Primary production of Swartvlei in mid-summer 1980, with emphasis on the production ecology of the littoral zone
- Authors: Taylor, David Ian
- Date: 1981
- Subjects: Estuarine ecology -- South Africa , Estuarine ecology -- South Africa -- Swartvlei , Ecology -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5820 , http://hdl.handle.net/10962/d1007320 , Estuarine ecology -- South Africa , Estuarine ecology -- South Africa -- Swartvlei , Ecology -- Research -- South Africa
- Description: From Introduction: Energy passes through an ecosystem via a multiplicity of interconnected routes, which can be broadly categorised into trophic and detrital pathways. The "metabolic activity" of most lakes will be governed predcminantly at the base of these two routes; namely, the primary producer and decanposer levels, respectively (Wetzel and Allen, 1972). The importance of the littoral primary producers (especially the aquatic macrophytes) in the functioning of the Swartvlei ecosystem has been emphasised in a comprehensive report by Howard-Williams and Allanson (1978) dealing with the lake system fran 1975 to 1978. They noted that although the littoral shelf (<2m below low water level) occupies only 43% of the lake's surface area it contributed 64% of the total annual primary production during the period investigated. This was largely due to the dense Potamogeton pectinatus stands which alone accounted for 52% of the total carbon input into the lake by plants. The fact that the production/biomass ratio for P. pectinatus was only 1,2:1 suggested that its importance as a primary producer in Swartvlei was largely due to its high bianass. (Biomass, or standing stock, is used in this report as defined by Waters (1977); namely, "the amount present at a point in time, expressed best as quantity per spatial unit".)
- Full Text:
- Authors: Taylor, David Ian
- Date: 1981
- Subjects: Estuarine ecology -- South Africa , Estuarine ecology -- South Africa -- Swartvlei , Ecology -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5820 , http://hdl.handle.net/10962/d1007320 , Estuarine ecology -- South Africa , Estuarine ecology -- South Africa -- Swartvlei , Ecology -- Research -- South Africa
- Description: From Introduction: Energy passes through an ecosystem via a multiplicity of interconnected routes, which can be broadly categorised into trophic and detrital pathways. The "metabolic activity" of most lakes will be governed predcminantly at the base of these two routes; namely, the primary producer and decanposer levels, respectively (Wetzel and Allen, 1972). The importance of the littoral primary producers (especially the aquatic macrophytes) in the functioning of the Swartvlei ecosystem has been emphasised in a comprehensive report by Howard-Williams and Allanson (1978) dealing with the lake system fran 1975 to 1978. They noted that although the littoral shelf (<2m below low water level) occupies only 43% of the lake's surface area it contributed 64% of the total annual primary production during the period investigated. This was largely due to the dense Potamogeton pectinatus stands which alone accounted for 52% of the total carbon input into the lake by plants. The fact that the production/biomass ratio for P. pectinatus was only 1,2:1 suggested that its importance as a primary producer in Swartvlei was largely due to its high bianass. (Biomass, or standing stock, is used in this report as defined by Waters (1977); namely, "the amount present at a point in time, expressed best as quantity per spatial unit".)
- Full Text:
Review of carbonate hosted lead-zinc (copper) deposits and the geological factors affecting their shape, size and grade
- Authors: McDonald, B
- Date: 1981
- Subjects: Lead ores , Zinc ores , Copper ores , Sedimentology , Sedimentation and deposition
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5028 , http://hdl.handle.net/10962/d1006903
- Description: From Introduction: For at least two centuries and a corresponding number of generations of geologists and miners there has been active argument concerning the origin of certain types of carbonate hosted mineral deposit. The characterization of the type itself was and still is debatable. Objections have been raised to grouping several examples under one heading because each has its individually distinctive features. ·This is especially applicable to the carbonate hosted lead-zinc "sedimentary" deposits. The type that will be discussed in the text to follow is composed chiefly of galena, sphalerite, barite and fluorite, with pyrite , marcasite and chalcopyrite as conspicuous accessory ore minerals. Exceptions to this general copper deficient characteristic displayed by the sedimentary carbonate-hosted lead-zinc deposits are the deposits at Tsumeb and Kombat, Namibia. These deposits are hosted by the carbonate sequence of the Otavi Shelf sediments, and copper, in the form of tennantite, chalcopyrite and bornite, is the major ore constituent. Calcite, aragonite, dolomite and quartz are the commonest nonmetallic gangue minerals but siderite and silica may also be present. In contrast with other lead and zinc sulphide (volcanogenic) deposits, those to be considered here seldom carry noteworthy amounts of silver or any other precious metals. Commonly the country rock is a carbonate; limestone or dolomite, but deposits in. sandstone, shale and conglomerate are not unknown. Characteristic features are ore bodies that extend parallel or nearly so with the bedding although many such deposits are partly, or completely developed along crosscutting fissures and breccias. Some observers regard these fissure fillings as evidence for a magmatic source of the metals, whereas others regard them as an indication of remobilization of ions, metals or minerals orginally present in low-grade stratiform deposits elsewhere in the stratigraphic succession.
- Full Text:
- Authors: McDonald, B
- Date: 1981
- Subjects: Lead ores , Zinc ores , Copper ores , Sedimentology , Sedimentation and deposition
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5028 , http://hdl.handle.net/10962/d1006903
- Description: From Introduction: For at least two centuries and a corresponding number of generations of geologists and miners there has been active argument concerning the origin of certain types of carbonate hosted mineral deposit. The characterization of the type itself was and still is debatable. Objections have been raised to grouping several examples under one heading because each has its individually distinctive features. ·This is especially applicable to the carbonate hosted lead-zinc "sedimentary" deposits. The type that will be discussed in the text to follow is composed chiefly of galena, sphalerite, barite and fluorite, with pyrite , marcasite and chalcopyrite as conspicuous accessory ore minerals. Exceptions to this general copper deficient characteristic displayed by the sedimentary carbonate-hosted lead-zinc deposits are the deposits at Tsumeb and Kombat, Namibia. These deposits are hosted by the carbonate sequence of the Otavi Shelf sediments, and copper, in the form of tennantite, chalcopyrite and bornite, is the major ore constituent. Calcite, aragonite, dolomite and quartz are the commonest nonmetallic gangue minerals but siderite and silica may also be present. In contrast with other lead and zinc sulphide (volcanogenic) deposits, those to be considered here seldom carry noteworthy amounts of silver or any other precious metals. Commonly the country rock is a carbonate; limestone or dolomite, but deposits in. sandstone, shale and conglomerate are not unknown. Characteristic features are ore bodies that extend parallel or nearly so with the bedding although many such deposits are partly, or completely developed along crosscutting fissures and breccias. Some observers regard these fissure fillings as evidence for a magmatic source of the metals, whereas others regard them as an indication of remobilization of ions, metals or minerals orginally present in low-grade stratiform deposits elsewhere in the stratigraphic succession.
