Sedimentary, geochemical and geophysical study of the Ecca group, Karoo supergroup and its hydrocarbon potential in the Eastern Cape Province, South Africa
- Authors: Baiyegunhi, Christopher
- Date: 2017
- Subjects: Sediments (Geology) -- South Africa -- Eastern Cape Sedimentology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/4881 , vital:28658
- Description: The Ecca Group of Karoo Supergroup is a sedimentary rock sequence that deposited between the Late Carboniferous (Dwyka Group) and the Late Permian-Middle Triassic (Beaufort Group). The Ecca Group investigated in this study is situated in the Eastern Cape Province of South Africa and it comprises mainly of shales, mudstones, siltstones and sandstones. The Ecca Group sequence contains considerable carbon content and suitable thickness to make it an ideal target for shale gas exploration. Previous studies put more emphasis on the geology and stratigraphy of the Ecca Group, this study revised the stratigraphy, and put new insight on the petrography, depositional processes, sedimentary facies, provenance, paleoweathering, tectonic setting, subsidence rates and history, electrical resistivity, source rock characteristics and diagenesis of the potentially feasible sandstone and mudrock reservoir rocks of the Ecca Group. Based on the lithological features, sedimentary structures and facies characteristics, the stratigraphy of the Prince Albert, Whitehill, Collingham and Fort Brown Formations of the Ecca Group is now subdivided into two informal members each, i.e. Lower Member and Upper Member. Furthermore, the Ripon Formation is now subdivided into three informal members. Each member has been asigned a lithological name. The grain size parameters show that most of the Ecca Group sandstones are very fine to fine grained, poorly to moderately well sorted, mostly near-symmetrical and mesokurtic in grain-size distribution. The linear discriminant function analysis is dominantly indicative of turbidity current deposits under deep marine environment for Prince Albert, Whitehill and Collingham Formations, shallow marine environment for Ripon Formation, while the Fort Brown Formation is lacustrine-deltaic deposits. Modal composition analysis and petrography studies revealed that the detrital components of the sandstones are dominated by monocrystalline quartz, feldspar and lithic fragments. The sandstones are compositionally and texturally immature and can be classified as feldspathic wacke and lithic wacke. The provenance analysis revealed plutonic and metamorphic terrains as the main source rocks with minor debris derived from recycled sedimentary rocks. The detrital modal compositions of these sandstones are related to back arc to island and continental margin of tectonic setting. Based on the detailed sedimentological analyses of outcrop and borehole data, fourteen lithofacies were identified and seven facies associations (FAs) were recognised. The facies associations are: FA 1: Shale and mudstones intercalated with siltstones, FA 2: Carbonaceous shale, mudstone with subordinate chert and sandstone, FA 3: Mudstones rhythmite with thin bedded mudstone and lenticular siltstone, FA 4: Greyish medium bedded sandstone intercalated with laminated mudstone, FA 5: Dark-grey medium to thick bedded mudstone and siltstone, FA 6: Thin to medium bedded sandstone alternated with thin bedded carbonaceous mudstone, and FA 7: Varved mudstone rhythmite intercalated with siltstone and minor sandstone. Sedimentological characteristics of the identified facies associations indicate four deposition environments, namely, deep marine basin, turbidite, shallow marine and lacustrine environments, which constitute a gradually regression sequence as a result of sea-level dropping and shallowing of the basin during the developmental processes. Geochemical analysis of the Ecca mudrocks and sandstones revealed that the rocks are of quartzose sedimentary provenance, suggesting that they were derived from a cratonic interior or recycled orogen. The petrography and geochemistry of the sandstones indicated that the source areas are composed of plutonic and metamorphic rocks with a minor component from sedimentary rocks. The geochemical diagrams and indices of weathering suggested that the granitic source rocks underwent moderate to high degree of chemical weathering. The tectonic setting discrimination diagrams support passive continental margin setting of the provenance.
