Marikana during the sampling period exceeded local and international standards. Higher Ni levels were possibly due to base metal refining in the region. Pb, which is the only metal species that has a standard prescribed by the South African Department of Environmental Affairs (DEA), did not exceed any of the standards. It is also significant to refer to Hg that was below the detection limit of the analytical instrument for the entire sampling period. The impact of meteorological conditions revealed that wet removal of atmospheric PM10 trace metals was more significant than the wind generation thereof. During the dry months, the total trace metal concentrations in the PM10 fraction peaked, while PM10 particles were mostly washed out during the wet season. Wind speed showed an unexpected inverse pattern compared to wet deposition. A less significant seasonal trend was observed for the trace metal concentrations in the PM2.5 fraction, which was attributed to a faster replenishment of smaller particles into the atmosphere after rain events. Separation of trace metal concentrations into PM10–2.5 and PM2.5 fractions indicated that 79% of the total trace metal levels that were measured were in the PM2.5 fraction, which indicated a strong influence of industrial and/or combustion sources. Fractionalisation of each of the trace metal species detected showed that for each metal species, 40% and more of a specific metal was in the PM2.5 fraction, with Cr, V, Ni, Zn and Mn occurring almost completely in the PM2.5 fraction. Surface analysis with SEM supported results from the chemical analysis, which indicated that a large fraction of the particles was likely to originate from anthropogenic activities and from wind–blown dust. SEM–EDS also detected nonmetallic S that is usually associated with the Pt pyrometallurgical industry that is present in the western Bushveld Igneous Complex. Correlations between Cr, V, Ni, Zn and Mn revealed that the main sources of these species were pyrometallurgical industries. Explorative factor analysis of the unprocessed and Box–Cox transformed data for all 27 metals detected, resolved four meaningful emission sources, i.e. crustal, vanadium related, base metal related and chromium related. Comparison of trace metal species to other parameters measured (e.g. CO, BC) also indicated pyrometallurgical activities and wind–blown dust to be the main sources of trace metals in this region. / Thesis (M.Sc. (Chemistry))--North-West University, Potchefstroom Campus, 2011.

The presence of trace transition metal species in the atmosphere can be attributed to the emission of particulate matter into the atmosphere by anthropogenic activities, as well as from natural sources. Trace metals emitted into the atmosphere can cause adverse health–related and environmental problems. At present, limited data exists for trace metal concentrations in South Africa. In this investigation, the general aim was to determine the concentrations of trace metals in atmospheric aerosols in the industrialised western Bushveld Igneous Complex, as well as to link the presence of these species in the atmosphere to possible sources in the region. The measurement site was placed in Marikana, a small rural town situated 35 km east from Rustenburg in the North West Province of South Africa. It is surrounded by numerous industrial and metallurgical operations. MiniVolumeTM samplers and Teflon® filters (2 ;m pores) were utilised to collect PM2.5 and PM10 particulate samples. The MiniVolumeTM samplers were programmed to filter 5 litres of air per minute for 12 hours per day, over a six–day period. The starting time for sampling was altered every six days, in order to obtain both day and night samples. Sampling was performed for a period of one year. The collected samples were chemically analysed with inductively coupled plasma mass spectroscopy (ICP–MS). Surface analysis of the sampled filters was performed with a scanning electron microscope (SEM) in conjunction with energy–dispersive spectroscopy (EDS). The dataset was also subjected to factor analysis in an attempt to identify possible sources of trace metal species in the atmosphere. The concentrations of 27 trace metals (Be, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Pd, Cd, Ba, Pt, Au, Hg, Tl, Pb, U) were determined. Pd, Hg, Tl, U, Ca, Co, As, Cd, Ba and Au were above the detection limit 25% or less of the time during the sampling period. With the exception of Ni, none of the trace metals measured at Marikana during the sampling period exceeded local and international standards. Higher Ni levels were possibly due to base metal refining in the region. Pb, which is the only metal species that has a standard prescribed by the South African Department of Environmental Affairs (DEA), did not exceed any of the standards. It is also significant to refer to Hg that was below the detection limit of the analytical instrument for the entire sampling period. The impact of meteorological conditions revealed that wet removal of atmospheric PM10 trace metals was more significant than the wind generation thereof. During the dry months, the total trace metal concentrations in the PM10 fraction peaked, while PM10 particles were mostly washed out during the wet season. Wind speed showed an unexpected inverse pattern compared to wet deposition. A less significant seasonal trend was observed for the trace metal concentrations in the PM2.5 fraction, which was attributed to a faster replenishment of smaller particles into the atmosphere after rain events. Separation of trace metal concentrations into PM10–2.5 and PM2.5 fractions indicated that 79% of the total trace metal levels that were measured were in the PM2.5 fraction, which indicated a strong influence of industrial and/or combustion sources. Fractionalisation of each of the trace metal species detected showed that for each metal species, 40% and more of a specific metal was in the PM2.5 fraction, with Cr, V, Ni, Zn and Mn occurring almost completely in the PM2.5 fraction. Surface analysis with SEM supported results from the chemical analysis, which indicated that a large fraction of the particles was likely to originate from anthropogenic activities and from wind–blown dust. SEM–EDS also detected nonmetallic S that is usually associated with the Pt pyrometallurgical industry that is present in the western Bushveld Igneous Complex. Correlations between Cr, V, Ni, Zn and Mn revealed that the main sources of these species were pyrometallurgical industries. Explorative factor analysis of the unprocessed and Box–Cox transformed data for all 27 metals detected, resolved four meaningful emission sources, i.e. crustal, vanadium related, base metal related and chromium related. Comparison of trace metal species to other parameters measured (e.g. CO, BC) also indicated pyrometallurgical activities and wind–blown dust to be the main sources of trace metals in this region. / Thesis (M.Sc. (Chemistry))--North-West University, Potchefstroom Campus, 2011.

