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Browsing by Subject "Botswana Ghanzi Group"

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    Item type:Thesis, Access status: Restricted ,
    Mineralisation in the Neoproterozoic Ghanzi Group strata, the Boseto Exploration Area, NW Botswana and comparison with the Polish Kupferschiefer (Permian)
    (Data obrony: 2012-06-18) Letsholo, Maatla
    Wydział Geologii, Geofizyki i Ochrony Środowiska
    The Ghanzi Group metasedimentary succession in the southeastern part of the Damara orogenic belt in Botswana hosts strata-bound copper mineralisation at the redox boundary between the oxidized strata of the Ngwako Pan Formation and the reduced clastic strata of D’kar Formation. On the basis of sedimentary and stratigraphic investigations on selected borehole cores, microscopic observations, electron microscope analyses, stable isotope analyses, geochemistry of organic matter, the relationships between the host rock and mineralisation were investigated leading to the discovery of precious metals (PGEs) in the Boseto area. Microscopic observations revealed diverse mineral association related to sedimentary and tectonic structures enabling the reconstruction of a paragenetic sequence of the ore minerals. Copper sulphides appear to be the dominant minerals with minor Pb and Zn sulphides, molybdenite, emplectite and Pd-Hg tellurides. Platinum Group Minerals (PGMs) associated with emplectite and molybdenite were identified in a veinlet cross-cutting quartz and calcite vein. Similar veins were identified in other samples and they have a potential of hosting precious metals since they are mineralised with molybdenite as well. Two main types of mineralisation were noted: - (i) an older type related to the diagenetic stage and evidenced by the strata-bound chalcocite hosted by siltstone strata, and (ii) a younger type of fracture-related mineralisation associated with recurring hydrothermal fluid pulses evidenced by secondary chalcocite cross-cutting molybdenite in a veinlet. Similar to the Ghanzi Group mineralisation, the Kupferschifer deposit is related to the early diagenetic to tectonic stages.