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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Descrição osteológica de um exemplar de Endothiodon (Synapsida, Dicynodontia) proveniente da Serra do Cadeado (Formação Rio Do Rasto, Permiano Superior) e suas implicações bioestratigráficas e paleobiogeográficas

Boos, Alessandra Daniele da Silva January 2012 (has links)
A presente dissertação de mestrado apresenta uma descrição detalhada do primeiro dicinodonte reportado para o Permiano da América do Sul. O material (PV 0226) é composto por um crânio parcial e mandíbulas associadas, proveniente da Serra do Cadeado, estado do Paraná, Formação Rio do Rasto. O espécime foi descrito preliminarmente na década de 70 e atribuído ao gênero Endothiodon. Tal classificação implicava em uma correlação direta com algumas das consagradas biozonas do Grupo Beaufort da África do Sul, já que este táxon é encontrado nesse depósito. Assim, o principal objetivo deste trabalho era verificar a identidade taxonômica do material brasileiro, e a partir da confirmação ou da proposição de outra identificação para o espécime, discutir brevemente as implicações bioestratigráficas e paleobiogeográficas da presença deste fóssil no Brasil. O exemplar em questão foi comparado com espécimes de Endothiodon da coleção do American Museum of Natural History, e uma extensa revisão bibliográfica foi realizada para obter informações sobre espécimes depositados em outras instituições. Por fim, o material brasileiro foi confirmado como pertencendo ao táxon Endothiodon, devido à presença de: forame pineal situado em uma bossa, protuberâncias em forma de bulbo localizadas na face antero-lateral dos dentários, bossa situada na margem ventral do jugal, grande número de dentes inseridos na superfície dorso-medial do dentário, sulco do dentário lateral à fileira de dentes na mandíbula, porção mais anterior da mandíbula em forma de um bico curvo e pontiagudo, entre outras características. Entretanto, não foi possível atribuir a este exemplar uma das quatro espécies do gênero, visto que a atual separação das espécies é dada basicamente por diferenças no comprimento do crânio. Esta feição pode refletir meramente o estágio ontogenético dos indivíduos e não diferenças em nível específico, exceto para E. mahalanobisi que aparenta ser uma forma de pequeno porte. Na realidade, outras características (região interorbital larga, presença de sínfise do dentário grácil ou robusta) apontadas como diagnósticas para o táxon são problemáticas e deveriam ser evitadas ou substituídas por outras mais informativas. Além disso, a forma de Endothiodon do Brasil apresenta uma estrutura denominada “dentary table”, recentemente identificada neste gênero. Em relação à bioestratigrafia, as correlações propostas para as faunas de tetrápodes da Formação Rio do Rasto ressaltam a semelhança dessas com associações faunísticas do Meso e Neopermiano da África do Sul e do Leste Europeu. Porém, até o momento, essas correlações são tentativas, pois poucos elementos dessas faunas são conhecidos para o Brasil e sobre estes, faltam informações relativas aos níveis estratigráficos em que foram coletados. Este último fator gera incertezas em relação à contemporaneidade dos fósseis encontrados em uma mesma localidade. Sobre a aparente escassez de vertebrados para esta formação, quando comparada a outros depósitos de mesma idade, esta parece advinda de um artifício de coleta, ou seja, o material conhecido até o momento não reflete a diversidade que essas localidades devem abrigar. O estudo detalhado de PV 0226 resultou em um artigo submetido para publicação em um periódico de cunho paleontológico. / The present master´s thesis presents a detailed description of the first dicynodont reported for the Permian of South America. The material (PV 0226) comprises a partial skull and associated lower jaws, collected in the Serra do Cadeado locality, Paraná state, Rio do Rasto Formation. The specimen was described preliminary during the 1970´s and assigned to the genus Endothiodon. This identification implied a direct correlation with some of the well-established biozones of the Beaufort Group, South Africa, since this taxon is found in this deposit. Thus, the main objective of this work was to verify the taxonomic identity of the Brazilian material and based on the confirmation or proposition of another classification for the specimen, to discuss briefly the biostratigraphic and palaeobiogeogrpahic implications of the presence of this fossil in Brazil. The specimen studied herein was compared with Endothiodon material housed in the collections of the American Museum of Natural History, and an extensive review of the literature was carried out in order to collect information about specimens housed in other institutions. Finally, it was confirmed the material from Brazil belongs to Endothiodon, due to the presence of: pineal foramen situated on a boss, prominent bulbous swellings on the anterolateral sides of the dentary, boss situated on the ventral margin of the jugal, extensive number of teeth on the mid-dorsal surface of the dentary, dentary sulcus lateral to the lower teeth row, anterior portion of the lower jaw prolonged into upwardly curved and pointed beak, among other characteristics. However, it was not possible to assign the material to one of the four species of the genus, as the current distinction of them is based mainly on differences in the skull lenghth. This feature may reflect merely the ontogenetic stage of the specimens and not differences at species level (except from E. mahalanobisi, which seems to be a small form). In fact, other characters (wide interorbital region, slender or robust dentary symphysis) pointed as diagnostic for this taxon are problematic and should be avoided or substituted for others more informative. Besides, the Brazilian form of Endothiodon bears a dentary table, recently indentified in this genus. Regarding biostratigraphy, the correlations proposed for the tetrapod faunas of the Rio do Rasto Formation highlight the similarities between these associations and others from the Mid and Late Permian of South Africa and Eastern Europe. But, until now, these correlations are tentative because few elements of these faunas were recovered from Brazil and most of them lack data about the stratigraphic levels from where they were collected. The latter leads to uncertainty concerning the age of the fossils found in the same locality. About the apparent poverty of vertebrates for this formation when compared to other deposits of the same age, it seems to be a collecting artifact, i.e. the amount of material recovered from this formation until the present does not reflect the potential diversity of it. The detailed study of PV 0226 resulted in an article submitted to a palaeontological journal.
112