M.Sc. / This study focuses on the Merensky Reef (MR) occurring within the Two Rivers Platinum mine property in the farm Dwarsriver 372 KT, on the Southern sector of the Eastern Limb of the Bushveld Complex. Five MR exploratory drill core intersections were obtained. Petrographic and mineral chemical characteristics of these drill core samples focused on the characterization of minerals like clinopyroxene, orthopyroxene, plagioclase, chromite and olivine. Data of the cryptic variation of orthopyroxene, plagioclase and chromite, from a 10 m interval (approximate thickness of the section studied); from footwall through the MR to the hangingwall lithologies at Dwarsriver are described in this study. Locally the vertical cryptic variation of these minerals is broadly consistent with regional trends of the RLS. The lateral variation (i.e. along strike) is less pronounced; however, locally these minerals appear to be chemically evolving moving to the south of the property. Footwall orthopyroxene compositions vary from a minimum of En66 and reach a maximum of En84. Those of the MR range from En71 to En85. Hangingwall orthopyroxene compositions range from En60 and reach a maximum of En80. Plagioclase compositions in the footwall units range from a minimum of An69 and reach a maximum of An85. Those of the MR range from a minimum of An35 to a maximum of An84. This wide range in plagioclase compositions is believed to be as a result of the increased presence of fluids within the MR interval. The hangingwall plagioclase compositions range from An64 to An84. By analogy of the Western Limb, where the lithologies of the Northwestern sector are believed to be proximal to the feeder of this limb; the local lateral variation in the present study suggests that the lithologies of either the Central or Western sectors are most probably proximal to the feeder for the Eastern Limb. PGM assemblages associated with and adjacent to the MR chromitite stringers were evaluated using an MLA. Data obtained from this technique is in broad agreement with regional studies of the MR. With the aid of wholerock PGE assays the MLA technique has proven to be a powerful tool in evaluating PGM assemblages relatively quickly, from a few carefully selected samples. The mineralogical associations of the PGM with the gangue and host minerals have shown three main associations. These are the associations of chromite, BMS and silicates with the PGM, of which the base metal sulfide (BMS) association is remarkable given that these have a relatively low modal abundance. The relatively high mineralogical association of the BMS with PGM has been explained by a model involving a base metal sulfide liquid which possibly scavenged chalcophile and siderophile elements. Chromite chemistry and modal analyses of MR secondary silicate phases, which peak adjacent to the chromitite stringers, suggests elevated fluid overprinting within and adjacent to the chromitite stringers. The upper chromitite stringers, however, have higher abundances of PGM phases that are believed to be secondary in origin relative to the basal chromitite stringers. Generally the PGM associated with the upper chromitite stringers are also bigger in size averaging 70 μm as opposed to 27 μm for those associated with the basal chromitite stringers. The increase in grain size of the PGM along with the higher modal abundance of secondary PGM phases associated with the upper stringers is believed to be as a result of fluids. These fluids although affecting both the upper and basal chromitite stringers, appear to have had a relatively higher influence on the upper chromitite stringers. The most common PGMs encountered in this study are isoferroplatinum, sperrylite, michenerite, maslovite, cooperite, laurite and braggite.

