Primary melting sequence of a deep (>Â 250Â km) lithospheric mantle as recorded in the geochemistry of kimberlite-carbonatite assemblages, Snap Lake dyke system, Canada

Modeling of partial melting requires that the source for Snap Lake dyke rocks was enriched in incompatible elements but depleted in HREE relative to the primitive mantle. The most appropriate source rocks are metasomatically enriched peridotites of the deep lithospheric mantle roots. In the melting sequence of this source, the incipient magma was carbonatitic in composition but subsequently became kimberlitic as the degree of partial melting increased to 1%. Rocks of the Snap Lake dyke represent a natural example of primary melting process within a deep (> 250 km) lithospheric mantle.