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- Date Issued: 2017
Investigating the English vocabulary needs, exposure, and knowledge of isiXhosa speaking learners for transition from learning to read in the Foundation Phase to reading to learn in the Intermediate Phase : a case study
- Authors: Sibanda, Jabulani
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1968 , http://hdl.handle.net/10962/d1011790
- Description: The nature of learners' transition from Grade 3 to Grade 4 has serious and far reaching ramifications for their educational success in the subsequent grades. This is true of the South African education system, as it is for several other education contexts. The challenge that complicates the transition is largely a lexical one. It is with that understanding that the present study aimed to do three things namely: to determine the vocabulary needs of Grade 3 learners for transitioning to Grade 4; to establish the extent to which Grade 3 isiXhosa speaking learners are exposed to, and prepared for, the acquisition of that requisite vocabulary; and to establish the extent of Grade 4 learners' knowledge of that vocabulary at the beginning of the year. The vocabulary needs of Grade 3 learners for the transition to Grade 4 were determined from the Grade 4 subject textbook corpus. Word frequency was the criterion used to determine the usefulness and critical importance of a word for the transition. The AntConc concordance software program was used to generate word frequencies. Words with high frequency across the different subject areas, which were confirmed as high frequent in four other known word lists, were considered as constituting the vocabulary needs of learners at the verge of this significant transition. The extent of learners' preparedness for transitioning to Grade 4 in terms of their vocabulary exposure and vocabulary instruction was determined through teacher interviews, classroom observations, analysis of teacher classroom talk, analysis of the exposure and recycling of high frequent vocabulary in Grade 3 reading materials and classroom print. From these diverse sources, findings point to a paucity in both the exposure and recycling of the requisite vocabulary in these sources of classroom language input. Classroom observations and teacher interviews attest to lack of deliberate vocabulary instruction in the Grade 3 English First Additional Language lessons. The only extensive coverage of the requisite vocabulary was in the Grade 3 reading materials which included Big books, Readers and Workbooks. The Grade 4 learners' knowledge of the 60 high frequency words was tested through nine vocabulary tests, three of which tested their knowledge of word recognition, three tested passive word knowledge and the remaining three tested learners' active word knowledge. All the Grade 4 learners in the ten participating schools (297) were tested. Performance in the tests indicated that Grade 4 learners' knowledge of words requisite for reading to learn was low. That observation was consistent with an analysis of learners' performance per school, per district, per word, per test and per word bands. Tests of word recognition were done better than those of passive word knowledge and active word knowledge. Particularly problematic was test 4 which tested learners' knowledge of definition of words.
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- Date Issued: 2014
Synthesis and characterisation of novel platinum (II) complexes potential chemotherapeutic drugs
- Authors: Datt, Michael Steven
- Date: 2001
- Subjects: Chemotherapy Platinum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4366 , http://hdl.handle.net/10962/d1005031
- Description: The present study involves the preparation of novel mixed-ligand platinum(II) complexes in the hope of expanding the range of platinum(II) complexes that exhibit anticancer activity and which are less toxic and have a broader spectrum of activity than cisplatin and its analogues. To this end, N-(3-R-benzoyl)-N’,N’-diethylthiourea, N-(3-R-benzoyl)-N’-morpholinothiourea, N-(3-Rbenzoyl)-N’,N’-di(2-hydroxyethyl)thiourea (R = NO2, Cl, H, CH3, OCH3), N,N-diethyl-N’-menthyloxycarbonylthiourea and N-menthyloxycarbonyl-N’-morpholinothiourea ligands, and their corresponding mixed-ligand platinum(II) complexes of the type [PtCl(L)(RR’SO)], were synthesised and characterised by elemental analyses, IR, 1H and 195Pt NMR spectroscopy and, in some cases, X-ray crystallography. Dimethylsulfoxide complexes were prepared using all the ligands, while complexes containing