Criteria of the mantle metasomatism intensity and diamond grades of kimberliotes

We proposed an assessment of the intensity of metasomatic processes in mantle sampled by kimberlites on the example of samples of pyrope compositions from kimberlites with a known diamond grade. The intensity of metasomatic dissolution was estimated on the Ti correlations,  for low and high- Cr  pyropes.

For the titanium content in the pyrope compositions, positive high correlation coefficients were determined for such elements as  Hf, Zr, .Na  typical for the processes of alkaline H₂O metasomatism. Binary diagrams makes it possible to determine the main relationship between the mineral-forming elements in the compositions of pyropes and its mineral impurities. Weconcluded that this metasomatism leads to the dissolution of low-chromic pyropes but diamonds still remain and may continue to grow. A higher degree of metasomatism the pyropes are characterized by a high content of titanium,  for pyropes with high chromium contents. High degree of metasomatosis, brings to dissolution of pyropes and diamonds.

Burren  kimberlite pipe Dennis, Pobeda, and Zarnotsa  contains more than 14 %  pyrope grains ad diamond affinity according to  to N. V. Sobolev . Dennis ans dimond bearing thhe Pobeda is burren and Zarnitsa ~0.3 crt/t 

It is considered [1-5] that if the sample contains grains from diamond-bearing eclogical parageneses, or creased percentage of grains from diamond-bearing parageneses according to N. V. Sobolev [1],should contain diamonds.  But  for pyropes containing chromium oxides, Cr pyropes with TIO₂ > 0.6 weight  %, should be burren.  As well  even if  there is  high grain content o from th cluster group G10 according to the classification Dawson J. B., Stephens W. E. [2] . Grant RFBR 19-05-00788.

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