Lithostratigraphy, depositional environments and sedimentology of the Permian Vryheid Formation (Karoo Supergroup), Arnot North, Witbank Coalfield, South Africa

Uys, Joanne 30 April 2009 (has links)
M.Sc. / This work documents the lithostratigraphy and interpreted depositional environments of the Permian Vryheid Formation in the most northern proximal setting yet studied in the Witbank Coalfield. Data from 924 boreholes from two mining companies (Anglo Operations Ltd. and Xstrata Coal Ltd.) drilled over 50 years, covering an area of 910km2 revealed a 35m sequence of terrigenous clastic sedimentary rocks containing two coal seams. These seams are numbered No. 1 at the base and No. 2 at the top. Delineation of facies type, facies assemblages, lateral facies distributions and computer-based three-dimensional modeling facilitated the interpretation of the palaeodepositional environments. Eleven lithofacies are defined and interpreted hydrodynamically. Facies classification is based primarily on grain size and sedimentary structures. The modeling of the borehole information uses the finite element method to interpolate the thickness, roof and floor surfaces and trend of each seam and inter-seam parting between boreholes. The spatial position of the boreholes is defined using a digital terrain model that represents the current surface topography. Lateral distributions were correlated by repositioning the boreholes using the base of the No. 2 seam as a datum. Glaciofluvial, glaciolacustrine, bed-load (braided) fluvial and constructive progradational deltaic environments are interpreted in the study area. Fluvial channel sequences are dominant and cause the thinning of the coal seams below channel axes as well as splitting of both the No. 1 and No. 2 seams. Glaciofluvial influences also affect the lower portion of the No. 1 seam. Basement palaeotopography restricts the distribution of the lower splits of the No. 1 seam. The coals either ‘pinch-out’ or are absent above basement highs but blanket the adjacent low-lying areas. In contrast to the greater Witbank Coalfield, but concurrent with other studies in the more northern proximal regions, fluvial systems dominate over deltaic systems in the study area. Glaciodeltaic, fluviodeltaic and anastomosed channel fluvial systems recognized in the remainder of the Karoo Basin were fed by the braided fluvial systems in the study area. The close proximity of the study area to the northern edge of the basin accounts for the subtle differences in lithostratigraphy and interpreted depositional environments when compared with more distal sites to the south. For example, glaciofluvial clastic sediment input in the lower portions of the No. 1 seam and post-Karoo erosion that has removed the overlying seams; the deltaic progradational sequence, above the No. 2 seam, occurs twice in succession and the bioturbation, that has become characteristic of sedimentary sequence of the Vryheid Formation above the No. 2 seam in the central and southern parts of the Karoo Basin, is not as identifiable. These differences are explained by the extreme proximal location of the study area on the northern basin margin relative to the remainder of the Karoo Basin.
113

