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Mg‐Fe partitioning between olivine and mafic‐ultramafic melts
Author(s) -
Kushiro Ikuo,
Walter Michael J.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/98gl01844
Subject(s) - olivine , mafic , natural bond orbital , ultramafic rock , peridotite , mantle (geology) , geology , mineralogy , partition coefficient , basalt , analytical chemistry (journal) , thermodynamics , geochemistry , chemistry , physics , computational chemistry , density functional theory , chromatography
The partitioning of Mg and Fe between olivine and mafic‐ultramafic melts has been examined based on previous and new experimental data. We find that the exchange partition coefficient, K D , changes primarily as a function of melt composition, expressed either as MgO+FeO content or degree of polymerization, NBO/T, rather than temperature or pressure. K D increases from about 0.23±0.02 at an NBO/T of ∼0 to a maximum of 0.35±0.02 at an NBO/T of ∼ 2, and then decreases to 0.23±0.02 for the pure olivine system (NBO/T=4). We suggest that the following empirical relation yields a reliable estimate of K D for mantle derived melts: K D = 0.235 + 0.120·(NBO/T) ‐ 0.031·(NBO/T)². The change of K D shown here should be taken into account when calculating the composition of olivine coexisting with basaltic to ultramafic melts.