Geochemistry of Kimberlites

In the chapter on kimberlite petrography, it was stressed that kimberlite is a complex hybrid rock, composed of varying proportions of mantle or crustal xenoliths. Moreover, mode of emplacement and degree of interaction with groundwater are very variable from intrusion to intrusion. Since all these variables, together with the partial and variable degrees of melting within the upper mantle at the onset of kimberlite generation (and subsequent modifications en route to the surface), will be expessed in the bulk compositions of different kimberlites, it is very doubtful if any bulk-rock analysis will reflect pristine kimberlite composition.