The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa

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dc.contributor.advisorErlank, A Jen_ZA
dc.contributor.authorMoore, Andrew Edwarden_ZA
dc.date.accessioned2015-03-13T14:06:03Z
dc.date.available2015-03-13T14:06:03Z
dc.date.issued1979en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractEarly Tertiary olivine melilitites and associated non-diamondiferous kimberlites occur in two pipe clusters in the Namaqualand and Bushmanland regions of South Africa. The more northerly cluster is centred about the town of Gamoep and the second is located south of Garies. The olivine melilitites are characterized by olivine phenocrysts which exhibit a broad range in composition on the scale of individual hand specimens. It is possible to distinguish four petrographically and chemically distinct olivine populations in both the northern and southern pipes studied: (a) Rare anhedral or subhedral olivines that display marked disequilibrium features with the surrounding matrix and which are characterized by having high iron and extremely low nickel contents (referred to as HILN olivines) relative to the remaining olivines in the same rock; (b) euhedral and often skeletal (hopper) olivines that are richer in Mg and Ni than HILN olivines in the same rock. Some of the euhedral olivines show abnormal zonation patterns ("unusual" hoppers). Hopper and HILN olivines contain fluid and carbonate inclusions which apparently record the separation of a vapour phase and an immiscible carbonate liquid during magma ascent: (c) large rounded olivines (megacrysts) up to 40 mm across. Individuals are chemically homogeneous, but megacrysts from the same pipe collectively define a trend of decreasing Mg with Ni (F092, 0.36% Ni to F075, 0.17% Ni). The most fayalitic megacrysts are depleted in Mg and Ni relative to the hopper olivines in the same rock. [d] In addition to these main populations, there also occur rare magnesium-rich (F091) anhedral olivines which show strained extinction and are believed to be xenocrysts.en_ZA
dc.identifier.apacitationMoore, A. E. (1979). <i>The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Geological Sciences. Retrieved from http://hdl.handle.net/11427/12595en_ZA
dc.identifier.chicagocitationMoore, Andrew Edward. <i>"The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 1979. http://hdl.handle.net/11427/12595en_ZA
dc.identifier.citationMoore, A. 1979. The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Moore, Andrew Edward AB - Early Tertiary olivine melilitites and associated non-diamondiferous kimberlites occur in two pipe clusters in the Namaqualand and Bushmanland regions of South Africa. The more northerly cluster is centred about the town of Gamoep and the second is located south of Garies. The olivine melilitites are characterized by olivine phenocrysts which exhibit a broad range in composition on the scale of individual hand specimens. It is possible to distinguish four petrographically and chemically distinct olivine populations in both the northern and southern pipes studied: (a) Rare anhedral or subhedral olivines that display marked disequilibrium features with the surrounding matrix and which are characterized by having high iron and extremely low nickel contents (referred to as HILN olivines) relative to the remaining olivines in the same rock; (b) euhedral and often skeletal (hopper) olivines that are richer in Mg and Ni than HILN olivines in the same rock. Some of the euhedral olivines show abnormal zonation patterns ("unusual" hoppers). Hopper and HILN olivines contain fluid and carbonate inclusions which apparently record the separation of a vapour phase and an immiscible carbonate liquid during magma ascent: (c) large rounded olivines (megacrysts) up to 40 mm across. Individuals are chemically homogeneous, but megacrysts from the same pipe collectively define a trend of decreasing Mg with Ni (F092, 0.36% Ni to F075, 0.17% Ni). The most fayalitic megacrysts are depleted in Mg and Ni relative to the hopper olivines in the same rock. [d] In addition to these main populations, there also occur rare magnesium-rich (F091) anhedral olivines which show strained extinction and are believed to be xenocrysts. DA - 1979 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1979 T1 - The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa TI - The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa UR - http://hdl.handle.net/11427/12595 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/12595
dc.identifier.vancouvercitationMoore AE. The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 1979 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/12595en_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.titleThe geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africaen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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