- Full Text:
Rhodes University 1981 Graduation Ceremonies Address
- Authors: Henderson, Derek Scott
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:7428 , http://hdl.handle.net/10962/d1018305
- Full Text:
- Authors: Henderson, Derek Scott
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:7428 , http://hdl.handle.net/10962/d1018305
- Full Text:
Rhodes University Graduation Ceremony 1981
- Authors: Rhodes University
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:8118 , http://hdl.handle.net/10962/d1004897
- Description: Rhodes University Graduation Ceremony on Friday, 10 April 1981 at 8 p.m. [and] on Saturday, 11 April 1981 at 10 a.m. in the 1820 Settlers National Monument.
- Full Text:
- Authors: Rhodes University
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:8118 , http://hdl.handle.net/10962/d1004897
- Description: Rhodes University Graduation Ceremony on Friday, 10 April 1981 at 8 p.m. [and] on Saturday, 11 April 1981 at 10 a.m. in the 1820 Settlers National Monument.
- Full Text:
Résultats des études menées en Angleterre: détermination de la posologie optimale
- Woodford, R, Haigh, John M, Barry, B W
- Authors: Woodford, R , Haigh, John M , Barry, B W
- Date: 1981
- Language: French
- Type: Article
- Identifier: vital:6449 , http://hdl.handle.net/10962/d1006636
- Description: Les auteurs ont etudie la biodisponibilite et I'activite de formules experimentales et commercialisees de dermocortico'ides en utilisant les essais de vasoconstriction avec et sans occlusion (1, 2, 6, 7, 8, 9). L'application unique de six heures avec lectures multiples a ete largement utilisee dans ce travail et la methodologie en a ete decrite en detail ailleurs (4). Sur la base de ce travail. on a pratique des applications repetees de dermocortico'ides commercialises au Royaume- Uni. en utilisant Ie test du blanchiment de la peau sans occlusion, de maniere a reproduire au plus pres la situation realisee en clinique (3). Ce travail a montre que I'application de cortico'ides trois fois par jour pendant cinq jours aboutissait a une tachyphylaxie considerable de la reponse du blanchiment quelque soit I'activite therapeutique de la formule utilisee. Au bout de deux jours de repos, on a assiste a une recuperation considerable, mais a nouveau une tachyphylaxie aigue s'est installee a la suite d'une nouvelle application triquotidienne.
- Full Text:
- Authors: Woodford, R , Haigh, John M , Barry, B W
- Date: 1981
- Language: French
- Type: Article
- Identifier: vital:6449 , http://hdl.handle.net/10962/d1006636
- Description: Les auteurs ont etudie la biodisponibilite et I'activite de formules experimentales et commercialisees de dermocortico'ides en utilisant les essais de vasoconstriction avec et sans occlusion (1, 2, 6, 7, 8, 9). L'application unique de six heures avec lectures multiples a ete largement utilisee dans ce travail et la methodologie en a ete decrite en detail ailleurs (4). Sur la base de ce travail. on a pratique des applications repetees de dermocortico'ides commercialises au Royaume- Uni. en utilisant Ie test du blanchiment de la peau sans occlusion, de maniere a reproduire au plus pres la situation realisee en clinique (3). Ce travail a montre que I'application de cortico'ides trois fois par jour pendant cinq jours aboutissait a une tachyphylaxie considerable de la reponse du blanchiment quelque soit I'activite therapeutique de la formule utilisee. Au bout de deux jours de repos, on a assiste a une recuperation considerable, mais a nouveau une tachyphylaxie aigue s'est installee a la suite d'une nouvelle application triquotidienne.
- Full Text:
Sampling in the evaluation of ore deposits
- Authors: Grant, D E C S
- Date: 1981 , 2013-03-19
- Subjects: Ore deposits , Mine valuation , Ores -- Sampling and estimation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5008 , http://hdl.handle.net/10962/d1005912 , Ore deposits , Mine valuation , Ores -- Sampling and estimation
- Description: Sampling is an error generating process and these errors should be reduced to a minimum if an accurate ore reserve estimation is to be made from the sample values. Error in sampling can arise from the sampling procedure as well as where and how each sample is taken from the deposit . Sampling procedure involves sample collection, sample reduction and analysis, and the error from each of these three stages has an equal influence on the total error of the process. Error due to sampling procedure should be identified and eliminated at an early stage in the evaluation programme. An ore deposit should be subdivided into sampling strata along geological boundaries, and once these boundaries have been established they should be adhered to for the evaluation programme. The sampling of each stratum depends on the small-scale structures in which the grade is distributed, and this distribution in relation to sample size controls sample variance, sample bias and the volume of influence of each sample. Cluster sampling can be used where an impractically large sample is necessary to reduce sample variance or increase the volume of influence of samples. Sample bias can be reduced by composing a large number of small samples . Sampling patterns should be designed with reference to the volumes of influence of samples, and in favourable geology, geostatistical or statistical techniques can be used to predict the precision of an ore reserve estimation 1n terms of the number of samples taken. Different are deposits have different sampling characteristics and problems which can be directly related to the geology of the mineralization. If geology is disregarded when sampling an are deposit, an evaluation programme cannot claim to give an accurate estimate of the ore reserves .
