Magma flow inferred from AMS fabrics in a layered mafic sill, Insizwa, South Africa
- Ferré, Eric C, Bordarier, Cecile, Marsh, Julian S
- Authors: Ferré, Eric C , Bordarier, Cecile , Marsh, Julian S
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6733 , http://hdl.handle.net/10962/d1007543
- Description: The Insizwa sill, is a 25-km-diameter, >1000-m-thick layered mafic intrusion, part of the Karoo Igneous Province in South Africa. The peridotitic and gabbronoritic rocks are undeformed and mineral fabrics demonstrably result from magma flow. A horizontal, centimeter-scale model layering is visible in numerous outcrops. Plagioclase crystals are both tabular and elongated. Their preferred orientation, parallel to the layering, forms a foliation and a NW–SE lineation, respectively interpreted as the magma flow plane and flow direction. Throughout the 78 stations of this study (699 specimens), magnetic susceptibilities (K[subscript m]) range from 750 to 10,000×10[superscript (−6)] SI. The magnetic anisotropy (P[subscript j]) ranges from 1.03 to 1.08. Magnetic ellipsoids are both prolate and oblate (average T[subscript j]≈0). Anisotropy of magnetic susceptibility (AMS) fabrics are dominated by multidomain to pseudo-single domain magnetite. High-field magnetic experiments indicate that the paramagnetic contribution from the mafic silicates is less than 50 percentage for low susceptibility rock types. The anisotropy results from magnetite grain shape solely as shown by no significant increase in P[subscript j] with increasing K[subscript m]. The magnetic lineation (305°, 05°) is consistent throughout the sill at various scales and coincides with the mineral lineation in average. In contrast, the magnetic foliation (125° NE 10°) is generally perpendicular to the mineral foliation and to the layering. Several explanations for this odd configuration are discussed. The variations of magnetic parameters across the layering and field observations point to a multiple injection. The magnetic lineation is consistent with the presence of a single feeder dike situated to the SE of the sill.
- Full Text:
- Date Issued: 2002
- Authors: Ferré, Eric C , Bordarier, Cecile , Marsh, Julian S
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6733 , http://hdl.handle.net/10962/d1007543
- Description: The Insizwa sill, is a 25-km-diameter, >1000-m-thick layered mafic intrusion, part of the Karoo Igneous Province in South Africa. The peridotitic and gabbronoritic rocks are undeformed and mineral fabrics demonstrably result from magma flow. A horizontal, centimeter-scale model layering is visible in numerous outcrops. Plagioclase crystals are both tabular and elongated. Their preferred orientation, parallel to the layering, forms a foliation and a NW–SE lineation, respectively interpreted as the magma flow plane and flow direction. Throughout the 78 stations of this study (699 specimens), magnetic susceptibilities (K[subscript m]) range from 750 to 10,000×10[superscript (−6)] SI. The magnetic anisotropy (P[subscript j]) ranges from 1.03 to 1.08. Magnetic ellipsoids are both prolate and oblate (average T[subscript j]≈0). Anisotropy of magnetic susceptibility (AMS) fabrics are dominated by multidomain to pseudo-single domain magnetite. High-field magnetic experiments indicate that the paramagnetic contribution from the mafic silicates is less than 50 percentage for low susceptibility rock types. The anisotropy results from magnetite grain shape solely as shown by no significant increase in P[subscript j] with increasing K[subscript m]. The magnetic lineation (305°, 05°) is consistent throughout the sill at various scales and coincides with the mineral lineation in average. In contrast, the magnetic foliation (125° NE 10°) is generally perpendicular to the mineral foliation and to the layering. Several explanations for this odd configuration are discussed. The variations of magnetic parameters across the layering and field observations point to a multiple injection. The magnetic lineation is consistent with the presence of a single feeder dike situated to the SE of the sill.
