Experimental determination of Fe and Mg exchange between garnet and olivine and estimation of Fe-Mg mixing properties in garnet

R. T. Hackler, B. J. Wood

    Research output: Contribution to journalArticle

    75 Citations (Scopus)

    Abstract

    The partitioning of Fe and Mg between garnet and olivine has been determined as a function of Fe/Mg ratio at 1000°C and 9.1 kbar. Garnets of composition XgtFe = 0.90, 0.82, 0.60, 0.51, and 0.35 were mixed with olivines of various compositions in a ratio of 10:1 by mass, and the equilibrium olivine composition was determined within narrow limits. The magnitudes of the garnet interaction parameters are highly correlated with those of the olivine solution. However, assuming WolFeMg = WolMgFe = 9000 J/mol (two-site basis), we obtain WgtFeMg 2080 ± 1250 J/mol and WgtMgFe = 6350 ± 880 J/mol (three-site basis) at 1000°C. The standard-state free-energy change of the exchange reaction is calculated to be -2000 ± 800 J at 1000°C and 1 bar, in agreement with recent estimates of the free energy of almandine. -from Authors

    Original languageEnglish
    Pages (from-to)994-999
    Number of pages6
    JournalAmerican Mineralogist
    Volume74
    Issue number9-10
    Publication statusPublished - 1989

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