unsymmetrically substituted sulfoxides were prepared using the N-benzoyl-N’,N’-diethylthiourea and ,N-diethyl-’-(-)-(3R)-menthyloxycarbonylthiourea ligands only. The molecular structures of cis-(S,S)-[PtCl(DMSO)(L)] (where L = N-benzoyl-N’,N’-diethylthioureato, N-(+)-(3S)-menthyloxycarbonyl-N’-morpholinothioureato), cis-(S,S)-[Pt(N-benzoyl-N’,N’-diethylthioureato)Cl(MPSO)] and cis-[Pt(N-benzoyl-N’,N’-diethylthioureato)2] were determined by X-ray crystallography. The X-ray crystal structure of N,N-diethyl-N’- (-)-(3R)-menthyloxycarbonylthiourea was also determined. The spectroscopic and crystallographic data are consistent with complexes containing a (S,O)-chelated ligand and a sulfur-bonded sulfoxide ligand. However, the 1H and 195Pt NMR studies showed that the alkoxycarbonylthioureato complexes exist as geometric isomers with the sulfoxide coordinated either in a cis-(S,S) or trans-(S,S) arrangement with respect to the sulfur donor atom of the chelated ligand, whereas the acylthioureato complexes yielded only cis-(S,S)-[PtCl(L)(RR’SO)] complexes. The difference in the coordination chemistry of the acylthiourea and alkoxycarbonylthiourea ligands was examined further by treatment of the [PtCl(DMSO)(L)] complexes, where L = Nbenzoyl-N’,N’-diethylthioureato, N-benzoyl-N’-morpholinothioureato, N,N-diethyl-N’-(-)-(3R)- menthyloxycarbonylthioureato and N-(+)-(3S)-menthyloxycarbonyl-N’-morpholinothioureato, with PPh3 to give the corresponding [PtCl(L)(PPh3)] and [Pt(L)(PPh3)2]+ complexes. 31P NMR studies of these complexes reveal that the alkoxycarbonylthioureato ligands bind less strongly than the acylthioureato ligands, which is consistent with the crystallographic studies. The morpholine derivatives of the acylthioureato and alkoxycarbonylthioureato ligand systems also appear to bind less tightly than the diethyl derivatives. The weaker binding properties of the alkoxycarbonylthioureato ligands might be a possible explanation for the observed geometric isomerisation of these complexes, with the mechanism of isomerisation involving a chelate ringiv opening step. Furthermore, crystallographic and 31P NMR studies suggest that the acylthioureato carbonyl oxygen donor atom is relatively softer and therefore has a greater trans-influence than the carbonyl oxygen donor atom of the alkoxycarbonylthioureato ligand. The substitution kinetics of the chloride and sulfoxide leaving groups by azide, iodide, thiocyanate, triphenylphosphine, 2-mercaptobenzimidazole, 4-(dimethylamino)pyridine and thiourea, from selected cis-(S,S)-[PtCl(N,N-dialkyl-N’-(3-R-benzoyl)thioureato)(RR’SO)] complexes, in methanol, were evaluated to determine if variation of the electronic properties of the chelated ligand and variation of the sulfoxide have a significant influence on the reactivity of these complexes. Two consecutive reactions were observed. It was found that neutral nucleophiles initially substitute the dimethylsulfoxide, while anionic nucleophiles substituted the chloride ligand. For all the nucleophiles studied, the first substitution step was evaluated, except for triphenylphosphine and 4-(dimethylamino)pyridine, where the second step was also evaluated. The overall order of reactivity for the first substitution step was; N3 - < DMAP < I- < SCN- < MBI < thiourea < PPh3, with the rate varying three orders of magnitude. The substitution of the dimethylsulfoxide ligand by PPh3 from cis-(S,S)-[Pt(N-benzoyl-N’,N’-diethylthioureato)Cl-(DMSO)] to form cis-(S,P)-[Pt(N-benzoyl-N’,N’-diethylthioureato)Cl(PPh3)] was confirmed by X-ray crystallography. In general, manipulation of the chelating moiety, as well as interchanging the sulfoxide did not alter the reactivity of these complexes to a great extent. The anticancer activity of all the platinum(II) sulfoxide complexes were evaluated against a HeLa cell line, of which three complexes, cis-(S,S)-[PtCl(DMSO)(N,N-diethyl-N’-(3-nitrobenzoyl)- thioureato)], cis-(S,S)-[PtCl(DMSO)(N-morpholino-N’-(3-nitrorobenzoyl)thioureato)] and cis-(S,S)-[PtCl(DMSO)(N-(3-methoxybenzoyl)-N’-morpholinothioureato)] exhibited a concentration dependent anti-proliferative effect, but were less potent than cisplatin. These three complexes displayed a similar dose response in a MCF-7 cell line. Preliminary morphology studies with the three biologically active complexes in a HeLa cell line suggest that they induce cell death by apoptosis. Preliminary pBR322 plasmid DNA binding studies of selected [Pt(acylthioureato)Cl(RR’SO)]complexes clearly indicate that these complexes have a different mode of binding to DNA than cisplatin.
