The original objectives of this project were: 1) To understand the processes responsible for transporting, concentrating and fixing copper and other ore constituents during sedimentary basin evolution 2) To document the various stages and...
The original objectives of this project were: 1) To understand the processes responsible for transporting, concentrating and fixing copper and other ore constituents during sedimentary basin evolution 2) To document the various stages and paragenesis of copper deposition and remobilisation during basin evolution 3) To develop a range of geological, geochemical and isotopic vectors that point toward ore, both on a district and a deposit scale 4) To determine what is different about the setting and geological evolution of the African Copperbelt, compared to Australian Proterozoic sedimentary basins, that may explain the difference in copper (and cobalt) endowment in these areas 5) To apply research results from both Africa and Australia to produce better empirical exploration models for Proterozoic sediment-hosted copper deposits. Later, these were extended to include a review of copper metallogeny and geological evolution of the Paterson Province in Western Australia. Three years of research work have provided important insights in a number of areas that address these objectives. In Zambia, for instance, we now recognise the importance of structural controls for sedimentation in the Lower Roan: we have a more robust stratigraphy up to the lower Kundelungu, and we recognise broad-scale basin architecture of the Zambian Copperbelt area. Evaporites, and evaporite-related breccias are, or were, an important component of Upper Roan rocks. We can recognise regional alteration (potassic and sodic) and its relationship to mineralisation, and have developed at least one vectoring tool (carbon isotopes) to mineralisation. Lastly, the availability of reductants (which may take several forms) is recognised as a critical control on the localisation of Cu mineralisation. In South Australia, we recognise that copper deposits related to the Tapley Hill Formation share the same oxidised fluid/reducing trap site process with the Zambian Copperbelt deposits, but they occur at a different tectono-stratigraphic position, lack the intense alkali alteration and don't have the isotopically very light carbonate carbon seen in the Zambian deposits. More focussed work in the Willouran Trough has revealed that the stratigraphic equivalent of the Lower Roan rocks may be present, but they are not intact. Also we see the effects of catastrophic salt withdrawal during, or soon after, the Sturtian glaciation, in regional-scale collapse of Callana and Burra Group rocks. Our review of the Paterson Orogen in Western Australia suggests a fundamentally different style, and relative timing, for its copper mineralisation compared to the Zambian Copperbelt.
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