- Full Text:
- Authors: Grant, D E C S
- Date: 1981 , 2013-03-19
- Subjects: Ore deposits , Mine valuation , Ores -- Sampling and estimation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5008 , http://hdl.handle.net/10962/d1005912 , Ore deposits , Mine valuation , Ores -- Sampling and estimation
- Description: Sampling is an error generating process and these errors should be reduced to a minimum if an accurate ore reserve estimation is to be made from the sample values. Error in sampling can arise from the sampling procedure as well as where and how each sample is taken from the deposit . Sampling procedure involves sample collection, sample reduction and analysis, and the error from each of these three stages has an equal influence on the total error of the process. Error due to sampling procedure should be identified and eliminated at an early stage in the evaluation programme. An ore deposit should be subdivided into sampling strata along geological boundaries, and once these boundaries have been established they should be adhered to for the evaluation programme. The sampling of each stratum depends on the small-scale structures in which the grade is distributed, and this distribution in relation to sample size controls sample variance, sample bias and the volume of influence of each sample. Cluster sampling can be used where an impractically large sample is necessary to reduce sample variance or increase the volume of influence of samples. Sample bias can be reduced by composing a large number of small samples . Sampling patterns should be designed with reference to the volumes of influence of samples, and in favourable geology, geostatistical or statistical techniques can be used to predict the precision of an ore reserve estimation 1n terms of the number of samples taken. Different are deposits have different sampling characteristics and problems which can be directly related to the geology of the mineralization. If geology is disregarded when sampling an are deposit, an evaluation programme cannot claim to give an accurate estimate of the ore reserves .
- Full Text:
Schizophrenia and mysticism: a conceptual analysis
- Authors: Hammond, Carol Anne
- Date: 1981
- Subjects: Schizophrenia , Mysticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3129 , http://hdl.handle.net/10962/d1006348 , Schizophrenia , Mysticism
- Description: From introduction: The aim of this thesis is to explore the "queer relationship'" existing between mysticism and madness as it emerges from psychological writings and to examine and re-evaluate the life of Joan of Arc in terms of the conceptual framework that emerges.
- Full Text:
- Authors: Hammond, Carol Anne
- Date: 1981
- Subjects: Schizophrenia , Mysticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3129 , http://hdl.handle.net/10962/d1006348 , Schizophrenia , Mysticism
- Description: From introduction: The aim of this thesis is to explore the "queer relationship'" existing between mysticism and madness as it emerges from psychological writings and to examine and re-evaluate the life of Joan of Arc in terms of the conceptual framework that emerges.
- Full Text:
Separation and characterisation of chromium (III) carboxylate solutions
- Bryson, Michael Andrew Walker
- Authors: Bryson, Michael Andrew Walker
- Date: 1981
- Subjects: Chromium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4416 , http://hdl.handle.net/10962/d1006847
- Description: From Summary: The complexes present in chromium(III) carboxylate solutions (acetate or formate) were separated using ion exchange chromatography, electrophoresis and gel filtration. Eight cationic species and one non-ionic species with charges from 0 to +3 and nuclearities ranging from mononuclear to quadranuclear were isolated from chromium(III) acetate solutions. Six cationic species with charges from +1 to +3 and nuclearities ranging from mononuclear to trinuclear were isolated from chromium(III) formate solutions. The empirical formulae for these complexes were determined by analytical methods. Infra- red spectroscopy was used to distinguish between monodentate and bidentate bridged carboxylate ligands. An immediate change in the visible spectrum of a complex on its acidification was used as evidence that a terminal hydroxo group was present.
- Full Text:
- Authors: Bryson, Michael Andrew Walker
- Date: 1981
- Subjects: Chromium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4416 , http://hdl.handle.net/10962/d1006847
- Description: From Summary: The complexes present in chromium(III) carboxylate solutions (acetate or formate) were separated using ion exchange chromatography, electrophoresis and gel filtration. Eight cationic species and one non-ionic species with charges from 0 to +3 and nuclearities ranging from mononuclear to quadranuclear were isolated from chromium(III) acetate solutions. Six cationic species with charges from +1 to +3 and nuclearities ranging from mononuclear to trinuclear were isolated from chromium(III) formate solutions. The empirical formulae for these complexes were determined by analytical methods. Infra- red spectroscopy was used to distinguish between monodentate and bidentate bridged carboxylate ligands. An immediate change in the visible spectrum of a complex on its acidification was used as evidence that a terminal hydroxo group was present.
- Full Text:
Some aspects of housing economics with reference to the coloured population of South Africa
- Authors: Farabi, Sadraddin
- Date: 1981 , 2013-04-02
- Subjects: Housing -- South Africa , Housing policy -- South Africa , Regional economics -- South Africa , Economic development -- South Africa , Colored people (South Africa) -- Housing , Colored people (South Africa) -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:1050 , http://hdl.handle.net/10962/d1006342 , Housing -- South Africa , Housing policy -- South Africa , Regional economics -- South Africa , Economic development -- South Africa , Colored people (South Africa) -- Housing , Colored people (South Africa) -- South Africa -- Grahamstown
- Full Text:
- Authors: Farabi, Sadraddin
- Date: 1981 , 2013-04-02
- Subjects: Housing -- South Africa , Housing policy -- South Africa , Regional economics -- South Africa , Economic development -- South Africa , Colored people (South Africa) -- Housing , Colored people (South Africa) -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:1050 , http://hdl.handle.net/10962/d1006342 , Housing -- South Africa , Housing policy -- South Africa , Regional economics -- South Africa , Economic development -- South Africa , Colored people (South Africa) -- Housing , Colored people (South Africa) -- South Africa -- Grahamstown
- Full Text:
Some aspects of the biology of Nassarius kraussianus (Dunker)(Gastropoda : Prosobranchia : Nassariidae), in the Bushman's River estuary, with particular reference to recolonisation after floods
- Authors: Palmer, Carolyn Gay
- Date: 1981
- Subjects: Gastropoda -- South Africa -- Eastern Cape , Estuarine biology -- South Africa -- Eastern Cape , Prosobranchia -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5809 , http://hdl.handle.net/10962/d1006934 , Gastropoda -- South Africa -- Eastern Cape , Estuarine biology -- South Africa -- Eastern Cape , Prosobranchia -- South Africa -- Eastern Cape