- Full Text:
- Date Issued: 2002
Phylogenetics of advanced snakes (Caenophidia) based on four mitochondrial genes
- Kelly, Christopher M R, Barker, Nigel P, Villet, Martin H
- Authors: Kelly, Christopher M R , Barker, Nigel P , Villet, Martin H
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6960 , http://hdl.handle.net/10962/d1012005
- Description: Phylogenetic relationships among advanced snakes ( Acrochordus + Colubroidea = Caenophidia) and the position of the genus Acrochordus relative to colubroid taxa are contentious. These concerns were investigated by phylogenetic analysis of fragments from four mitochondrial genes representing 62 caenophidian genera and 5 noncaenophidian taxa. Four methods of phylogeny reconstruction were applied: matrix representation with parsimony (MRP) supertree consensus, maximum parsimony, maximum likelihood, and Bayesian analysis. Because of incomplete sampling, extensive missing data were inherent in this study. Analyses of individual genes retrieved roughly the same clades, but branching order varied greatly between gene trees, and nodal support was poor. Trees generated from combined data sets using maximum parsimony, maximum likelihood, and Bayesian analysis had medium to low nodal support but were largely congruent with each other and with MRP supertrees. Conclusions about caenophidian relationships were based on these combined analyses. The Xenoderminae, Viperidae, Pareatinae, Psammophiinae, Pseudoxyrophiinae, Homalopsinae, Natricinae, Xenodontinae, and Colubrinae (redefined) emerged as monophyletic, whereas Lamprophiinae, Atractaspididae, and Elapidae were not in one or more topologies. A clade comprising Acrochordus and Xenoderminae branched closest to the root, and when Acrochordus was assessed in relation to a colubroid subsample and all five noncaenophidians, it remained associated with the Colubroidea. Thus, Acrochordus + Xenoderminae appears to be the sister group to the Colubroidea, and Xenoderminae should be excluded from Colubroidea. Within Colubroidea, Viperidae was the most basal clade. Other relationships appearing in all final topologies were (1) a clade comprising Psammophiinae, Lamprophiinae, Atractaspididae, Pseudoxyrophiinae, and Elapidae, within which the latter four taxa formed a subclade, and (2) a clade comprising Colubrinae, Natricinae, and Xenodontinae, within which the latter two taxa formed a subclade. Pareatinae and Homalopsinae were the most unstable clades.
- Full Text:
- Date Issued: 2003
- Authors: Kelly, Christopher M R , Barker, Nigel P , Villet, Martin H
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6960 , http://hdl.handle.net/10962/d1012005
- Description: Phylogenetic relationships among advanced snakes ( Acrochordus + Colubroidea = Caenophidia) and the position of the genus Acrochordus relative to colubroid taxa are contentious. These concerns were investigated by phylogenetic analysis of fragments from four mitochondrial genes representing 62 caenophidian genera and 5 noncaenophidian taxa. Four methods of phylogeny reconstruction were applied: matrix representation with parsimony (MRP) supertree consensus, maximum parsimony, maximum likelihood, and Bayesian analysis. Because of incomplete sampling, extensive missing data were inherent in this study. Analyses of individual genes retrieved roughly the same clades, but branching order varied greatly between gene trees, and nodal support was poor. Trees generated from combined data sets using maximum parsimony, maximum likelihood, and Bayesian analysis had medium to low nodal support but were largely congruent with each other and with MRP supertrees. Conclusions about caenophidian relationships were based on these combined analyses. The Xenoderminae, Viperidae, Pareatinae, Psammophiinae, Pseudoxyrophiinae, Homalopsinae, Natricinae, Xenodontinae, and Colubrinae (redefined) emerged as monophyletic, whereas Lamprophiinae, Atractaspididae, and Elapidae were not in one or more topologies. A clade comprising Acrochordus and Xenoderminae branched closest to the root, and when Acrochordus was assessed in relation to a colubroid subsample and all five noncaenophidians, it remained associated with the Colubroidea. Thus, Acrochordus + Xenoderminae appears to be the sister group to the Colubroidea, and Xenoderminae should be excluded from Colubroidea. Within Colubroidea, Viperidae was the most basal clade. Other relationships appearing in all final topologies were (1) a clade comprising Psammophiinae, Lamprophiinae, Atractaspididae, Pseudoxyrophiinae, and Elapidae, within which the latter four taxa formed a subclade, and (2) a clade comprising Colubrinae, Natricinae, and Xenodontinae, within which the latter two taxa formed a subclade. Pareatinae and Homalopsinae were the most unstable clades.
- Full Text:
- Date Issued: 2003
Conceptualizing the human use of wild edible herbs for conservation in South African communal areas
- Dovie, Delali B K, Shackleton, Charlie M, Witkowski, Ed T F
- Authors: Dovie, Delali B K , Shackleton, Charlie M , Witkowski, Ed T F
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6626 , http://hdl.handle.net/10962/d1006818
- Description: The importance of wild edible herbaceous species to resource poor households in most rural economies within savannas has been little studied. This is because most of the herbs grow in impoverished species communities and lands, often referred to as ‘marginal lands’. The aim of this paper is to conceptualize how the economics of wild edible herbs to households can be used to add value to total livelihoods and conservation within traditional communal areas of South Africa. Analysis of the economics of the consumption of wild edible herbs in Thorndale (Bushbuckridge district) of the Limpopo province is presented. The majority of households consumed wild edible herbs, averaging 15.4 kg dried weight per household per year and valued at $167 per household. The herbs were mostly harvested from uncultivated areas of farms, and rangelands. There was little correlation between household characteristics and the dependence on wild herbs for food. The local people noted a decline in the availability of the species, although not much is known about attempts to cultivate them. The only reasons attributed to the decline were nutrient poor soils and insufficient rains. With this background, developing a local strategy to sustain the species through cultivation by households was found to be feasible. A multiple-use system for the herbs, their improvement and value addition towards commercialization and increased household usage may result in wider acceptance and subsequent cultivation. Species diversity will be enhanced whilst conserving the land on which they grow. This multiple use system may include species roles in soil and water conservation.
- Full Text:
- Date Issued: 2007
- Authors: Dovie, Delali B K , Shackleton, Charlie M , Witkowski, Ed T F
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6626 , http://hdl.handle.net/10962/d1006818
- Description: The importance of wild edible herbaceous species to resource poor households in most rural economies within savannas has been little studied. This is because most of the herbs grow in impoverished species communities and lands, often referred to as ‘marginal lands’. The aim of this paper is to conceptualize how the economics of wild edible herbs to households can be used to add value to total livelihoods and conservation within traditional communal areas of South Africa. Analysis of the economics of the consumption of wild edible herbs in Thorndale (Bushbuckridge district) of the Limpopo province is presented. The majority of households consumed wild edible herbs, averaging 15.4 kg dried weight per household per year and valued at $167 per household. The herbs were mostly harvested from uncultivated areas of farms, and rangelands. There was little correlation between household characteristics and the dependence on wild herbs for food. The local people noted a decline in the availability of the species, although not much is known about attempts to cultivate them. The only reasons attributed to the decline were nutrient poor soils and insufficient rains. With this background, developing a local strategy to sustain the species through cultivation by households was found to be feasible. A multiple-use system for the herbs, their improvement and value addition towards commercialization and increased household usage may result in wider acceptance and subsequent cultivation. Species diversity will be enhanced whilst conserving the land on which they grow. This multiple use system may include species roles in soil and water conservation.
- Full Text:
- Date Issued: 2007
Metus in the Roman law of obligations
- Authors: Glover, Graham B
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6336 , http://hdl.handle.net/10962/d1012401
- Description: [From the introduction]: An entire title of book four of Justinian’s Digest is devoted to explaining the doctrine of metus as it was understood at the time of the codification of the Roman law. That title begins with the following statement: "The praetor says: 'I will not hold valid what has been done under duress.'" This unequivocal statement of legal principle illustrates, in very general terms, that by the time the Corpus Iuris Civilis was compiled, the Romans disapproved of persons using threats to inspire the creation of legal obligations, and that it was possible to avoid the legal consequences of an obligation because it was induced by metus. The Corpus Iuris Civilis remains our most valuable source of authority with regard to how duress cases were treated in Roman times. But the relevant textual sources pose some fundamental difficulties. Far from containing a coherent, structured analysis of the law, the relevant passages in fact amount to a jigsaw-puzzle of uncoordinated, haphazard, and occasionally contradictory legal propositions
- Full Text:
- Date Issued: 2004
- Authors: Glover, Graham B
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6336 , http://hdl.handle.net/10962/d1012401
- Description: [From the introduction]: An entire title of book four of Justinian’s Digest is devoted to explaining the doctrine of metus as it was understood at the time of the codification of the Roman law. That title begins with the following statement: "The praetor says: 'I will not hold valid what has been done under duress.'" This unequivocal statement of legal principle illustrates, in very general terms, that by the time the Corpus Iuris Civilis was compiled, the Romans disapproved of persons using threats to inspire the creation of legal obligations, and that it was possible to avoid the legal consequences of an obligation because it was induced by metus. The Corpus Iuris Civilis remains our most valuable source of authority with regard to how duress cases were treated in Roman times. But the relevant textual sources pose some fundamental difficulties. Far from containing a coherent, structured analysis of the law, the relevant passages in fact amount to a jigsaw-puzzle of uncoordinated, haphazard, and occasionally contradictory legal propositions
- Full Text:
- Date Issued: 2004
Sailing between Scylla and Charybdis: Mayelane v Ngwenyama
- Authors: Kruuse, Helen
- Date: 2014
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54118 , vital:26392 , https://www.ajol.info/index.php/pelj/article/view/112096
- Description: Mayelane v Ngwenyama 2013 4 SA 415 (CC) is arguably the most important judgment concerning the recognition of customary marriages in recent times. This article attempts to unpack some of the many issues that arise from the case, namely: (a) the practical difficulties associated with ascertaining living customary law and the problems of identifying legal versus social norms; (b) the meaning of consent as a requirement of a customary marriage; (c) the implications of the case for equality between multiple wives in a customary marriage, and as between wives across customary marriages of different cultural traditions; and (e) the implications of the case for equality considerations more broadly. While the authors sympathise with the court in respect of the complex decision before it, it questions the Court's method and result, specifically for the equality rights of a second (or further) "wife" in a Vatsonga customary marriage. The authors suggest that the issues should be put to democratic deliberation by the legislative arm, rather than leaving courts in the unenviable position of having to decide these matters.
- Full Text:
- Date Issued: 2014
- Authors: Kruuse, Helen
- Date: 2014
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54118 , vital:26392 , https://www.ajol.info/index.php/pelj/article/view/112096
- Description: Mayelane v Ngwenyama 2013 4 SA 415 (CC) is arguably the most important judgment concerning the recognition of customary marriages in recent times. This article attempts to unpack some of the many issues that arise from the case, namely: (a) the practical difficulties associated with ascertaining living customary law and the problems of identifying legal versus social norms; (b) the meaning of consent as a requirement of a customary marriage; (c) the implications of the case for equality between multiple wives in a customary marriage, and as between wives across customary marriages of different cultural traditions; and (e) the implications of the case for equality considerations more broadly. While the authors sympathise with the court in respect of the complex decision before it, it questions the Court's method and result, specifically for the equality rights of a second (or further) "wife" in a Vatsonga customary marriage. The authors suggest that the issues should be put to democratic deliberation by the legislative arm, rather than leaving courts in the unenviable position of having to decide these matters.
- Full Text:
- Date Issued: 2014
Lesotho's general election of 1998 : rigged or de rigeur?
- Southall, Roger J, Fox, Roddy C
- Authors: Southall, Roger J , Fox, Roddy C
- Date: 1999
- Language: English
- Type: Article
- Identifier: vital:6726 , http://hdl.handle.net/10962/d1006808
- Description: The official result of Lesotho's general election of 1998, which saw a 79 out of 80 seat victory for the ruling Lesotho Congress of Democrats (LCD), was repudiated by the opposition, notably the former ruling Basotho National Party (BNP) and the Basutoland Congress Party (BCP). These latter parties were historic enemies but forged an alliance of convenience to contest the outcome of the election. By mobilising their supporters to occupy Maseru they successfully paralysed the capacity of the LCD to govern. After diplomatic preliminaries, this led to military intervention by South Africa and Botswana in September 1998 and their brokering of an agreement which restored the LCD to power, on the condition that a new election would be held within eighteen months, with the rules for that contest being discussed between the parties in the interim. That election has now been scheduled for April 2000. The article reviews the conduct and result of the general election of 1998. It concludes that the opposition's objections were largely spurious, but notes that the unbalanced nature of the LCD's victory – a product of the first-past-the-post electoral system – was a major cause of the wider crisis. It therefore proposes that any lasting settlement of political differences in Lesotho is going to require a new electoral system which will allow for a more inclusive outcome.
- Full Text:
- Date Issued: 1999
- Authors: Southall, Roger J , Fox, Roddy C
- Date: 1999
- Language: English
- Type: Article
- Identifier: vital:6726 , http://hdl.handle.net/10962/d1006808
- Description: The official result of Lesotho's general election of 1998, which saw a 79 out of 80 seat victory for the ruling Lesotho Congress of Democrats (LCD), was repudiated by the opposition, notably the former ruling Basotho National Party (BNP) and the Basutoland Congress Party (BCP). These latter parties were historic enemies but forged an alliance of convenience to contest the outcome of the election. By mobilising their supporters to occupy Maseru they successfully paralysed the capacity of the LCD to govern. After diplomatic preliminaries, this led to military intervention by South Africa and Botswana in September 1998 and their brokering of an agreement which restored the LCD to power, on the condition that a new election would be held within eighteen months, with the rules for that contest being discussed between the parties in the interim. That election has now been scheduled for April 2000. The article reviews the conduct and result of the general election of 1998. It concludes that the opposition's objections were largely spurious, but notes that the unbalanced nature of the LCD's victory – a product of the first-past-the-post electoral system – was a major cause of the wider crisis. It therefore proposes that any lasting settlement of political differences in Lesotho is going to require a new electoral system which will allow for a more inclusive outcome.
- Full Text:
- Date Issued: 1999
Men and talk about legal abortion in South Africa : equality, support and rights discourses undermining reproductive ‘choice’
- Macleod, Catriona I, Hansjee, Jateen
- Authors: Macleod, Catriona I , Hansjee, Jateen
- Date: 2013
- Language: English
- Type: Article
- Identifier: vital:6295 , http://hdl.handle.net/10962/d1014770 , http://www.tandfonline.com/doi/full/10.1080/13691058.2013.802815
- Description: Discursive constructions of abortion are embedded in the social and gendered power relations of a particular socio-historical space. As part of research on public discourses concerning abortion in South Africa where there has been a radical liberalisation of abortion legislation, we collected data from male group discussions about a vignette concerning abortion, and newspaper articles written by men about abortion. Our analysis revealed how discourses of equality, support and rights may be used by men to subtly undermine women's reproductive right to ‘choose’ an abortion. Within an Equal Partnership discourse, abortion, paired with the assumption of foetal personhood, was equated with violating an equal heterosexual partnership and a man's patriarchal duty to protect a child. A New Man discourse, which positions men as supportive of women, was paired with the assumption of men as rational and women as irrational in decision-making, to allow for the possibility of men dissuading women from terminating a pregnancy. A Rights discourse was invoked to suggest that abortion violates men's paternal rights.
- Full Text:
- Date Issued: 2013
- Authors: Macleod, Catriona I , Hansjee, Jateen
- Date: 2013
- Language: English
- Type: Article
- Identifier: vital:6295 , http://hdl.handle.net/10962/d1014770 , http://www.tandfonline.com/doi/full/10.1080/13691058.2013.802815
- Description: Discursive constructions of abortion are embedded in the social and gendered power relations of a particular socio-historical space. As part of research on public discourses concerning abortion in South Africa where there has been a radical liberalisation of abortion legislation, we collected data from male group discussions about a vignette concerning abortion, and newspaper articles written by men about abortion. Our analysis revealed how discourses of equality, support and rights may be used by men to subtly undermine women's reproductive right to ‘choose’ an abortion. Within an Equal Partnership discourse, abortion, paired with the assumption of foetal personhood, was equated with violating an equal heterosexual partnership and a man's patriarchal duty to protect a child. A New Man discourse, which positions men as supportive of women, was paired with the assumption of men as rational and women as irrational in decision-making, to allow for the possibility of men dissuading women from terminating a pregnancy. A Rights discourse was invoked to suggest that abortion violates men's paternal rights.
- Full Text:
- Date Issued: 2013
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