Raman spectroscopy of inclusions in diamonds of Zapolyarnaya pipe (Yakutia)

Abstract

Introduction: inclusions in diamond from the Zapolyarnaya pipe of the Yakutsk diamondiferous kimberlite province have been studied. The aim of the work is to obtain new data on mineral inclusions, which will allow us to supplement information on the physico-chemical conditions of diamond crystallization, both from this deposit and the deep shells of the Earth as a whole.

Samples and research methods: a diamond crystal with an association of more than twenty different inclusions from the Zapolyarnaya kimberlite pipe (Yakutsk diamondiferous kimberlite province) was selected for study. Eight undiscovered inclusions were identified using Raman spectroscopy. Results and discussion. The following mineral phases have been identified: garnets, clinopyroxenes, rutile, wollastonite and carbonates. Garnets are represented by mineral varieties of the pyrope-almandine-grossular series; according to calculated data, pyrope minale prevails in the studied garnets (up to 0.47). Clinopyroxenes were determined within the range of diopside-omphacite series with an estimated magnesium number ~0.45 and ~0.37. The obtained magnesium number values refer pyroxenes to peridotite and eclogite paragenesis.

Conclusion: carbonates were found as monomineral inclusions (magnesite) and in associations: calcite and wollastonite, calcite and сlinopyroxene. The detection of carbonate phases in primary inclusions indicates their participation in the composition of the parent diamond-forming medium in the formation of diamonds and syngenetic phases. The attribution of the identified inclusions to peridotite and eclogite parageneses indicates a complex multi-stage history of diamond crystal growth and confirms the validity of the ultrabasic-basic evolution of the parent mantle substance.