THE SIGNIFICANCE OF THE INTER-ELEMENT RELATIONSHIPS OF SOME MINOR AND TRACE ELEMENTS IN SOUTH AFRICAN KIMBERLITES

ABSTRACT Fifty-eight kimberlite samples from three localities: Premier, Koffyfontein–Ebenhaezer and Bellsbank, have been analysed for Ti, Nb, Ta, Zr, Hf, Sc, Cr, P and Y by modern instrumental techniques (XRF and INAA). From a comparison of the data obtained with that of crustal rocks, it is concluded that these elements are not grossly affected by crustal contamination. Abundance data are similar to data avilable for kimberlites from other localities. The micaceous kimberlites are characterized by higher concentrations of Nb, Ta, Zr, Hf, Sc and P (in addition to Sr, REE, Th and U) when compared with non micaceous kimberlites. The large range in concentration of elements such as Nb, Ta and P in the Bellsbank kimberlites cannot be accounted for by dilution with crustal carbonate. The formation of stable complexes in the presence of ions like OH − , COf 2- 3 and F − is considered to be a possible explanation for these high concentrations. The concentration of incompatible elements in kimberlite can only in part be accounted for by phlogopite in the source rock, and the presence of other minor phases such as apatite and rutile are suggested by the interelement relationships found.