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- Date Issued: 2001
The administration and organisation of independent study topics with special reference to secondary school geography
- Authors: van Harmelen, Ursula
- Date: 1992
- Subjects: Geography -- Study and teaching (Secondary) , Project method in teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1419 , http://hdl.handle.net/10962/d1003300
- Description: Traditional school subjects are having to compete for a place in a curriculum which is increasingly judged according to its perceived utilitarian value. According to current educational theory, geography's role in the curriculum is to develop concepts, skills, values and attitudes that allow pupils to understand the human and environmental issues which face their communities and communities throughout the world. In order to achieve these aims, teachers need to adopt a learner-centred teaching approach, yet geography teachers are faced with the dilemma of having to develop participatory teaching strategies within an existing structure which is largely product oriented. This thesis attempts to illustrate how changes can be effected in the approach to the teaching of geography, while working within existing syllabus constraints and while continuing to meet the demands made by the current examination system. To this end, Independent Study Topics are analysed as a means to bring about the desired changes in geographical education. The concept, Independent Study Topics as a 'blanket term' (Diepeveen, 1986) for pupil-centred activities is relatively recent in terms of the South African geography syllabus. In order to obtain greater clarity about the concept and its implications for geography teaching, this study examines current geographical theory relating to learner-centred approaches and relates them to teachers' perceptions of the role of IST in the geography curriculum. The second aspect of the study is concerned with the implementation of Independent Study Topics in a classroom research setting. The organisation and administration of Independent Study Topics in a single school setting is analysed and evaluated as a process of change. This analysis provides guidelines for developing a learner-centred approach which is necessary to ensure that geography retains its position in the school curriculum of the 1990's and beyond.
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- Date Issued: 1992
A study of the nature, function and availability of orders of restitutio in integrum and specific performance as remedies in South African law
- Authors: Lambiris, Michael A
- Date: 1987
- Subjects: Restitutio in integrum (Roman law) Restitutio in integrum -- South Africa Remedies (Law) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3703 , http://hdl.handle.net/10962/d1004752
- Description: This study is of two remedies that are available in South African law: orders of restitutio in integrum, and specific performance. The study demonstrates that, by treating these remedies as legal topics in their own right, a greater understanding emerges of their inherent characteristics, the role that they play in the law, and of the particular circumstances in which these remedies are available. An order of restitutio in integrum performs an important and unique function in South African law. The fundamental realisation is that it is a remedy in terms of which the courts exercise an extraordinary and discretionary power, and nullify ab initio legal transactions, or the legal consequences of events, which were previously perfectly valid and enforceable at law. Because of the extraordinary nature of this remedy, the circumstances in which it is available are limited by the requirement that iusta causa must exist to justify nullification. Further, before the remedy is available, the person seeking relief must have suffered loss or prejudice as a result of the event complained of. Finally, a mutual restoration of benefits received by the persons involved is required. The nature and effect of orders of restitutio in integrum, and the essential elements which determine the availability of the remedy, enable it to be distinguished from, and contrasted with, other remedies in South African law. An order of specific performance is available in South African law, at the option of a plaintiff, to enforce the actual performance of contractual undertakings. The remedy is appropriate to enforce positive undertakings, as well as acts of restraint. For the remedy to be available, it is firstly necessary that a contractual obligation be proved to exist. Secondly, performance of that obligation must be due. Thirdly, the performance sought must not in fact have already been rendered. These elements determine the availability of the remedy in particular factual circumstances, such as in cases involving pre-emptive rights. The nature and characteristics of the remedy are determined by principles of South African, and not English law. The remedy is available as of right in South African law, but subject to a discretionary power of a court to refuse to order specific performance. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
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- Date Issued: 1987