Thermal and compositional structure of the Superior Craton, Canada: Lithospheric architecture and implications for diamond prospectivity

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Mineral resources exploration through geophysics is usually associated with shallow subsurface imaging to find ore deposits. However, we can also learn a great deal by studying the deep, large-scale structure of the continents to find out more about how the minerals are created at depth and how they find their way to the surface. This "mineral systems" approach is gaining popularity in Canada, paving the way for a new generation of studies of deep structure. De Beers Canada has been actively exploring for diamonds in Canada since the 1960s and has operated 3 diamond mines in Ontario and the Northwest Territories. Diamonds are initially formed at great depth, under specific conditions of temperature and pressure, and are brought to the surface by volcanic eruptions that penetrate through the deep continental "root". The distribution of diamondiferous deposits is therefore controlled by both the deep structure of the continent and by the "pathways" created from depth to surface by later volcanic activity. In order to improve exploration targeting for the diamond industry, we need to apply new methods that image the deep structure of the continent in 3D, in particular, variations in the temperature and chemical composition of the rocks. We will combine a diverse range of data, using both geophysics and geochemistry, to model the structure of the crust and upper mantle beneath central-eastern Canada, where some of the world's oldest rocks are found, and where the ancient continental "root" is known to be thick enough to support diamond formation. De Beers Canada will subsequently use the model to evaluate potential exploration targets across the region, where they can apply field-based survey methods to study the target areas in more detail, using field-based exploration projects. The aim of this Alliance partnership project is therefore to aid the discovery of new economically-important diamond prospects in the eastern Canadian Shield.