The Fe–Mg exchange coefficient between olivine (ol) and melt (m), defined as KdFeT-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Fe}}^{T} {-} {\text{Mg}}}}$$\end{document} = (Feol/Fem)·(Mgm/Mgol), with all FeT expressed as Fe2+, is one of the most widely used parameters in petrology. We explore the effect of redox conditions on KdFeT-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Fe}}^{T} {-} {\text{Mg}}}}$$\end{document} using experimental, olivine-saturated basaltic glasses with variable H2O (≤ 7 wt%) over a wide range of fO2 (iron-wüstite buffer to air), pressure (≤ 1.7 GPa), temperature (1025–1425 °C) and melt composition. The ratio of Fe3+ to total Fe (Fe3+/∑Fe), as determined by Fe K-edge µXANES and/or Synchrotron Mössbauer Source (SMS) spectroscopy, lies in the range 0–0.84. Measured Fe3+/∑Fe is consistent (± 0.05) with published algorithms and appears insensitive to dissolved H2O. Combining our new data with published experimental data having measured glass Fe3+/∑Fe, we show that for Fo65–98 olivine in equilibrium with basaltic and basaltic andesite melts, KdFeT-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Fe}}^{T} {-} {\text{Mg}}}}$$\end{document} decreases linearly with Fe3+/∑Fe with a slope and intercept of 0.3135 ± 0.0011. After accounting for non-ideal mixing of forsterite and fayalite in olivine, using a symmetrical regular solution model, the slope and intercept become 0.3642 ± 0.0011. This is the value at Fo50 olivine; at higher and lower Fo the value will be reduced by an amount related to olivine non-ideality. Our approach provides a straightforward means to determine Fe3+/∑Fe in olivine-bearing experimental melts, from which fO2 can be calculated. In contrast to KdFeT-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Fe}}^{T} {-} {\text{Mg}}}}$$\end{document}, the Mn–Mg exchange coefficient, KdMn-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Mn}} {-} {\text{Mg}}}}$$\end{document}, is relatively constant over a wide range of P–T–fO2 conditions. We present an expression for KdMn-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Mn}} {-} {\text{Mg}}}}$$\end{document} that incorporates the effects of temperature and olivine composition using the lattice strain model. By applying our experimentally-calibrated expressions for KdFeT-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Fe}}^{T} {-} {\text{Mg}}}}$$\end{document} and KdMn-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Mn}} {-} {\text{Mg}}}}$$\end{document} to olivine-hosted melt inclusions analysed by electron microprobe it is possible to correct simultaneously for post-entrapment crystallisation (or dissolution) and calculate melt Fe3+/∑Fe to a precision of ≤ 0.04.

中文翻译：

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氧化还原对橄榄石与熔体之间Fe-Mg-Mn交换的影响和玄武岩氧气压计

橄榄石 (ol) 和熔体 (m) 之间的 Fe-Mg 交换系数，定义为 KdFeT-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Fe}}^ {T} {-} {\text{Mg}}}}$$\end{document} = (Feol/Fem)·(Mgm/Mgol)，所有的 FeT 都表示为 Fe2+，是使用最广泛的参数之一在岩石学中。我们探索了氧化还原条件对 KdFeT-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \ 的影响usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Fe}}^{T} {-} {\text{Mg }}}}$$\end{document} 使用实验，橄榄石饱和玄武岩玻璃，在很宽的 fO2（铁-方铁矿对空气的缓冲）、压力（≤ 1.7 GPa）、温度（1025–1425 °C）和熔体成分范围内具有可变的 H2O（≤ 7 wt%）。Fe3+ 与总 Fe 的比率 (Fe3+/∑Fe)，由 Fe K-edge µXANES 和/或同步加速器穆斯堡尔源 (SMS) 光谱确定，范围为 0–0.84。测量的 Fe3+/∑Fe 与已发布的算法一致 (± 0.05)，并且似乎对溶解的 H2O 不敏感。将我们的新数据与已发表的测量玻璃 Fe3+/∑Fe 的实验数据相结合，我们表明，对于与玄武质和玄武质安山岩熔体平衡的 Fo65-98 橄榄石，KdFeT-Mg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\ oddsidemargin}{-69pt} \begin{document}$${\text{Kd}}_{{{\text{Fe}}^{T} {-} {\text{Mg}}}}$$\end {document} 随 Fe3+/∑Fe 线性下降，斜率和截距为 0.3135 ± 0.0011。考虑橄榄石中镁橄榄石和铁橄榄石的非理想混合，采用对称正则解模型，斜率和截距为0.3642±0.0011。这是 Fo50 橄榄石的价值；在更高和更低的 Fo 值将减少与橄榄石非理想相关的数量。我们的方法提供了一种直接的方法来确定含橄榄石实验熔体中的 Fe3+/∑Fe，从中可以计算出 fO2。