- Description: 1. The development of estuarine research in South Africa has been reviewed, and the present state of knowledge assessed. Little is known about many abundant estuarine species, and a previously unstudied prosobranch Nassarius kraussianus (Dunker), was selected for investigation. 2. The study area, a mudflat on the Bushmans River estuary, was divided into three habitat types: supratidal, intertidal and subtidal, each with a particular substratum and pattern of vegetation cover. The distribution of N. kraussianus is associated with the nature of the substratum and the degree of Zostera capensis Setchell cover. 3. A brief review of pertinent literature indicated the necessity of relating population parameters to environmental conditions. 4. The population biology of N. . kraussianus was investigated, and the size frequencies, sex ratios, and male/female size frequencies were recorded over three distinct periods: pre-flood, post-flood and recovery. 5. The Bushmans River flooded in July and August 1979, and the results of the flood have been described. The most immediate result was a period of low salinity, but the most persistant result was the deposition of silt, which had an important effect on the substratum and the Z. capensis beds. 6. The pre-flood population was characterised by patchy distribution, and by a large number of mature adults in relation to juveniles. Females were generally larger than males, and the sex ratio was 1:1. The presence of juveniles in consistantly low numbers indicated that reproduction may have been continuous, but that intraspecific adult/juvenile competition may have kept juvenile numbers low. 7. The post-flood period was characterised by extreme physical conditions, and the survival of a few adults. Juveniles were completely annihilated, and were absent until a few were spawned by the surviving adults towards the end of 1979 . Sex ratio was biased, and females predominated. 8. The recovery period began abruptly with the arrival of a large number of juveniles in the 2, 3 and 4 mm size classes. Recolonisation coincided with habitat recovery, and reqeneration of the Z. capensis cover. Recolonising juveniles grew quickly, reaching adult size in three months. After that, juveniles were spawned on the mudflat by the new population. During this period the sex ratio did not return to the pre-flood 1:1, but remained female biased. Males and females grew at the same rate over the period measured, but females were consistantly larger, indicating that at some stage female growth may be faster. 9. The recolonising juveniles arrived in a regenerated habitat, at a time when temperatures were high, and conditions for growth probably optimal. If intraspecific competition was a feature of the pre-flood population it would have been elimianted in the recovery phase, by the absence of adults. 10. N. kraussianus is apparently omnivorous and proabably not food limited. However, carrion, a limited resource, may be essential for growth to reproductive maturity. Adults and juveniles may compete for this resource, and any juveniles deprived of access to carrion may be stimulated to leave the parental habitat. 11. N. kraussianus is ovoviviparous, and carries up to 5 egg cases within the uterus. Each triangular egg case contains 1 egg which hatches after approximately 3 weeks, as a free swimming veliger. Yeligers metamorphose, and settle after 4-7 days, assuming a benthic mode of life. Ovoviviparity protects the developing embryo from the rigours of environmental extremes, and ensures that embryos are not swept out to sea . Additionally, veligers have a high probability of settling in the parental habitat. 12. This reproductive strategy has been compared with other prosobranchs, and the evolutionary trends within the Prosobranchia, and particularly the Nassariidae, have been related to their dispersal potential. 13. Developmental strategy is intimately related to recolonisation potential. Ovoviviparity, and the lack of pelagic larvae, did not limit the recolonisation potential of N. kraussianus, and recolonisation was probably effected by post-larval juveniles, which may disperse from neighbouring estuaries and coastal pools, by floating in coastal and tidal currents. Post-larval juveniles have two important advantages over larvae. They are less vulnerable to physical extremes, and they have a sturdy crennellated shell which probably affords them protection from predators. 14. Examples of larval recolonisation in estuarine populations have been reviewed, and the most fundamental conclusion of this work is that recolonisation is an important, and probably widespread, adaptation to estuarine conditions in South Africa.
- Full Text:
- Authors: Palmer, Carolyn Gay
- Date: 1981
- Subjects: Gastropoda -- South Africa -- Eastern Cape , Estuarine biology -- South Africa -- Eastern Cape , Prosobranchia -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5809 , http://hdl.handle.net/10962/d1006934 , Gastropoda -- South Africa -- Eastern Cape , Estuarine biology -- South Africa -- Eastern Cape , Prosobranchia -- South Africa -- Eastern Cape
- Description: 1. The development of estuarine research in South Africa has been reviewed, and the present state of knowledge assessed. Little is known about many abundant estuarine species, and a previously unstudied prosobranch Nassarius kraussianus (Dunker), was selected for investigation. 2. The study area, a mudflat on the Bushmans River estuary, was divided into three habitat types: supratidal, intertidal and subtidal, each with a particular substratum and pattern of vegetation cover. The distribution of N. kraussianus is associated with the nature of the substratum and the degree of Zostera capensis Setchell cover. 3. A brief review of pertinent literature indicated the necessity of relating population parameters to environmental conditions. 4. The population biology of N. . kraussianus was investigated, and the size frequencies, sex ratios, and male/female size frequencies were recorded over three distinct periods: pre-flood, post-flood and recovery. 5. The Bushmans River flooded in July and August 1979, and the results of the flood have been described. The most immediate result was a period of low salinity, but the most persistant result was the deposition of silt, which had an important effect on the substratum and the Z. capensis beds. 6. The pre-flood population was characterised by patchy distribution, and by a large number of mature adults in relation to juveniles. Females were generally larger than males, and the sex ratio was 1:1. The presence of juveniles in consistantly low numbers indicated that reproduction may have been continuous, but that intraspecific adult/juvenile competition may have kept juvenile numbers low. 7. The post-flood period was characterised by extreme physical conditions, and the survival of a few adults. Juveniles were completely annihilated, and were absent until a few were spawned by the surviving adults towards the end of 1979 . Sex ratio was biased, and females predominated. 8. The recovery period began abruptly with the arrival of a large number of juveniles in the 2, 3 and 4 mm size classes. Recolonisation coincided with habitat recovery, and reqeneration of the Z. capensis cover. Recolonising juveniles grew quickly, reaching adult size in three months. After that, juveniles were spawned on the mudflat by the new population. During this period the sex ratio did not return to the pre-flood 1:1, but remained female biased. Males and females grew at the same rate over the period measured, but females were consistantly larger, indicating that at some stage female growth may be faster. 9. The recolonising juveniles arrived in a regenerated habitat, at a time when temperatures were high, and conditions for growth probably optimal. If intraspecific competition was a feature of the pre-flood population it would have been elimianted in the recovery phase, by the absence of adults. 10. N. kraussianus is apparently omnivorous and proabably not food limited. However, carrion, a limited resource, may be essential for growth to reproductive maturity. Adults and juveniles may compete for this resource, and any juveniles deprived of access to carrion may be stimulated to leave the parental habitat. 11. N. kraussianus is ovoviviparous, and carries up to 5 egg cases within the uterus. Each triangular egg case contains 1 egg which hatches after approximately 3 weeks, as a free swimming veliger. Yeligers metamorphose, and settle after 4-7 days, assuming a benthic mode of life. Ovoviviparity protects the developing embryo from the rigours of environmental extremes, and ensures that embryos are not swept out to sea . Additionally, veligers have a high probability of settling in the parental habitat. 12. This reproductive strategy has been compared with other prosobranchs, and the evolutionary trends within the Prosobranchia, and particularly the Nassariidae, have been related to their dispersal potential. 13. Developmental strategy is intimately related to recolonisation potential. Ovoviviparity, and the lack of pelagic larvae, did not limit the recolonisation potential of N. kraussianus, and recolonisation was probably effected by post-larval juveniles, which may disperse from neighbouring estuaries and coastal pools, by floating in coastal and tidal currents. Post-larval juveniles have two important advantages over larvae. They are less vulnerable to physical extremes, and they have a sturdy crennellated shell which probably affords them protection from predators. 14. Examples of larval recolonisation in estuarine populations have been reviewed, and the most fundamental conclusion of this work is that recolonisation is an important, and probably widespread, adaptation to estuarine conditions in South Africa.
- Full Text:
Some aspects of the reproductive endocrinology of the catfish, Clarias Gariepinus (Burchell, 1822)
- Authors: Rennie, Susan Elizabeth
- Date: 1981
- Subjects: Catfishes Clarias gariepinus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5339 , http://hdl.handle.net/10962/d1005924
- Description: A description is given of the location, anatomy and morphology of the endocrine glands likely to be involved in controlling the reproductive cycle of C. gariepinus. Methods of identifying the secretory tissues in the light and electron microscopes are outlined. A review of the published results on homologous tissues from other teleosts is included and directions for further research on the endocrinology of C. gariepinus are discussed.
- Full Text:
- Authors: Rennie, Susan Elizabeth
- Date: 1981
- Subjects: Catfishes Clarias gariepinus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5339 , http://hdl.handle.net/10962/d1005924
- Description: A description is given of the location, anatomy and morphology of the endocrine glands likely to be involved in controlling the reproductive cycle of C. gariepinus. Methods of identifying the secretory tissues in the light and electron microscopes are outlined. A review of the published results on homologous tissues from other teleosts is included and directions for further research on the endocrinology of C. gariepinus are discussed.
- Full Text:
South Africa, the prospects of peaceful change: an empirical enquiry into the possibility of democratic conflict regulation
- Hanf, Theodor, 1936-, Weiland, Heribert, 1942-, Vierdag, Gerda, Schlemmer, Lawrence 1936-2011, Hampel, Rainer, Krupp, Burkhard, Richardson, John, Orkin, Mark
- Authors: Hanf, Theodor, 1936- , Weiland, Heribert, 1942- , Vierdag, Gerda , Schlemmer, Lawrence 1936-2011 , Hampel, Rainer , Krupp, Burkhard , Richardson, John , Orkin, Mark
- Date: 1981 , 2021
- Subjects: South Africa Race relations , South Africa Politics and government 1961-1978
- Language: English
- Type: Book , text
- Identifier: http://hdl.handle.net/10962/179720 , vital:43164
- Description: Our aim in this book is not to tell black or white South Africans what they ought to do. Rather, we try to establish through empirical social research what the various groups would like to do, and what they are in fact able to do. The overall issue which we consider is whether conflict can be regulated both peacefully and democratically. The events of 1976 and 1977 established beyond doubt that conflict exists on a large scale in South Africa. The conflict is both open and latent. Its causes include the distribution of income and wealth between different groups, the enforced social segregation of the groups from each other, and the monopoly of power by one of the groups. This one group has used and continues to use its power to regulate the conflict, and does so unilaterally and towards its own ends. Now conflict can be regulated in this way for a considerable period of time—longer than the whites dare hope and the blacks concede. But it is unlikely that power can be exercised indefinitely without the consent of the majority. Indeed, the longer a group exercises power without consent, the more likely is violent change. Given the distribution of power in contemporary South Africa, violent change would involve enormous sacrifices all round. So we consider the chances of peaceful change. Unfortunately, the chances seem slim. A glance at history shows that minorities tend to cling obstinately to their privileges, and then lose everything in defending them. One is far less likely to find minorities who have made timely sacrifices of some things in order to hold onto others. Similarly, once the tables are turned, the majorities that have been exploited and maltreated more often give vent to their long-suppressed feelings of hate and revenge than explore the possibilities for a peaceful take-over of power. Even so, however likely such developments may be when seen from a historical perspective, there is no ‘iron law of history’ which categorically excludes the possibility of peaceful change under the conditions obtaining in South Africa. And the ‘social costs’—a euphemism in social science for human suffering—of violent change are so high that one is surely justified in exploring the constraints, however narrow they might be, within which the current system of conflict regulation in South Africa might be peacefully transformed. This consideration is even more important in the present global political situation; for change by violent means will not only endanger the parties directly concerned, but may also endanger the peace of the African continent and perhaps that of the rest of the world. We also want to know whether conflict can be regulated democratically. We assume that the rule of law, social justice, and democratic rights are not the prerogatives of wealthy Western states. We believe that all the members of a society should be able to decide freely on how they want to shape their economic, cultural, and political coexistence. This study is thus motivated by a specific interest: we want to ascertain what scope there is in contemporary South Africa for changing the existing system of domination, so as to allow the democratic regulation of conflict, more social justice, a greater diversity of cultural expression, and wider freedom for all South Africans. We stress that we are concerned with the democratic regulation of conflict. For this purpose, the context in which conflict originated in South Africa is only relevant to the extent that it may still influence the present situation. Similarly, explanations of the phenomenon of conflict will be relevant only if they let us formulate more precisely the problem of how conflict may be peacefully and democratically regulated. This problem is important not because it contributes to the progress of social science—that contribution may be modest—but because it bears on the fate of many human beings. We have tried to offer answers which can be supported by empirical inquiry. Although the literature on conflict regulation in South Africa has expanded rapidly in recent years, it is characterized by a lack of empirical data on the attitudes and opinions of the groups and individuals involved in the political process. We felt it would be useful if we lessened these gaps in our knowledge by empirical means. But data on the attitudes and opinions of black and white South Africans are hardly a sufficient basis for reliable predictions about South Africa’s future. Events in South Africa will not only be determined by the opinions and wishes of its inhabitants but also, as is becoming increasingly evident, by forces and influences outside the country. However, the latter have been expressly excluded from the present study; it is concerned, ceteris paribus, with internal South African developments. But even with respect to internal developments, what actually happens in a society is only partly determined by what the members of the society think and want. It would thus be foolhardy to base a comprehensive prognostication on opinion surveys alone. On the other hand, empirical surveys may facilitate a precise answer to the overall problem we have set ourselves. Empirical research can indicate how far white South Africans are prepared for peaceful change and democratic conflict regulation, and similarly, what change black South Africans expect and what means of conflict regulation they are prepared to accept. Does the preparedness of the whites match or fall far short of the expectations of the blacks? The question is crucial to change without violence. Thus, in respect of our motivation and of the limitations we have set on the nature of our inquiry, this study must be seen as an empirical contribution to research into conflict and peace.
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- Authors: Hanf, Theodor, 1936- , Weiland, Heribert, 1942- , Vierdag, Gerda , Schlemmer, Lawrence 1936-2011 , Hampel, Rainer , Krupp, Burkhard , Richardson, John , Orkin, Mark
- Date: 1981 , 2021
- Subjects: South Africa Race relations , South Africa Politics and government 1961-1978
- Language: English
- Type: Book , text
- Identifier: http://hdl.handle.net/10962/179720 , vital:43164
- Description: Our aim in this book is not to tell black or white South Africans what they ought to do. Rather, we try to establish through empirical social research what the various groups would like to do, and what they are in fact able to do. The overall issue which we consider is whether conflict can be regulated both peacefully and democratically. The events of 1976 and 1977 established beyond doubt that conflict exists on a large scale in South Africa. The conflict is both open and latent. Its causes include the distribution of income and wealth between different groups, the enforced social segregation of the groups from each other, and the monopoly of power by one of the groups. This one group has used and continues to use its power to regulate the conflict, and does so unilaterally and towards its own ends. Now conflict can be regulated in this way for a considerable period of time—longer than the whites dare hope and the blacks concede. But it is unlikely that power can be exercised indefinitely without the consent of the majority. Indeed, the longer a group exercises power without consent, the more likely is violent change. Given the distribution of power in contemporary South Africa, violent change would involve enormous sacrifices all round. So we consider the chances of peaceful change. Unfortunately, the chances seem slim. A glance at history shows that minorities tend to cling obstinately to their privileges, and then lose everything in defending them. One is far less likely to find minorities who have made timely sacrifices of some things in order to hold onto others. Similarly, once the tables are turned, the majorities that have been exploited and maltreated more often give vent to their long-suppressed feelings of hate and revenge than explore the possibilities for a peaceful take-over of power. Even so, however likely such developments may be when seen from a historical perspective, there is no ‘iron law of history’ which categorically excludes the possibility of peaceful change under the conditions obtaining in South Africa. And the ‘social costs’—a euphemism in social science for human suffering—of violent change are so high that one is surely justified in exploring the constraints, however narrow they might be, within which the current system of conflict regulation in South Africa might be peacefully transformed. This consideration is even more important in the present global political situation; for change by violent means will not only endanger the parties directly concerned, but may also endanger the peace of the African continent and perhaps that of the rest of the world. We also want to know whether conflict can be regulated democratically. We assume that the rule of law, social justice, and democratic rights are not the prerogatives of wealthy Western states. We believe that all the members of a society should be able to decide freely on how they want to shape their economic, cultural, and political coexistence. This study is thus motivated by a specific interest: we want to ascertain what scope there is in contemporary South Africa for changing the existing system of domination, so as to allow the democratic regulation of conflict, more social justice, a greater diversity of cultural expression, and wider freedom for all South Africans. We stress that we are concerned with the democratic regulation of conflict. For this purpose, the context in which conflict originated in South Africa is only relevant to the extent that it may still influence the present situation. Similarly, explanations of the phenomenon of conflict will be relevant only if they let us formulate more precisely the problem of how conflict may be peacefully and democratically regulated. This problem is important not because it contributes to the progress of social science—that contribution may be modest—but because it bears on the fate of many human beings. We have tried to offer answers which can be supported by empirical inquiry. Although the literature on conflict regulation in South Africa has expanded rapidly in recent years, it is characterized by a lack of empirical data on the attitudes and opinions of the groups and individuals involved in the political process. We felt it would be useful if we lessened these gaps in our knowledge by empirical means. But data on the attitudes and opinions of black and white South Africans are hardly a sufficient basis for reliable predictions about South Africa’s future. Events in South Africa will not only be determined by the opinions and wishes of its inhabitants but also, as is becoming increasingly evident, by forces and influences outside the country. However, the latter have been expressly excluded from the present study; it is concerned, ceteris paribus, with internal South African developments. But even with respect to internal developments, what actually happens in a society is only partly determined by what the members of the society think and want. It would thus be foolhardy to base a comprehensive prognostication on opinion surveys alone. On the other hand, empirical surveys may facilitate a precise answer to the overall problem we have set ourselves. Empirical research can indicate how far white South Africans are prepared for peaceful change and democratic conflict regulation, and similarly, what change black South Africans expect and what means of conflict regulation they are prepared to accept. Does the preparedness of the whites match or fall far short of the expectations of the blacks? The question is crucial to change without violence. Thus, in respect of our motivation and of the limitations we have set on the nature of our inquiry, this study must be seen as an empirical contribution to research into conflict and peace.
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Speech Day Address, Port Shepstone High School, Wednesday, 11 November I981
- Authors: Henderson, Derek Scott
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:7440 , http://hdl.handle.net/10962/d1018317
- Full Text:
- Authors: Henderson, Derek Scott
- Date: 1981
- Language: English
- Type: text
- Identifier: vital:7440 , http://hdl.handle.net/10962/d1018317
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Studies on an autolysin produced by clostridium acetobutylicum
- Authors: Webster, Jocelyn Rowena
- Date: 1981
- Subjects: Clostridium acetobutylicum , Autolysis , Bacteriocins , Proteins -- Synthesis , DNA -- Synthesis , RNA -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3893 , http://hdl.handle.net/10962/d1003724
- Description: An extracellular bacteriocin-like substance produced by Clostridium acetobutylicum was detected during studies on an industrial fermentation process. The bacteriocin-like substance was not inducible by either ultraviolet light or mitomycin C, and its production was not associated with the induction of a protease. Studies on the mode of action of the bacteriocin-like substance indicated that it had no significant effect on DNA, RNA, or protein synthesis, and it did not cause the loss of intracellular ATP. However, the bacteriocin-like substance was able to lyse SDS-treated cells and cell walls of C. acetobutylicum and was identified as an autolysin. Some of the characteristics of this extracellular autolysin were determined, and after purification it was shown to be a glycoprotein with a molecular weight of 28 000.
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- Authors: Webster, Jocelyn Rowena
- Date: 1981
- Subjects: Clostridium acetobutylicum , Autolysis , Bacteriocins , Proteins -- Synthesis , DNA -- Synthesis , RNA -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3893 , http://hdl.handle.net/10962/d1003724
- Description: An extracellular bacteriocin-like substance produced by Clostridium acetobutylicum was detected during studies on an industrial fermentation process. The bacteriocin-like substance was not inducible by either ultraviolet light or mitomycin C, and its production was not associated with the induction of a protease. Studies on the mode of action of the bacteriocin-like substance indicated that it had no significant effect on DNA, RNA, or protein synthesis, and it did not cause the loss of intracellular ATP. However, the bacteriocin-like substance was able to lyse SDS-treated cells and cell walls of C. acetobutylicum and was identified as an autolysin. Some of the characteristics of this extracellular autolysin were determined, and after purification it was shown to be a glycoprotein with a molecular weight of 28 000.
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Tertiary phonolite volcanism in the Klinghardt Mountains of South West Africa/Namibia
- Authors: Marsh, Julian S , Lock, B E
- Date: 1981
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/133242 , vital:36953 , https://hdl.handle.net/10520/AJA10120750_2789
- Description: The Klinghardt Mountains in South West Africa (Namibia) were the site of an important volcanic outburst late in the Eocene or early in the Oligocene. Over a hundred endogenous domes and several lava flows of the coulee type were emplaced: all analysed samples (more than 60) comprise varieties of phonolite. A sequence of ash-flow tuffs of limited areal extent is present on Glasrucken.
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- Authors: Marsh, Julian S , Lock, B E
- Date: 1981
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/133242 , vital:36953 , https://hdl.handle.net/10520/AJA10120750_2789
- Description: The Klinghardt Mountains in South West Africa (Namibia) were the site of an important volcanic outburst late in the Eocene or early in the Oligocene. Over a hundred endogenous domes and several lava flows of the coulee type were emplaced: all analysed samples (more than 60) comprise varieties of phonolite. A sequence of ash-flow tuffs of limited areal extent is present on Glasrucken.
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The church music of Felix Mendelssohn-Bartholdy :|ban investigation into formal and stylistic aspects of his organ and sacred choral works
- Authors: Johnson, Bruce Richard
- Date: 1981
- Subjects: Mendelssohn-Bartholdy, Felix, 1809-1847 Church music
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2669 , http://hdl.handle.net/10962/d1006880
- Full Text:
- Authors: Johnson, Bruce Richard
- Date: 1981
- Subjects: Mendelssohn-Bartholdy, Felix, 1809-1847 Church music
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2669 , http://hdl.handle.net/10962/d1006880
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The comparative bioavailability and in vitro assessment of solid oral dosage forms of paracetamol
- Authors: Braae, Karen
- Date: 1981 , 2013-04-02
- Subjects: Acetaminophen , Bioavailability , Drugs -- Bioavailability , Drugs -- Dosage forms , Analysis of variance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3827 , http://hdl.handle.net/10962/d1006288 , Acetaminophen , Bioavailability , Drugs -- Bioavailability , Drugs -- Dosage forms , Analysis of variance
- Description: The dissolution profiles of eight lots of paracetamol tablets representing seven different tablet brands are determined in a USP rotating basket assembly and a stationary basket-rotating paddle apparatus. The in vitro data are expressed in terms of dissolution parameters and inter-tablet differences are assessed statistically using analysis of variance (ANOVA) and the Scheffe test. Highly significant differences are observed between a number of the tablets at the 95% confidence level. Representative tablets from the dissolution rate study and a control dose of paracetamol dissolved in water are subsequently investigated in a 4 x 4 latin square design bioavailability trial. Serum and urine samples are collected and assayed for paracetamol alone (serum) and together with its metabolites (urine) by means of high pressure liquid chromatography. The in vivo data are expressed in terms of bioavailability parameters and differences between the test doses are assessed by means of ANOVA. No significant differences are observed between the dosage forms at the 95% confidence level.
- Full Text:
- Authors: Braae, Karen
- Date: 1981 , 2013-04-02
- Subjects: Acetaminophen , Bioavailability , Drugs -- Bioavailability , Drugs -- Dosage forms , Analysis of variance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3827 , http://hdl.handle.net/10962/d1006288 , Acetaminophen , Bioavailability , Drugs -- Bioavailability , Drugs -- Dosage forms , Analysis of variance
- Description: The dissolution profiles of eight lots of paracetamol tablets representing seven different tablet brands are determined in a USP rotating basket assembly and a stationary basket-rotating paddle apparatus. The in vitro data are expressed in terms of dissolution parameters and inter-tablet differences are assessed statistically using analysis of variance (ANOVA) and the Scheffe test. Highly significant differences are observed between a number of the tablets at the 95% confidence level. Representative tablets from the dissolution rate study and a control dose of paracetamol dissolved in water are subsequently investigated in a 4 x 4 latin square design bioavailability trial. Serum and urine samples are collected and assayed for paracetamol alone (serum) and together with its metabolites (urine) by means of high pressure liquid chromatography. The in vivo data are expressed in terms of bioavailability parameters and differences between the test doses are assessed by means of ANOVA. No significant differences are observed between the dosage forms at the 95% confidence level.
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The determination of God's action in history with special reference to Herbert Butterfield
- Authors: Fourie, Stephen
- Date: 1981
- Subjects: Butterfield, Herbert, 1900-1979 Christianity -- Philosophy -- History God -- History of doctrines
- Language: English
- Type: Thesis , Bachelor , BDiv
- Identifier: vital:1242 , http://hdl.handle.net/10962/d1009438
- Full Text:
- Authors: Fourie, Stephen
- Date: 1981
- Subjects: Butterfield, Herbert, 1900-1979 Christianity -- Philosophy -- History God -- History of doctrines
- Language: English
- Type: Thesis , Bachelor , BDiv
- Identifier: vital:1242 , http://hdl.handle.net/10962/d1009438
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The diary of James Brownlee
- Brown, Alastair Graham Kirkwood
- Authors: Brown, Alastair Graham Kirkwood
- Date: 1981
- Subjects: Brownlee, James, 1824-1851 -- Diaries , South Africa -- History -- Frontier Wars, 1811-1878
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2598 , http://hdl.handle.net/10962/d1007678 , Brownlee, James, 1824-1851 -- Diaries , South Africa -- History -- Frontier Wars, 1811-1878
- Description: James Brownlee was born in April 1824. He was the second of three sons (and five daughters) born to the missionary John Brownlee, and his colonial born wife Catharine. The importance of James as an historical character is obscured by that of his father and elder brother Charles. James had a varied career which was cut short by his untimely death in March 1851 at the youthful age of twenty-six years and eleven months. We are fortunate that he has left a vivid account of several aspects of the seventh Frontier War in a diary which he kept from April to September 1846. The diary also points to the significance of his family in the history of the Eastern Cape. Thesis, p. 1.
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- Authors: Brown, Alastair Graham Kirkwood
- Date: 1981
- Subjects: Brownlee, James, 1824-1851 -- Diaries , South Africa -- History -- Frontier Wars, 1811-1878
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2598 , http://hdl.handle.net/10962/d1007678 , Brownlee, James, 1824-1851 -- Diaries , South Africa -- History -- Frontier Wars, 1811-1878
- Description: James Brownlee was born in April 1824. He was the second of three sons (and five daughters) born to the missionary John Brownlee, and his colonial born wife Catharine. The importance of James as an historical character is obscured by that of his father and elder brother Charles. James had a varied career which was cut short by his untimely death in March 1851 at the youthful age of twenty-six years and eleven months. We are fortunate that he has left a vivid account of several aspects of the seventh Frontier War in a diary which he kept from April to September 1846. The diary also points to the significance of his family in the history of the Eastern Cape. Thesis, p. 1.
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The economic geology of the Okiep copper deposits, Namaqualand, South Africa
- Authors: Gadd-Claxton, D L
- Date: 1981 , 2013-04-04
- Subjects: Geology, Economic -- South Africa -- Okiep , Copper ores -- South Africa -- Okiep , Okiep (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4923 , http://hdl.handle.net/10962/d1004507 , Geology, Economic -- South Africa -- Okiep , Copper ores -- South Africa -- Okiep , Okiep (South Africa)
- Description: The Okiep Copper District situated in the north-western Cape Province, covers some 3 000 km and is the oldest mining area in the Republic of South Africa. The O'okiep Copper Company Limited commenced production in 1940 with a proven ore reserve of 9 million tons at 2,45 % cu. Production since 1940 and present ore reserves total some 93 million tonnes at 1,08 % Cu. The rocks comprising the Okiep Copper District are of Proterozoic age and have been subdivided into a meta-volcanosedimentary succession, intruded by various sub-horizontally emplaced granitoid intrusions. The various intrusions occurred at different stages relative to the main structural and metamorphic events. The copper deposits are confined to basic rocks which are the youngest major group of intrusives in the District. They occur as swarms of generally easterly-trending, steep northdipping, irregular dyke-like bodies consisting of diorite, anorthosite and norite. The dominant silicate constituents are andesite ranging to labradorite, hypersthene, biotite and phlogopite. Copper sulphides are preferentially associated with the more basic varieties. The copper sulphides are mainly chalcopyrite, bornite and subsidiary chalcocite. The copper content of the basic rocks is erratic ranging over small distances from a mere trace to several percent. Emplacement of the cupriferous basic rocks is predisposed to a large extent by enigmatic structural features locally referred to as steep structures. The most common manifestation of steep structure deformation is typically a narrow antiformal linear feature along which continuity of the country rocks has been interrupted by piercement folding and shearing. In places, pipelike bodies of megabreccia occur along steep structures, and also act as hosts to the basic rock. Areas of steep structure are thus prime exploration targets, due to their close spatial association with the cupriferous basic rocks. Exploration techiques employed in the Okiep Copper District in~ elude regional and detailed geological mapping, geophysical surveys utilizing magnetic, gravimetric and electrical methods, as well as limited application of soil and stream-sediment geochemistry. Final evaluation is by surface and underground diamond drilling. Exploration has to date discovered 18 new mines with individual ore reserves ranging from 200 000 to 37 000 000 tonnes. All are underground operations, and the sub-level open stoping method of mining is standard.
- Full Text:
- Authors: Gadd-Claxton, D L
- Date: 1981 , 2013-04-04
- Subjects: Geology, Economic -- South Africa -- Okiep , Copper ores -- South Africa -- Okiep , Okiep (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4923 , http://hdl.handle.net/10962/d1004507 , Geology, Economic -- South Africa -- Okiep , Copper ores -- South Africa -- Okiep , Okiep (South Africa)
- Description: The Okiep Copper District situated in the north-western Cape Province, covers some 3 000 km and is the oldest mining area in the Republic of South Africa. The O'okiep Copper Company Limited commenced production in 1940 with a proven ore reserve of 9 million tons at 2,45 % cu. Production since 1940 and present ore reserves total some 93 million tonnes at 1,08 % Cu. The rocks comprising the Okiep Copper District are of Proterozoic age and have been subdivided into a meta-volcanosedimentary succession, intruded by various sub-horizontally emplaced granitoid intrusions. The various intrusions occurred at different stages relative to the main structural and metamorphic events. The copper deposits are confined to basic rocks which are the youngest major group of intrusives in the District. They occur as swarms of generally easterly-trending, steep northdipping, irregular dyke-like bodies consisting of diorite, anorthosite and norite. The dominant silicate constituents are andesite ranging to labradorite, hypersthene, biotite and phlogopite. Copper sulphides are preferentially associated with the more basic varieties. The copper sulphides are mainly chalcopyrite, bornite and subsidiary chalcocite. The copper content of the basic rocks is erratic ranging over small distances from a mere trace to several percent. Emplacement of the cupriferous basic rocks is predisposed to a large extent by enigmatic structural features locally referred to as steep structures. The most common manifestation of steep structure deformation is typically a narrow antiformal linear feature along which continuity of the country rocks has been interrupted by piercement folding and shearing. In places, pipelike bodies of megabreccia occur along steep structures, and also act as hosts to the basic rock. Areas of steep structure are thus prime exploration targets, due to their close spatial association with the cupriferous basic rocks. Exploration techiques employed in the Okiep Copper District in~ elude regional and detailed geological mapping, geophysical surveys utilizing magnetic, gravimetric and electrical methods, as well as limited application of soil and stream-sediment geochemistry. Final evaluation is by surface and underground diamond drilling. Exploration has to date discovered 18 new mines with individual ore reserves ranging from 200 000 to 37 000 000 tonnes. All are underground operations, and the sub-level open stoping method of mining is standard.
- Full Text: