Unfolding primary composition of kimberlite melt and processes of mantle enrichment in critical metals; their effect on economic value of kimberlites

Kimberlites, the deepest mantle magmas that reach the surface of the Earth, are the hosts to the major economic diamond deposits. Kimberlites originate deep (> 150 km) in subcontinental mantle due to poorly understood processes of chemical enrichment of the mantle with rare and volatile elements including some of the critical metals. This makes understanding of processes of kimberlite melt production in the mantle very important. The proposed project aims to establish the composition, origin and evolution of primary kimberlite melt and its effect on the eruption mechanism and kimberlite geology. The existing views on the composition of primary kimberlite melt vary between carbonatitic and silicate melt based on (i) study of bulk rock geochemistry and mineralogy of kimberlites and on (ii) experimental melting of possible mantle sources of kimberlites. The proposed project will integrate these studies with a novel method which examines the reaction between kimberlite magma and mantle minerals carried by kimberlites (diamond, chromite, ilmenite, garnet). In response to the crystallization conditions and composition of kimberlite magma, these minerals develop: (i) dissolution features, (ii) compositional zoning, and (iii) rims of secondary mineral phases. The proposed study will use high-pressure-experiments to examine these reactions and apply the results to natural diamonds and Fe-Ti oxides from worldwide kimberlite localities. Collaboration with diamond mining industry provides an exceptional access to the samples with geological control from specific depths and units within composite kimberlite pipes. Knowledge of the composition and evolution of kimberlite melt is essential for understanding: mantle processes leading to kimberlite magmatism, causes of the large variation in kimberlite geology, and their effect on diamond economic potential. The study aims to develop new analytical methods to help improving exploration techniques and assessment of kimberlite bodies, for sustaining and adding value to the existing mines. The proposed research will help to unravel deep mantle processes and improve exploration techniques to benefit diamond mining industry in Canada, the third world largest diamond producer.