Boreholes NG1 and NG2 were drilled on the farm Nooitgedacht 406 KQ to intersect the lower Critical and lower Zones of the western Bushveld Complex. The aim of this study is to describe the textural features and chemical characteristics of the olivine-bearing rocks in the intersections, as determined by petrographic studies, XRF analysis and microprobe analysis. The olivine-bearing rocks are dunites, harzburgites and olivine pyroxenites. They comprise olivine and orthopyroxene, with minor chromite, clinopyroxene and plagioclase, and their textures vary between adcumulate, mesocumulate and poikilitic. The sequence intersected can be broadly correlated with that in the eastern Bushveld Complex. Of the whole-rock inter-element ratios, the MMF (MgO)/[MgO+FeO])ratio is the clearest indicator of cyclicity. The olivine-rich rocks are more primitive than the associated rocks, and seem to become more primitive with height in most intervals. The plagioclase in the olivine-bearing rocks is unusually sodic in corrposition, having a maximum Na₂0 content of 8.12%. A comparison of olivine and plagioclase compositions with those in other intrusions has revealed that the only other major intrusion with sodic plagioclase is the Kiglapait intrusion of Canada. In the Kiglapait intrusion the sodic plagioclase occurs in conjunction with fayalitic olivine as opposed to the forsteritic variety of this study. Chemical variations in the rocks sampled indicate that periodic replenishment of the magma from which the rocks crystallised must have occurred. In some of the olivine-bearing intervals where little fractionation is evident, replenishment seems to have been continuous. In other intervals fractionation appears to have continued uninterrupted for significant periods, prior to rejuvenation by fresh influxes of magma.

M.Sc. (Geology) / Please refer to full text to view abstract

In this experiment, the influence of phosphorus supplementation on growth and reproductive characteristics of beef cows in the semi-arid bushveld of South Africa was studied. The parameters in this study included weight, intercalving period and conception rates of cows, as well as birth weight, weaning weight and weight gain of calves. The experiment consisted of three trials. Trial 1 involved Bonsmara cows with four dietary supplementation groups. These were control, phosphorus supplementation all year round, phosphorus supplementation in the summer months and summer phosphorus supplementation with a winter lick. Trial 2 dealt with Bonsmara cows and included two dietary supplementation groups, namely control and phosphorus supplementation all year round. Trial 3 compared four different breeds (Afrikaner, Simmentaler, Nguni and Bonsmara) and included two dietary supplementation groups, notably a control group and a Kimtrafos 12 P supplementation all year round. Phosphorus supplementation had no significant effect on cow weight in Trial 1 (p > 0.1), but was significant in Trial 2 (p< 0.001) with the supplemented group performing better than the control group. In Trial 3, phosphorus supplementation had a varied effect on cow weight, because it only had an effect for the months of June to November (p< 0.05). Phosphorus supplementation had no significant effect on birth weight in any of the trials. Treatment did however either show a tendency towards significance or was significant for weaning weight and weight gain in Trial 2 (p= 0.0272 and p= 0.0524 respectively) and Trial 3 (p= 0.0587 and p= 0.0464 respectivey), with the treated groups performing better than the control groups. There was no improvement in calving interval or conception rate for phosphorus supplemented cows in any of the trials. / Dissertation (MSc(Agric))--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted