Digestion Fractional Crystallization (DFC): an important process in the henesis of kimberlites. Evidence from olivine in the Majuagaa kimberlite, southern West Greenland

L.H. Pilbeam, T.F.D. Nielsen, T.E. Waight

Research output: Contribution to journalArticleResearchpeer-review

84 Citations (Scopus)

Abstract

High-precision electron microprobe data for major and trace elements (nickel, calcium and manganese) in the margins and rims of groundmass olivine grains from the Majuagaa kimberlite (sensu stricto) in southernWest Greenland are presented. Despite a range of olivine core compositions defining several zoning types most of the olivine grains have similar margins. The olivine cores are considered to be xenocrysts in the kimberlite magma whereas the margins represent cognate olivine crystallized from the kimberlite melt itself.We evaluate models of olivine margin formation by fractional crystallization, fractional crystallization with simultaneous digestion of xenoliths, and diffusion. Only fractional crystallization coupled with digestion of xenocrysts (primarily orthopyroxene), with subsequent minor diffusion, can account for the observed compositional profiles in the olivine margins.We propose that the digestion crystallization process, whereby the entrained xenolithic material reacts with the kimberlite melt, is important in the evolution of kimberlite magmas.We suggest that this type of reaction gives a distinct local flavour to the parental kimberlite melt and can account for the similarities and differences between the various kimberlitic (sensu lato) magma types present in southern West Greenland and worldwide.

Original languageEnglish
Pages (from-to)1399-1425
Number of pages27
JournalJournal of Petrology
Volume54
Issue number7
DOIs
Publication statusPublished - Jul 2013

Keywords

  • Carbonatite
  • Crystallization
  • Kimberlite
  • Olivine
  • Orthopyroxene

Programme Area

  • Programme Area 4: Mineral Resources

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