The geochemistry of the Karoo igneous volcanic and intrusive rocks of Botswana

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dc.contributor.authorWigley, Rochelle Anneen_ZA
dc.date.accessioned2016-08-18T13:53:00Z
dc.date.available2016-08-18T13:53:00Z
dc.date.issued1995en_ZA
dc.descriptionBibliography: pages 183-191.en_ZA
dc.description.abstractThe Mesozoic basalts and dolerites of Botswana underlie an estimated area of 150 000km2 and form part of the Karoo Igneous Province of southern Africa. The distribution of Karoo basalts in Botswana is limited essentially to three main sub-basins, the Central Kalahari Subbasin, northern Botswana and the Tuli Syncline and a major dyke swarm, with a WNW strike, extends across Botswana from the Namibian to Zimbabwean borders. This dissertation is a reconnaissance study which concentrates on the recognition and definition of distinct geocheinical sub-groups within the Karoo volcanic and intrusive rocks of · Botswana. 128 new whole rock samples were analyzed for major and trace element concentrations, in addition to the 70 whole rock analyses from Botswana which were available in the UCT database.· Mineral analyses and rare earth element compositions for selected samples are also presented. The basalts and dolerites of Botswana are assigned to one of the three geochemical lineages, i.e. the low-K20, the high-K20 and the felsite lineages on the basis of Si02, MgO and K20 concentrations. A number of distinct geochemical sub-groups· are recognised within these lineages according to whole rock compositions, normative mineralogy, petrography and outcrop character. The low-K20 lineage is subdivided into two main sub-groups on the basis of the Ti02 and Zr concentrations, i.e. the LTZ- and HTZ-type basalt and dolerite sub-groups. The LTZtype basalt sub-group (with ~2% Ti02 and ~250ppm Zr) represents the bulk of the Botswana dataset where the LTZ basalts of Botswana are shown to be lateral equivalents to the Lesotho Formation basalts of the Central Karoo area, considerably expanding the known outcrop area of this basalt type. Two dolerites are the only samples of intrusive equivalents of this voluminous LTZ basalt type in Botswana.,en_ZA
dc.identifier.apacitationWigley, R. A. (1995). <i>The geochemistry of the Karoo igneous volcanic and intrusive rocks of Botswana</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Geological Sciences. Retrieved from http://hdl.handle.net/11427/21335en_ZA
dc.identifier.chicagocitationWigley, Rochelle Anne. <i>"The geochemistry of the Karoo igneous volcanic and intrusive rocks of Botswana."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 1995. http://hdl.handle.net/11427/21335en_ZA
dc.identifier.citationWigley, R. 1995. The geochemistry of the Karoo igneous volcanic and intrusive rocks of Botswana. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Wigley, Rochelle Anne AB - The Mesozoic basalts and dolerites of Botswana underlie an estimated area of 150 000km2 and form part of the Karoo Igneous Province of southern Africa. The distribution of Karoo basalts in Botswana is limited essentially to three main sub-basins, the Central Kalahari Subbasin, northern Botswana and the Tuli Syncline and a major dyke swarm, with a WNW strike, extends across Botswana from the Namibian to Zimbabwean borders. This dissertation is a reconnaissance study which concentrates on the recognition and definition of distinct geocheinical sub-groups within the Karoo volcanic and intrusive rocks of · Botswana. 128 new whole rock samples were analyzed for major and trace element concentrations, in addition to the 70 whole rock analyses from Botswana which were available in the UCT database.· Mineral analyses and rare earth element compositions for selected samples are also presented. The basalts and dolerites of Botswana are assigned to one of the three geochemical lineages, i.e. the low-K20, the high-K20 and the felsite lineages on the basis of Si02, MgO and K20 concentrations. A number of distinct geochemical sub-groups· are recognised within these lineages according to whole rock compositions, normative mineralogy, petrography and outcrop character. The low-K20 lineage is subdivided into two main sub-groups on the basis of the Ti02 and Zr concentrations, i.e. the LTZ- and HTZ-type basalt and dolerite sub-groups. The LTZtype basalt sub-group (with ~2% Ti02 and ~250ppm Zr) represents the bulk of the Botswana dataset where the LTZ basalts of Botswana are shown to be lateral equivalents to the Lesotho Formation basalts of the Central Karoo area, considerably expanding the known outcrop area of this basalt type. Two dolerites are the only samples of intrusive equivalents of this voluminous LTZ basalt type in Botswana., DA - 1995 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1995 T1 - The geochemistry of the Karoo igneous volcanic and intrusive rocks of Botswana TI - The geochemistry of the Karoo igneous volcanic and intrusive rocks of Botswana UR - http://hdl.handle.net/11427/21335 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/21335
dc.identifier.vancouvercitationWigley RA. The geochemistry of the Karoo igneous volcanic and intrusive rocks of Botswana. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 1995 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/21335en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Geological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherGeological Sciencesen_ZA
dc.titleThe geochemistry of the Karoo igneous volcanic and intrusive rocks of Botswanaen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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