3. Electronic Theses and Dissertations (ETDs) - All submissions

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    Contributions to the geochronology and geological evolution of the Central African Copperbelt
    (2006-03-23) Rainaud, Christine Claire Laurence
    This thesis presents the results of a broad geochronological investigation into the nature and evolution of the Central African Copperbelt, host of world class Cu-Co deposits in Zambia and the Democratic Republic of Congo. UPb SHRIMP dating of detrital, xenocrystic and magmatic zircons and metamorphic monazite as well as 40Ar-39Ar analyses on biotite, muscovite and microcline constrained the nature and the evolution of the basement, the deposition of the Katangan sedimentary sequence and the provenance of the sediments, and finally the different metamorphic episodes which affected the region. Regarding the pre-Katangan basement, U-Pb SHRIMP analyses of detrital and xenocrystic zircons revealed the first evidence of a cryptic c. 3.2-3.0 Ga Mesoarchaean terrane, named the Likasi terrane, in the basement of the Copperbelt. It was also discovered that the Lufubu schists, previously thought to be sedimentary in origin, are in fact intermediate metavolcanic rocks. These Lufubu schists, together with granitoids and gneisses from Zambia, yielded U-Pb SHRIMP ages between 2050 Ma and 1850 Ma and are interpreted as being related to the evolution of a large magmatic arc (or several magmatic arcs). These Paleoproterozoic terrains define the Lufubu Metamorphic Complex, which evolved together with the Bangweulu Block, the Ubendian Belt and the Tanzanian craton to collide with the Angola-Kasai craton to form the Kibaran Belt during the 1.4-1.0 Ga Kibaran Orogeny. Unconformably overlying the Lufubu Metamorphic Complex is the Muva Group, which is sedimentary in origin. A maximum U-Pb age of 1941 ± 40 Ma was found for its deposition in the Copperbelt area. Concerning the Katanga Supergroup, U-Pb SHRIMP analyses on detrital zircons showed that the sediments are mainly derived by erosion from the Paleaoproterozoic basement. 40Ar-39Ar analyses of detrital muscovites from the Biano Group, which forms the topmost unit of the Katanga Supergroup, yielded a maximum age of deposition of 573 ± 5. This implies a terminal Neoproterozoic and/or early Palaeozoic age for terminal Katangan deposition, and supports previous models for the deposition of the Biano Group in a foreland basin to the Lufilian Orogen . Finally, U-Pb SHRIMP analyses on monazites and 40Ar-39Ar analyses on biotite, muscovite and K-feldspar yielded ages at c. 590, c. 530, c. 512 and a range between 492 and 450 Ma. These ages correspond respectively to various events during and following the Pan-African Damaran-Lufilian- Zambezi orogeny, formed by collision of the Congo and Kalahari cratons, namely to a tectonic event coinciding with subduction-related eclogite facies metamorphism elsewhere in the Lufilian orogen; to the final stage of collision between the Kalahari and Congo cratons; to a wide-spread regional mineralising event; and finally to post-orogenic uplift and regional cooling.
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    The transboundary transportation of pollutants from The Zambian Copperbelt
    (2006-02-10) Dlamini, Simangele
    The transportation of aerosols and trace gas material from industrial activities and biomass burning in southern Africa has received widespread attention from scientists over the past decade. Dominant circulation patterns in the sub-region facilitate the southward transportation of sulphur pollutants from the pyromerturllugical processing of copper in Zambia and the Democratic Republic of Congo (DRC), and products of biomass burning from countries in the sub-region in general. This research focuses on the contribution of industrial pollutants from the Zambian Copperbelt and products of biomass burning in the sub-region to total aerosol loading over South Africa. The seasonality of air transport over the region in general, and South Africa in particular, is determined from different transport fields and their frequency of occurrence. Data supplied by the European Center for Medium Range Weather Forecasting (ECMWF) has been used to run trajectories for the summer, autumn, winter and spring seasons for southern Africa for the years 1990-1994. Forward trajectories have been calculated for the 850, 800, 750 and 700hPa geopotential heights, from Kitwe (12.9° S, 28.2° E, 1262m above mean sea level), at 2.5° resolution. The wall programme has been used as a tool for analysis. Trajectories show widespread recirculation over the subcontinent, resulting in a net transportation of sulphate aerosols from the Zambian Copperbelt. Biomass burning products are likely to join this plume, especially during the late winter and spring seasons. During the summer, air transport is mainly to the west, via Angola and the Democratic Republic of Congo, off the eastern Atlantic towards southern America.
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