A genetic metasomatic link between eclogitic and peridotitic diamond inclusions

Sami Mikhail*, Michele Rinaldi, Eleanor R. Mare, Dimitri Sverjensky

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Diamond inclusions sample the otherwise inaccessible archive of Earth’s deep interior. The geochemical and petrological diversity of diamond inclusions reflects either pre-metasomatic upper mantle heterogeneity or metasomatism coeval with diamond formation. We focus on the origin of lithospheric garnet and clinopyroxene inclusions by simulating metasomatic reactions between eclogitic fluids and mantle peridotites at 5 GPa, 1000 °C, and across a range of redox conditions (logfO2 = −1 to −6 ΔFMQ). Our results demonstrate that fluid-rock interaction can result in the formation of eclogitic, websteritic, and peridotitic silicates from a single fluid during a single diamond-forming metasomatic event. Ergo, the petrogenesis of diamond and their inclusions can be syngenetic, and the petrological diversity of diamond inclusions can reflect metasomatism coeval with diamond formation. Furthermore, during the metasomatism, refractory peridotite can be converted to fertile websterite which could become a pyroxenitic mantle source for oceanic basalts.
Original languageEnglish
Pages (from-to)33-38
JournalGeochemical Perspectives Letters
Volume17
DOIs
Publication statusPublished - 24 Mar 2021

Keywords

  • Diamond formation
  • Metasomatism
  • Pyroxenite
  • Geochemical modelling
  • Mantle petrology
  • Deep carbon cycle

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