Mineralogy and provenance of the TiO₂ - ilmenite heavy mineral sand deposit of Nataka

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dc.contributor.advisorHarris, Chrisen_ZA
dc.contributor.authorElias, Sílvio Joséen_ZA
dc.date.accessioned2017-01-31T09:11:12Z
dc.date.available2017-01-31T09:11:12Z
dc.date.issued2016en_ZA
dc.description.abstractThe Nataka heavy mineral sand deposit occurs along the northeast Mozambique coastline. It comprises a regional Pleistocene elliptical structure extending from Somalia, passing through Kenya, Tanzania, Madagascar and Mozambique, to Richards Bay in South Africa. The deposit consists of fine- to medium- grained, unconsolidated red sediments, hosting heavy minerals. The deposit mineral assemblage is made up of non-valuable phases comprising mostly magnetite, hematite, chromite, monazite, and the valuable phases dominated by ilmenite (50.91 wt. %), with additional zircon and rutile (9.96 and 3.52 wt. % respectively). The total heavy minerals comprise about 5% volume, of which 2 % are valuable heavy minerals making up about 445 Mt (million tonnes) probable resources. This study focuses on the mineralogical characterization of ilmenite from the Nataka deposit, alongside with sediment provenance. Mineralogical and chemical characterisation of ilmenite undertaken on 32 samples from 16 selected drill holes using a combination of QEMSCAN and EPMA revealed that the ilmenite has undergone different stages of alteration, at distinct environment conditions, yielding products spanning from hydrated ilmenite to leucoxene. The alteration dominantly involved groundwater, which was oxidizing and acidic, hence the predominance of ilmenite-pseudorutile alteration. Long exposure to direct sunshine has been hypothesized as a different process that might have favoured the direct alteration of ilmenite to leucoxene and of pseudorutile to leucoxene, on a smaller scale. The major impurities in the ilmenite are Al and Si, which are enriched in the advanced ilmenite alteration products (leucoxene), where they fill pores and cracks. Chromium impurities occur as discrete grains of chrome spinel. The compositional variety of magnetite, Cr-spinel, tourmaline, zircon and rutile indicate major contribution from granitoid terranes, subjected to granulite metamorphic facies (750 to 1000 :C), and minor contribution from mafic plutonic intrusions. The granitoid field as a sediment source area if analysed in conjunction with zircon ages (1100 – 900 Ma, 900 – 700 Ma, and 650 – 500 Ma), and zircon δ¹⁸O (7.07 ‰) is consistent with preferential sourcing from the proximal Mesoproterozoic Nampula Complex, with some contribution from igneous plutonic rocks from Xixano, Lalamo and Montepuez Complexes.en_ZA
dc.identifier.apacitationElias, S. J. (2016). <i>Mineralogy and provenance of the TiO₂ - ilmenite heavy mineral sand deposit of Nataka</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Geological Sciences. Retrieved from http://hdl.handle.net/11427/23762en_ZA
dc.identifier.chicagocitationElias, Sílvio José. <i>"Mineralogy and provenance of the TiO₂ - ilmenite heavy mineral sand deposit of Nataka."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2016. http://hdl.handle.net/11427/23762en_ZA
dc.identifier.citationElias, S. 2016. Mineralogy and provenance of the TiO₂ - ilmenite heavy mineral sand deposit of Nataka. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Elias, Sílvio José AB - The Nataka heavy mineral sand deposit occurs along the northeast Mozambique coastline. It comprises a regional Pleistocene elliptical structure extending from Somalia, passing through Kenya, Tanzania, Madagascar and Mozambique, to Richards Bay in South Africa. The deposit consists of fine- to medium- grained, unconsolidated red sediments, hosting heavy minerals. The deposit mineral assemblage is made up of non-valuable phases comprising mostly magnetite, hematite, chromite, monazite, and the valuable phases dominated by ilmenite (50.91 wt. %), with additional zircon and rutile (9.96 and 3.52 wt. % respectively). The total heavy minerals comprise about 5% volume, of which 2 % are valuable heavy minerals making up about 445 Mt (million tonnes) probable resources. This study focuses on the mineralogical characterization of ilmenite from the Nataka deposit, alongside with sediment provenance. Mineralogical and chemical characterisation of ilmenite undertaken on 32 samples from 16 selected drill holes using a combination of QEMSCAN and EPMA revealed that the ilmenite has undergone different stages of alteration, at distinct environment conditions, yielding products spanning from hydrated ilmenite to leucoxene. The alteration dominantly involved groundwater, which was oxidizing and acidic, hence the predominance of ilmenite-pseudorutile alteration. Long exposure to direct sunshine has been hypothesized as a different process that might have favoured the direct alteration of ilmenite to leucoxene and of pseudorutile to leucoxene, on a smaller scale. The major impurities in the ilmenite are Al and Si, which are enriched in the advanced ilmenite alteration products (leucoxene), where they fill pores and cracks. Chromium impurities occur as discrete grains of chrome spinel. The compositional variety of magnetite, Cr-spinel, tourmaline, zircon and rutile indicate major contribution from granitoid terranes, subjected to granulite metamorphic facies (750 to 1000 :C), and minor contribution from mafic plutonic intrusions. The granitoid field as a sediment source area if analysed in conjunction with zircon ages (1100 – 900 Ma, 900 – 700 Ma, and 650 – 500 Ma), and zircon δ¹⁸O (7.07 ‰) is consistent with preferential sourcing from the proximal Mesoproterozoic Nampula Complex, with some contribution from igneous plutonic rocks from Xixano, Lalamo and Montepuez Complexes. DA - 2016 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2016 T1 - Mineralogy and provenance of the TiO₂ - ilmenite heavy mineral sand deposit of Nataka TI - Mineralogy and provenance of the TiO₂ - ilmenite heavy mineral sand deposit of Nataka UR - http://hdl.handle.net/11427/23762 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/23762
dc.identifier.vancouvercitationElias SJ. Mineralogy and provenance of the TiO₂ - ilmenite heavy mineral sand deposit of Nataka. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2016 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/23762en_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.otherGeologyen_ZA
dc.titleMineralogy and provenance of the TiO₂ - ilmenite heavy mineral sand deposit of Natakaen_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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