Diamond resorption in kimberlite and the mantle

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The majority of gem diamonds are mined from kimberlites - the deeply formed volcanic rocks, which carry diamonds from their growth region in the Earth's mantle to the surface. The diamond quality and grade can vary considerably even in neighboring kimberlite pipes. During residence in the mantle and ascent in kimberlite magma, diamond undergo partial dissolution and develop resorption features, which are sensitive to the conditions of the surrounding media. The existing diamond exploration methods use chemical composition of mantle-derived minerals to confirm their origin in the diamondiferous parts of the mantle. However, the surface morphology of diamond and other mantle minerals contain a wealth of unexplored information about the conditions of diamond residence as well as preservation potential in the mantle and in the kimberlite magma. This project will study diamond samples from several Canadian and Botswana kimberlite localities with known position within a kimberlite pipe. Surface features on natural diamonds will be compared to the products of diamond dissolution experiments at controlled conditions. The study uses an innovative method of quantitative characterization of diamond dissolution features with an Atomic Force Microscopy. The obtained data will allow us to explore a number of minerals such as chromite, ilmenite, apatite as an indicators of kimberlitic fluid and their potential use in diamond exploration for predicting fluid regime and diamond preservation in kimberlite magma. Combining state-of-the-art scientific imaging and experimental methods with the expertise of DeBeers geologists will provide unique outcomes for the understanding of fundamentals of kimberlite magmatism and refining the exploration methods. The project will examine the nature of mantle metasomatism recorded by the diamond crystals, determine the presence and composition of magmatic fluid during the kimberlite ascent, the effect of this fluid on the features of diamond population, and its role in kimberlite emplacement. Canada has emerged as the third largest diamond producer. The study will provide low cost analytical methods for assessment of diamond preservation during kimberlite emplacement.