Nitrogen and carbon costs of growth and antioxidant production during acclimation to environmental stress in two species of gethyllis

Daniëls, Christiaan Winston January 2012 (has links)
Philosophiae Doctor - PhD / Gethyllis multifolia L. Bolus and G. villosa Thunb. are winter-growing, summerblooming,deciduous and bulbous geophytes that grow naturally in the semi-arid succulent Karoo biome of South Africa. Both species grow under full sun conditions and have four distinctive growth phases: a winter (cold and wet) growing phase, leaf senescence phase towards spring, flowering phase during the hot and dry summer months, and fruit and leaf formation phase in autumn. The medicinal uses of this genus (including G. multifolia “Kukumakranka” and G.villosa “hairy kukumakranka”) range from cures for colic, digestive disturbances,teething problems, fatigue, boils, bruises and insect bites, to being used as an aphrodisiac. Gethyllis multifolia is threatened in its natural habitat and is listed in the ‘Vulnerable’ category of the ‘Red Data List of Southern African Plants’ and the ‘IUCN-World Conservation Union List of Plants’. The literature indicate that the habitats of both species are being exposed to drier conditions and is further threatened by the encroachment of invasive indigenous plant species. It is not known to which extent these factors may pose a threat to the existence of both species. The first objective of this investigation was to determine the costs of vegetative and reproductive growth during the seasonal life cycle of the plant, using carbon(C) and nitrogen (N) as a physiological currency. The second objective was to elucidate a functional basis to explain the difference in the conservation status of both species in their natural habitat. Both species were subjected to drought and shading as environmental stresses and the plant physiological performance was investigated via photosynthetic gas exchange. The third objective of the study was to evaluate the antioxidant content (total polyphenol, flavonol/flavone and flavanone content) and antioxidant capacity [ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC) and 2,2'-azino-di-3-ethylbenzthiazoline sulphonate (ABTS) radical cation scavenging ability] of natural populations and plant samples that were exposed to photo-and-drought environmental stresses. This study was done to elucidate the antioxidant profile of plant parts of natural populations as well as providing farmers, traditional healers and pharmaceutical companies with cultivation environmental conditions to enhance the antioxidant properties of the species. This investigation also attempted to isolate and characterize, by means of thin-layer chromatography (TLC) and column chromatography (CC), natural compounds from both species to lend support to the purported antioxidant benefit of both species and to further lend support to claims made by traditional healers of the medicinal potential of the genus. This study, however, did not engage in any in vivo studies or human trials to support published literature of the medicinal benefits of the genus.
114

The influence of the composition of mixed Karoo vegetation on the grazing habits of Merino and Dorper wethers

Roux, Francis Augustus January 1994 (has links)
The primary objective of this research project was to determine whether area-selective grazing, by Dorper and Merino wethers, took place in small grazing camps as governed by differences in vegetal cover. The main research techniques employed were the descending-point method for the determination of botanical composition, sub-division of the camps into gridblocks to trace sheep movement in relation to vegetation patterning, fistulated animals to determine diet selection, the electronic theodolite for micro-topography, and few minor techniques. The result have shown that area- patch- and species selective grazing are prevalent in small grazing camps under "normal" stocking densities, and that different breeds of stock (Merino and Dorper sheep) have different grazing patterns and diet selection . Climax and sub-climax areas were those primarily select ed for grazing. There is little or no correlation between botanical composition and diet selected as per fistula ted animal. The average distances travelled by Dorpers and Merinos was 2 km / day and 3.1 km/day respectively. Plant phenology did not have a detectable influence in the choice of diet.
115

Geological controls on no. 4 seam roof conditions at New Denmark Colliery, Highveld Coal Field, Karoo Basin, South Africa

Stanimirovic, Jasmina 28 January 2009 (has links)
M.Sc. / The coal-bearing Permian Vryheid Formation of the Ecca Group (Karoo Supergroup) was investigated at New Denmark Colliery, situated in the north east section of the Karoo Basin, South Africa. The lithostratigraphy of the sequence is defined in terms of conventional lithostratigraphic terminology but also by applying detailed genetic stratigraphic schemes that have previously been proposed for the adjacent coalfields. The succession is divided up into depositional sequences named after the underlying and overlying coal seams, the No. 2, 3, 4 and 5 seam sequences. The sedimentary succession was divided up into five facies, namely: conglomerate facies, sandstone facies, interlaminated sandstone-siltstone facies, siltstone facies and coal facies. These were interpreted hydrodynamically. Facies assemblages were then interpreted palaeoenvironmentally. Glacial, fluvial, deltaic and transgressive marine sequences were responsible for forming this sedimentary succession. Attention was then focussed on the main economic No. 4 seam, which is mined underground at the colliery. Detailed subsurface geological cross-sections, core sequences and isopach maps of the No. 4 seam coal and the lithologies above, were used to determine specific aspects of the depositional environment that could contribute to unstable roof conditions above No. 4 seam. Coarsening-upward deltaic cycles, fining-upward bedload fluvial cycles, glauconite sandstone marine transgressions and crevasse-splay deposits are recognized in the overlying strata. Poor roof conditions occur parallel to palaeochannel margins because the interbedded channel sandstone and adjacent flood plain argillites cause collapsing along bedding plane surfaces. Rider coals overlying thin crevasse-splay sequences in close proximity to the No. 4 seam, create one of the most serious roof conditions; complete collapse occurs along the rider coal contact with the underlying splay deposits. Differential compaction of mudrock/shale/siltstone over more competent sandstone causes slickensided surfaces that weaken the roof lithologies. Correct identification of these sedimentological features will enable the prediction of potential poor roof conditions during mining operations and mine planning.
116

Laser ablation ICP-MS age determination of detrital zircon populations in the Phanerozoic Cape and Lower Karoo Supergroups (South Africa) and correlatives in Argentina.

