Kimberlites from source to surface

insights from experiments

Stephen F. Foley*, Gregory M. Yaxley, Bruce A. Kjarsgaard

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

High-pressure experiments are unconvincing in explaining kimberlites as direct melts of carbonated peridotite because the appropriate minerals do not coexist stably at the kimberlite liquidus. High-pressure melts of peridotite with CO2 and H2O have compositions similar to kimberlites only at pressures where conditions are insufficiently oxidizing to stabilize CO2: they do not replicate the high K2O/Na2O of kimberlites. Kimberlite melts may begin their ascent at ≈300 km depth in reduced conditions as melts rich in MgO and SiO2 and poor in Na2O. These melts interact with modified, oxidized zones at the base of cratons where they gain CO2, CaO, H2O, and K2O and lose SiO2. Decreasing CO2 solubility at low pressures facilitates the incorporation of xenocrystic olivine, resulting in kimberlites’ characteristically high MgO/CaO.

Original languageEnglish
Pages (from-to)393-398
Number of pages6
JournalElements
Volume15
Issue number6
DOIs
Publication statusPublished - 1 Dec 2019

Keywords

  • kimberlite
  • high-pressure experiments
  • volatiles
  • petrogenesis
  • CO₂

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