Phase relations in the system MgO‐FeO‐SiO2 to 50 GPa and 2000°C: An application of experimental techniques using multianvil apparatus with sintered diamond anvils
Phase relations in the system MgO‐FeO‐SiO2 to 50 GPa and 2000°C: An application of experimental techniques using multianvil apparatus with sintered diamond anvils
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DOI：
10.1029/2008jb005891
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发表时间：
2009-02
影响因子：
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通讯作者：
Y. Tange;E. Takahashi;Yu Nishihara;K. Funakoshi;N. Sata
中科院分区：
文献类型：
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作者：
Y. