The Nature of Kimberlite Source Regions: A Hf-Nd Isotopic Study of Slave Craton Kimberlites

field into that of transitional kimberlites, with eNd(T) values as low as -3 and eSr(T) values of up to +22. The five samples for which Nd-Hf isotope data are available also span the range from Kaapvaal GPI to transitional. Four samples plot well within the “mantle array” while one (HL-12) plots significantly below, with a ∆eHf of -9.9. This sample has very similar Sr-Nd-Hf isotopic characteristics to the South African transitional Melton Wold kimberlite and is our first convincing indication of a component with negative DeHf contributing to the source of Slave kimberlites. Discussion These analyses of Canadian kimberlites indicate that they plot within error of the fields defined by GPI and transitional kimberlites of the Kaapvaal craton in both Hf-Nd and Nd-Sr space, and so could potentially be subject to the same petrogenetic interpretations, [1-2]. Our results show that kimberlites with Hf-Nd isotope compositions plotting significantly below the mantle array occur in both the Kaapvaal and Slave cratons; these signatures have also been recorded from the Siberian, Kimberley and Wyoming cratons [2]. This result is consistent both with models involving kimberlite genesis from a globally extensive ultra-deep reservoir such as the core-mantle boundary, and models invoking inheritance of the negative ∆eHf signature in the sub-continental lithosphere.