Vorster, Clarisa 14 January 2014 (has links)
Ph.D. (Geology) / The successions of the Cape- and Karoo Supergroups preserve an integrated history of sedimentation along the paleo-Pacific margin of Gondwana from the Paleozoic to the Early Mesozoic. The Cape- and Karoo Supergroups have been well studied with regard to stratigraphy, sedimentary facies and depositional environment. However, the nature and location of their source regions, especially for the changeover from deposition within an Atlantic-type continental margin basin for the successions of the Cape Supergroup to an Andean-type continental foreland basin for some of the units of the Karoo Supergroup, remains poorly understood. In order to shed light on the nature of these source regions, a comprehensive U-Pb detrital zircon study of the successions of the Cape- and lower Karoo Supergroups was launched. A representative number of samples from the upper and lower successions of the Table Mountain- Bokkeveld- and Witteberg Groups of the Cape Supergroup as well as the Dwyka and Ecca Groups of the Karoo Supergroup were collected throughout the western, southwestern and southern Cape region. A few samples of the Dwyka Group were also collected within the more eastern outcrop regions of the succession located in Kwazulu-Natal. The sedimentary rocks of the Natal Group and Msikaba Formation have long been regarded as coeval with the Cape Supergroup. Similar to the successions of the Cape- and Karoo Supergroups, very little is known about their sedimentary source regions. Also, their relative age of sedimentation remains poorly constrained. The U-Pb detrital zircon study of the successions of the Cape- and lower Karoo Supergroups was thus extended so as to include the successions of the Natal Group and Msikaba Formation. The detrital zircon age populations of the successions of the Natal Group and Msikaba Formation would not only improve the present understanding with regards to the sedimentary source regions to these units but would also facilitate the evaluation of possible correlations between these units and the stratigraphic units of the Cape Supergroup. Samples of both the lower Durban Formation and the upper Mariannhill Formation of the Natal Group and the Msikaba Formation (which is presently regarded as being part of the Cape Supergroup) were therefore collected within their respective outcrop regions in the Kwazulu-Natal area. The similarities in litho- and bio-stratigraphy between the successions of the Cape- and Karoo Supergroups and those of the Ordovician to Early Permian successions of the Ventania System and the Ordovician to Silurian successions of the Tandilia System in Argentina have long been recognized. Although the detrital zircon populations of some of the formations within these Systems have been evaluated in the past, it is yet to be determined whether these successions and those of the Cape- and lower Karoo Supergroups have certain source regions in common. In order to facilitate such a comparison, samples of selected units of the Ventania System were therefore collected near Sierra de la Ventania, while a sample of the Balcarce Formation of the Tandilia System was obtained near Mar del Plata. The detrital zircon age populations of the successions of the Ventania and Tandilia Systems were also further evaluated in the light of establishing or confirming a time-correlation between these formations and those of the Cape- and lower Karoo Supergroups. U-Pb age determination of the detrital zircons population of the samples was conducted by means of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). Although LA-ICP-MS is a routine, well-established technique where the U-Pb age determination of detrital zircons is concerned, it was yet to be established at the centralized analytical facility of the University of Johannesburg, SPECTRUM, using the instrumentation currently available (i.e. 213nm Nd:YAG laser coupled to Quadrupole-based ICP-MS). The U-Pb age determination of detrital zircons was therefore preceded by a fair amount of instrument optimization and method development. Well studied shortcomings of U-Pb detrital zircon dating by LA-ICP-MS such as laser induced elemental fractionation, mass discrimination effects and as well as the possible occurrence of minor common-Pb needs were addressed and corrected for. The detrital zircon populations of successions in the Cape Supergroup have a distinct major Neoproterozoic to Early Cambrian age component, which can be attributed to an input of detritus from successions related to the Pan-African Orogeny in South Africa, such as the Gariep- and Saldania Belts located towards the north of the Cape Basin. A substantial amount of Mesoproterozoic detrital zircon grains is also present in all the samples from the successions of the Cape Supergroup. These grains of Mesoproterozoic age were probably derived from the Namaqua-Natal Metamorphic Province, which is also regarded as the source of some minor amounts of Paleoproterozoic detrital zircon grains. The near absence of Archean grains from the detrital zircon populations of the successions of the Cape Supergroup is notable, and is thought to be due to the Namaqua-Natal Metamorphic Province acting as a geomorphological barrier at the time of their deposition. The minor Paleozoic (Ordovician to Carboniferous) detrital zircon populations in the samples from the formations of the Cape Supergroup increase progressively upwards through the succession. ....
117

Implications of the geological structure of the Qoqodala dolerite ring complex for groundwater dynamics

Nhleko, Olivia Lebogang January 2008 (has links)
Magister Scientiae - MSc / The chief aim of this project is to investigate the groundwater flow dynamics of the various fractured-rock aquifers (deep and shallow) associated with Karoo dolerite ring complexes in the Qoqodala area (northeast of Queenstown in the Eastern Cape Province). / South Africa
118

