Primary uranium mineralisation of the central Damara Orogen, Namibia

A thesis submitted to the Faculty of Science in fulfilment of the requirements for the degree of Doctor of Philosophy at the School of Geosciences University of the Witwatersrand, Johannesburg, 2017Namibia, the 6th largest producer of uranium globally, has produced uranium from Pan African granite-hosted (primary) deposits since 1976, and from palaeochannel deposits since 2007; exporting 3 472 tonnes U in 2016. The large granite-hosted deposits at the Husab Mine are expected to add over 5 700 tonnes U/year at peak, while three large primary-hosted deposits remain in various stages of development at Goanikontes, the Ida Dome, and Valencia. This study presents a comprehensive geological, geochemical and uranium mineralogical appraisal of four of the major primary-hosted uranium deposits, all situated within the southern Central Zone (sCZ) of the polydeformational (D1-D3) Damara Belt. The sCZ comprises highly deformed Neoproterozoic sediments, unconformably draped over rheologically competent granite-gneiss domes and inliers of a Palaeoproterozoic basement. A suite of fractionated sheeted leucogranites (SLGs) are a characteristic of the final stages of Orogenic deformation; while most SLGs appear to precede D3 deformation and metamorphism (ca. 510 Ma); most of the mineralised SLGs across the region invade reduced-facies sediments in pressure shadows formed in the hinges and limbs of upright D3 antiforms, proximal to basement inliers. A pre-existing, six-fold, alphabetised SLG classification scheme is revised and extended to categorise distinctive and consistent field and petrographic characteristics of the SLGs across the region. Discriminating SLG sub-types is less consistent in standard geochemical diagrams, except where high field-strength (HFS) and rare-earth elements (REE) are concerned. REE profiles in pre-D3 SLGs reflect abundances, or paucities, of characteristic accessory mineral assemblages; while REE profiles show relative REE enrichment, prominent REEfractionation and -ve Eu anomalies in the uraniferous SLGs, reflecting lower-percentage partial melts in the more uraniferous samples. The overwhelming majority of primary uranium mineralisation is in magmatic uraninite, followed by coffinite which predominate as a replacement phase of uraninite, and more rarely as solid solution with thorite. The refractory minerals betafite and brannerite are rare, but are locally abundant in discrete, magmatic textures within uraniferous SLGs of some deposits. Hydrated uranyl silicates predominate in the supergene portions of the orebodies across the region. An electron microprobe study presents the first comprehensive assessment of uraninite compositions in the region, while Husab deposit betafite and brannerite compositions allow for a well-rounded comparison with refractory minerals from the Rössing deposits. Key Words Primary Uranium, Granite, Orogenic, Damara, Namibia, Rare Earth Elements, Mineralisation, Fractionation, High-grade Metamorphism, Economic Geology, Mining, Processing, Uraninite, Coffinite, Etango, Goanikontes, Husab, Ida Dome, Rössing, ValenciaXL201

Biodiversity of Angola

This open access multi-authored book presents a 'state of the science' synthesis of knowledge on the biodiversity of Angola, based on sources in peer-reviewed journals, in books and where appropriate, unpublished official reports. The book identifies Angola as one of the most biologically diverse countries in Africa, but notes that its fauna, flora, habitats and the processes that drive the dynamics of its ecosystems are still very poorly researched and documented. This 'state of the science' synthesis is for the use of all students of Angola's biodiversity, and for those responsible for the planning, development and sustainable management of the country's living resources. The volume brings together the results of expeditions and research undertaken in Angola since the late eighteenth century, with emphasis on work conducted in the four decades since Angola's independence in 1975. The individual chapters have been written by leaders in their fields, and reviewed by peers familiar with the region

Biodiversity of Angola

This open access multi-authored book presents a 'state of the science' synthesis of knowledge on the biodiversity of Angola, based on sources in peer-reviewed journals, in books and where appropriate, unpublished official reports. The book identifies Angola as one of the most biologically diverse countries in Africa, but notes that its fauna, flora, habitats and the processes that drive the dynamics of its ecosystems are still very poorly researched and documented. This 'state of the science' synthesis is for the use of all students of Angola's biodiversity, and for those responsible for the planning, development and sustainable management of the country's living resources. The volume brings together the results of expeditions and research undertaken in Angola since the late eighteenth century, with emphasis on work conducted in the four decades since Angola's independence in 1975. The individual chapters have been written by leaders in their fields, and reviewed by peers familiar with the region

Mapping of Welwitschia Mirabilis with high resolution satellite imagery in the Namib Desert

This study is about a non-invasive mapping technique of Welwitschia mirabilis in its habitat, the Namib-Naukluft Park, based on spatially high resolved satellite images. First, two satellite data sets from IKONOS and Quickbird satelliteare geometrically corrected, including GPS ground control points and a digital elevation model. Second, Welwitschia individuals, bushes, sandy and rocky surroundings are successfully mapped with a supervised and object-oriented classification approach. GPS points, training samples and verification objects have been collected previously in a field survey. 49 of 55 (89%) Welwitschia individuals known in ground reference, were classified successfully in both data sets, despite the limited spectral and spatial resolution. Compared to a pixel-based classification of Welwitschia with IKONOS data also published on this conference, it was shown, that the object-oriented approach improves the mapping precision of Welwitschia species. The presented area wide mapping technique from space is effective and non-invasive, but limited by the spatial and spectral resolution of the input satellite data

Population-Development-Environment in Namibia. Background Readings

The papers in this compendium represent a preparatory stage in the creation of a population-development-environment model for Namibia. As will be explained in the following section, this model requires information beyond lists of statistics. It is necessary to understand the reasons for the current state of affairs so that the scenarios made by the model are understood within a broader context. Also important is an understanding of the policy framework which will govern the activities of each sector. Legislation, policies and practical programs need to be understood so they too can be appropriately considered in the model. It is with these aims in mind that the respective authors were asked to contribute their knowledge of Namibia to this project. As the model began to coalesce, it became clear that the background papers themselves deserved more than just a supplementary role. Together they present a reasonable body of information about different aspects of Namibian society. Given that the literature on Namibia is sparse and often contained in unpublished reports, these papers, many of which draw their information from this hidden or 'gray literature,' deserve to see the light of day in the form of this collection. In the pages that follow, a brief description of the PDE model and its components is presented, after which, the focus will shift to specific issues which relate to Namibia