Journal article

Crystallisation sequence and magma evolution of the De Beers dyke (Kimberley, South Africa)

Ashton Soltys, Andrea Giuliani, David Phillips



We present petrographic and mineral chemical data for a suite of samples derived from the De Beers dyke, a contemporaneous, composite intrusion bordering the De Beers pipe (Kimberley, South Africa). Petrographic features and mineral compositions indicate the following stages in the evolution of this dyke: (1) production of antecrystic material by kimberlite-related metasomatism in the mantle (i.e., high Cr-Ti phlogopite); (2) entrainment of wall-rock material during ascent through the lithospheric mantle, including antecrysts; (3) early magmatic crystallisation of olivine (internal zones and subsequently rims), Cr-rich spinel, rutile, and magnesian ilmenite, probably on ascent to the surface..

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Awarded by Australian Research Council through a Discovery Early Career Research Award (DECRA)

Funding Acknowledgements

We thank Graham Hutchison for assistance with SEM and EPMA analysis at the University of Melbourne, and Karsten Goemann for help with FE-SEM and EPMA analysis at the University of Tasmania. We are grateful to the John J. Gurney Upper Mantle Room Collection (University of Cape Town) and the De Beers Group for providing the studied samples. Reviews by Matt Gaudet and an anonymous reviewer improved the manuscript. We thank Bruce Kjarsgaard for his thorough review, and efficient editorial handling. Andrea Giuliani acknowledges funding from the Australian Research Council through a Discovery Early Career Research Award (DECRA, grant n. DE-150100009). This is publication 33 from the Kimberlites and Diamonds Research Group at the University of Melbourne, also listed as contribution 1165 from the ARC Centre of Excellence for Core to Crust Fluid Systems and 1128 from the GEMOC Key Centre.