Applying experimental economics to determine consumers' willingness to pay for food attributes

Van Zyl, Karlien 07 December 2011 (has links)
Changes in the features of food demand and consumption have moved from the mass consumption model towards an increasing qualitative differentiation of products and demand. This movement towards addressing consumers’ demand for food products with more advanced quality attributes has led to increasingly complex food qualification processes and a proliferation of standards. Accompanying these changes in the agro-food system is a growing consumer concern for food safety and quality. Even though these trends are also permeating South Africa, little research has been done on the local quality dynamics of this emerging country. There is therefore the need to investigate consumers’ food choice behaviour in a developing country context, such as South Africa. Consumers’ quality perception and decision making process regarding food products is quantified through measuring consumers’ willingness to pay (WTP)for a given attribute in a food product. Willingness to pay refers to the maximum monetary amount that a consumer is willing to pay for a specific product representing a bundle of product attributes. The general objective of this study is to test the application of experimental auctions as one of the available methods to measure consumers’ willingness to pay, in order to determine the applicability of experimental auctions to specific research scenarios – for example the case of food products with advanced quality attributes in a developing country context. Sample selection for the experiment was done through a combination of random and convenience sampling. The total sample amounted to 31 participants. The target population was high income, established South African consumers, who are regular consumers of red meat and also the main buyers of groceries in the household. A pre-auction survey was done to determine the exact demographic composition of the sample as well as gaining insight into the sample’s buying behaviour and attitudes towards red meat, specifically Karoo lamb. A random nth price auction was conducted to obtain willingness to pay estimates for a premium on certified Karoo lamb. Various demographic and behavioural variables were linked to participants’ individual bids in order to determine the possible influence of these variables on participants’ bidding behaviour. This research study tested the application of an experimental auction mechanism in the food marketing context of a developing country. To the knowledge of the researcher, it is the first study of its kind done in South Africa. It was worthwhile to investigate this method as an alternative to stated preference methods in the field of food choice behaviour, because the auction conducted during this research project succeeded in giving meaningful insights into the possibilities of the certification of meat of origin in a developing country like South Africa. From the auction results, a general positive willingness to pay for certified Karoo lamb was observed, with an average premium recorded of R10.90/500g of loin chops. The impact of additional information was clearly visible as bids increased substantially after information treatments about the product were introduced. It was found that female respondents and respondents from the older age group generally bid higher premiums for Karoo lamb. Respondents buying red meat and sheep meat (i.e. referring to mutton and lamb products) from Woolworths and Spar also indicated a higher positive willingness to pay a premium for certified Karoo lamb. With specific reference to the case study product, a positive willingness to pay for certified Karoo lamb was determined in this study. The concerns raised by participants about the lack of availability and authenticity of Karoo lamb, serves as an indication of the need for a formal certification process of food products in South Africa. / Dissertation (MCom)--University of Pretoria, 2011. / Agricultural Economics, Extension and Rural Development / unrestricted
119

Asymmetric information, principal-agent behaviour and governance mechanisms in the South African lamb supply chain

