The role of natural solidification paths on REE partitioning between clinopyroxene and melt

P. Scarlato, S. Mollo*, J. D. Blundy, G. Iezzi, M. Tiepolo

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

17 Citations (Scopus)

Abstract

We document for the first time the role played by natural solidification paths on the partitioning of rare earth elements (REE) between clinopyroxene and melt. To do this, we investigated the compositional variation of clinopyroxenes formed under increasing cooling rate conditions from core to rim of a dike at Mt. Etna volcano. As the rate of cooling increases, clinopyroxenes are progressively depleted in Si + Ca + Mg counter-balanced by enrichments in Al + Na + Ti. Consequently, the concentration of REE in clinopyroxene increases due to an increased ease of locally balancing the excess charge at the M2 site as the number of surrounding tetrahedral aluminium atoms increases. Since Aliv in clinopyroxene is a charge-balancing cation for REE, the partition coefficients (DREE) measured at the dike chilled margin are distinctly higher than those from the dike interior. We conclude that, in naturally solidifying magmas, kinetically controlled cation substitution reactions can be treated in terms of the energetics of the various charge-imbalanced configurations. This finding is corroborated by the near-parabolic dependence of DREE on cation radius due to charge-balance mechanisms described by the lattice strain model.

Original languageEnglish
Pages (from-to)1-4
Number of pages4
JournalBulletin of Volcanology
Volume76
Issue number3
DOIs
Publication statusPublished - 1 Jan 2014

Keywords

  • Mt. Etna
  • Natural solidification path
  • Partition coefficient
  • REE

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