Oxygen potential of diamond formation in the lower mantle

I. D. Ryabchikov, F. V. Kaminsky

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Thermodynamic calculations have shown that when a metallic phase arising due to ferroan ion disproportionation is contained in lower-mantle rocks, carbon occurs as iron carbide and the oxygen fugacity corresponds to the equilibrium of ferropericlase with Fe-Ni alloy. The typical values of oxygen fugacity in zones of diamond formation in the lower mantle lie between the iron-wüstite buffer and six logarithmic units above this level. The processes that proceed in the lower mantle give rise to variation of fO_2 within several orders of magnitude above the elevated fO_2 values, which are necessary for the formation of diamond, as compared with a common level typical of the lower mantle. The mechanisms responsible for redox differentiation in the lower mantle comprise the subduction of oxidized crustal material, mechanical separation of metallic phase and silicate-oxide mineral assemblage enriched in ferric ions, as well as transfer of fused silicate material presumably enriched in Fe3+ through the mantle.

Original languageEnglish
Pages (from-to)1-12
Number of pages12
JournalGeology of Ore Deposits
Volume55
Issue number1
DOIs
Publication statusPublished - 2013
Externally publishedYes

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