Van der Merwe, Melissa January 2017 (has links)
The recent addition of Karoo Lamb to South Africa’s repertoire of products with a regional identity attracted extensive publicity. The news headlines that spoke of challenges to protect the geographical name, discrepancies among supply chain stakeholders and the outright opportunism and exploitation of the geographical name made Karoo Lamb a particularly interesting case study to examine. Regrettably, the niche product “Karoo Lamb” has not yet come to its own. In an effort to support the development of this initiative, the thesis sets out to address the central question; “How do we increase farmer participation in differentiated product supply chains, whilst discouraging opportunistic behaviour so that the performance of these chains can be optimised?” The overarching question, mentioned above, is addressed in four independent but related research papers by using the differentiated Karoo Lamb supply chain as a case study. The specific questions considered in these papers are:  What are the claims most vulnerable to opportunistic behaviour?  What drives a farmer’s tendency to behave opportunistically, and how can these drivers be used to prevent opportunistic behaviour?  What factors encourage a farmer to participate in a differentiated supply chain?  What enforcement mechanisms are best suited to prevent the opportunistic behaviour of farmers?  What governance mechanisms are currently employed to govern the supply chain?  Are the governance and enforcement mechanisms properly aligned to guarantee the authenticity of the differentiated product? The thesis employed the principals of agency theory, transaction cost economics, and contract theory to address the practical problems faced by the Karoo Meat of Origin certification scheme. The thesis combined quantitative and qualitative research methods to analyse the data collected from four primary stakeholders involved in the Karoo Lamb supply chain. From the total population of 209 certified Karoo Lamb farmers, 73 farmers were interviewed on their farms in the Karoo region. In addition to the farmers, five abattoirs, two processors and/or packers and five retail outlets were interviewed. Results supported the expectation that a farmer’s decision to invest in the collective reputational capital of a product is shaped by his/her relationship with the abattoir, and the ease with which business is conducted. The easier it is for the farmer to do business with the abattoir the more likely the farmer is to invest in the Karoo Lamb initiative. Other, more personal attributes, such as the farmer’s risk profile, education and his/her network also proved to influence his/her willingness to invest in the collective reputation. The efforts to increase the membership base of Karoo Lamb contributes to the success story of Karoo Lamb. The success of the initiative, however, remains threatened by opportunism. The investigation revealed the “from the Karoo” and “free range” claims as the most vulnerable to opportunistic behaviour specifically during times of droughts. The study further revealed a lack of information exchange between the farmers and abattoirs, specifically regarding droughts, feeding practices and disease treatments, as the leading driver for opportunistic behaviour. An increase in information sharing, within the farmer network, and with the abattoir, is therefore recommended. This is the main strategy to reduce or eradicate the opportunistic behaviour of farmers. In addition to broadening farmer investments in the reputational capital of Karoo Lamb and to preventing the opportunistic behaviour of farmers, the success of the Karoo Lamb initiative also requires an alignment between the enforcement and governance mechanisms. The investigation supported the notion that the State-appointed third party is relatively unsuccessful when it specifically comes to the monitoring of the Karoo farmers for compliance with production standards. Due to the failure of the third party, the thesis made an attempt to explore alternative monitoring and enforcement mechanisms. The results indicate that the majority of the Karoo Lamb stakeholders preferred monitoring and enforcement mechanisms that include more frequent monitoring and stricter prosecution strategies to deal with non-compliant stakeholders. Owing to many years of commodity style operations throughout the supply chain, the correct vehicle for ensuring the proper implementation of the enforcement mechanisms remains a challenge. The assessment of the Karoo Lamb supply chain reveals non-contractual arrangements with qualified partners as being the most frequently utilised governance mechanism. However, this mechanism is not sufficient when the third party fails to monitor and enforce the production standards accurately. Therefore, with a view to ensuring the credibility of Karoo Lamb, a move to toward more hierarchical arrangements, are expected, which would provide a stronger focus on private or mutual enforcement mechanisms. This means that the stakeholders in the supply chain would be jointly responsible for the credibility of the product and therefore jointly responsible for the enforcement of quality and origin standards. / Thesis (PhD)--University of Pretoria, 2017. / Red Meat Research and Development SA / Bill and Melinda Gates Foundation / Agricultural Economics, Extension and Rural Development / PhD / Unrestricted
120

Hydrocarbon potential of the Prince Albert Formation, Ecca Group in the main Karoo Basin, South Africa.

