Typomorphic Characteristics of Diamond Crystals with Olivine Inclusions from the Ebelyakh Placer and Kimberlite Bodies of Yakutian Diamondiferous Province

Ugap’eva S.S., Pavlushin A.D., Goryainov S.V.

 

The results of study of morphology features, type of structural orientation and calculation of residual pressure by Raman spectroscopy in olivine inclusions in diamonds from the Ebelyakh placer and kimberlite pipes of the Yakutian diamondiferous province are provided in order to identify syngenetic signs, physical parameters of their intrusion into diamonds from deposits of different genetic types. The studied diamonds with olivine inclusions are presented by crystals of the I variety on mineralogical classification of Yu.L. Orlov. The morphology of the olivine inclusions both in the kimberlite diamonds and in the diamonds from the Ebelyakh placer shows that olivine form depends on their arrangement in a volume of a host crystal. Epitaxial orientation of olivine inclusions in diamonds from kimberlites and non- epitaxial orientation in crystals from the Ebelyakh placer are observed by X-Ray method. The residual pressure value Pf =4,7±0,5 GPa corresponding to crystallization conditions at a model temperature of diamond growth 1200°С is calculated by Raman spectroscopy. According to these values the depth of diamond crystallization for the Aikhal and the Udachnaya pipes is not less than 165 km. The syngenetic signs for olivine inclusions from kimberlites are the epitaxial structural orientation in host crystal and features of their morphology. For olivine inclusions in diamonds from the Ebelyakh placer only one syngenetic sign is established.

 

Key words: diamond, inclusions, kimberlite, morphology, olivine, Raman spectroscopy, X-Ray, Yakutian diamondiferous province.

Science and Education, 2015, No.2, pp.28-34