About specific character and productivity of enriched by micas kimberlites

Abstract

      Carried out research and general conclusions of available material indicated, that the role of diamondiferous kimberlites decreases in the direction from the center of the Siberian platform and towards its northern territories. In the northern part of the platform alkaline picrites dominate, while in the central diamondiferous regions kimberlites formed in the range of the whole area of diamond stability. Among more than 30 diamondiferous regions of the Siberian platform some contain enriched by micas kimberlites, bright representatives of which are rocks of the Nakyn field diatremes (Botuobinskaya, Nyurbinskaya and body Maiskoye). The rocks of this field pipes belong to one petrochemical type of kimberlites, and the defined concentration variations of petrogenic oxides are related with different intensity of postmagmatic and hypergene processes’ occurrence at different depths of diatremes. Sufficient alteration of kimberlites, with broad development of serpentine, carbonates, phlogopite and products of its alteration – chlorite, take place during indicated stages of diatremes formation. Correlation analysis of minerals-neoformations’ distribution with potential diamondiferousness of kimberlites indicated inverse relationship of mica, quartz and dolomite grade with concentration of useful component. Prevalence of transparent (or semitransparent) diamonds of octahedral to rhombic dodecahedral habit of variety I is a typical feature of investigated micaceous kimberlites, at noticeable content of crystals with variety IV envelope (cover).