ISOTOPIC COMPOSITON OF CARBON IN POLYCRYSTALLINE AGGREGATES OF DIAMOND WITH INCLUSONS OF GARNET AND RUTILE FROM THE MIR PIPE

Abstract

Polycrystalline aggregates of bort-type diamond with inclusions of garnet and rutile from the Mir pipe have delta C-13 of -3.7 to -22.9 parts per thousand PDB. The bort of variety VIII (Yu.L. Orlov's classification) differs from the bort of variety IX in having a narrower range of delta C-13 (-3.7 to -9.4 and -3.8 to -22.9 parts per thousand, respectively). The isotopically heavy diamond aggregates (delta C-13>similar to 10 parts per thousand) with cubic individuals make the maximum contribution of C-12 as compared with the aggregates having individuals of other morphological types. Within the Mir pipe, the E-type bort is statistically enriched in C-13 relative to single diamond crystals of the same paragenesis.