Mosavel, Haajierah January 2020 (has links)
Philosophiae Doctor - PhD / This thesis focusses on the hydrocarbon potential of the Prince Albert Formation in terms of its shale gas potential. Unconventional gas production from hydrocarbon-rich shale formations, known as “shale gas”, is one of the most rapidly expanding trends in onshore oil and gas exploration and exploitation today. In South Africa, the southern portion of the main Karoo Basin is potentially favourable for shale gas accumulation and may become a game changer in the energy production regime of the country. The Prince Albert Formation was selected for research, since previous studies in South Africa have focused on shale from the Whitehill Formation, which together with the underlying Prince Albert Formation, occur within the lower Ecca Group in the main Karoo Basin. The petrophysical properties and shale gas potential of the Prince Albert Formation was determined using the parameters of mercury porosimetry, total organic carbon (TOC), vitrinite reflectance, Rock-Eval and residual gas measurements. The lithostratigraphy, rock classification, and depositional environment of the Prince Albert Formation, together with the adjacent parts of the overlying Whitehill Formation and underlying Dwyka Group within the southern part of the main Karoo Basin were addressed. Rock types were characterised using X-ray fluorescence (XRF), X-Ray diffraction (XRD) and statistical analysis. Geochemical proxies and stable isotopes (δ18O, δ13C and δ15N) were used to identify the depositional environment. Additionally, the Dwyka Group, Prince Albert and Whitehill formations were correlated with equivalent Southern Gondwanaland units to understand basin development. The results of the shale gas study of the Prince Albert Formation showed porosities ranging between 0.08 and 5.6%, permeabilities between 0 and 2.79 micro-Darcy, TOC between 0.2 and 4.9 weight % and vitrinite reflectance values between 3.8 to 4.9%. Rock-Eval analysis indicated that the kerogen in the shale was Type III and IV and hydrogen indices were less than 65 mg/g. Free or absorbed gas was not detected in the recently drilled boreholes KZF-01 and KWV-01 used in this study. It is probable that the absence of gas is a result of overmaturity due to tectonic duplication in KZF-01 and thermal degassing associated with dolerite intrusions in KWV-01. Although the porosity and TOC values of the Prince Albert Formation shales across the southern part of the main Karoo Basin are comparable with, but at the lower limits of, those of the gas-producing Marcellus shale in the United States (porosities between 1 and 6% and TOC between 1 and 10 weight %), the high vitrinite reflectance values indicate that the shales are overmature with questionable potential for generating dry gas. A comprehensive rock classification were compiled for the Prince Albert Formation, which consists of shale and minor ferruginous shale ranging between thicknesses of 30 and 168 m based on field work and core descriptions. Mineralogical, geochemical and statistical data, classified collected samples as Fe-shale, phosphatic shale, manganiferous shales, shale, wacke, Fe-sand and litharenite. In unconventional resources, understanding the depositional environment is important in delineating the depositional process and bottom water conditions. The Prince Albert Formation was interpreted as marine forming under dysoxic to euxinic conditions. δ 13C values range between -17.5 and -23.1 ‰ and δ 15N between 8.5 and 11.1 ‰ reflecting marine conditions. Sediments of the Prince Albert Formation were interpreted as middle to outer continental shelf deposits based on various lithologies identified and XRF data (geochemical proxies). Compiled literature of the karoo- type basins in Southern Gondwanaland provides a correlation of the Dwyka Group, Prince Albert and Whitehill formations in South Africa. Based on stratigraphy and radiometric dating, the Dwyka Group, Prince Albert and Whitehill formations have been correlated with lithostratigraphic units in the Falkland Islands, Namibia (Huab, Karasburg and Aranos basins), the Ellsworth Basin of Antarctica and the Sauce Grande and Parana basins of South America. This correlation suggest that the main Karoo foreland system was subjected to very similar tectonic influences present in the other karoo-type basins of Southern Gondwanaland. In conclusion, results from this research indicate that viable conditions for shale gas might exist within the “sweet spot” areas constrained by formation thickness being > 30 m, relative dolerite intrusion of < 20%, relative total organic carbon content > 4 weight %, and maturity of < 3.5%. It is essential that new exploration boreholes be drilled within the “sweet spot” areas to test whether the lower Ecca Group (Prince Albert and Whitehill formations) has the potential to generate viable shale gas.

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