Co-existing fluid and silicate inclusions in mantle diamond

E. L. Tomlinson*, A. P. Jones, J. W. Harris

*Corresponding author for this work

Research output: Contribution to journalArticle

103 Citations (Scopus)

Abstract

We document the compositions of co-existing silicate macro-inclusions and fluid micro-inclusions in the fibrous coats of eight coated diamonds from the Panda kimberlite (Canada). The mineral inclusions in the diamond coats come from either the peridotite suite (Cr-pyrope, orthopyroxene, olivine and Cr-diopside) or the eclogite suite (omphacite). Therefore, fibrous diamonds grow in the same paragenetic environments as octahedral diamonds. The inclusions document a more fertile source composition (lower Mg# and higher CaO) than for equivalent phases in octahedral diamonds from Panda and worldwide. However, moderate to high Cr2O3 contents in garnet and clinopyroxene inclusions suggest that this apparent fertility is due to a secondary process. Geothermometry of the silicate inclusions yields low equilibration temperatures of 930 to 1010 °C. The co-existing fluid micro-inclusions are dominated by H2O, carbonate and KCl. Fluid inclusions in both the peridotitic and eclogitic samples fall along linear arrays between Fe-Ca-Mg carbonate and KCl. Inclusions in the one eclogitic sample also contain quartz. We suggest that the diamonds have trapped both metasomatised minerals and the metasomatic fluid, and so provide a snap shot of a metasomatic event in the mantle.

Original languageEnglish
Pages (from-to)581-595
Number of pages15
JournalEarth and Planetary Science Letters
Volume250
Issue number3-4
DOIs
Publication statusPublished - 30 Oct 2006
Externally publishedYes

Keywords

  • coated diamond
  • fluid inclusions
  • metasomatism
  • silicate inclusions

Fingerprint Dive into the research topics of 'Co-existing fluid and silicate inclusions in mantle diamond'. Together they form a unique fingerprint.

  • Cite this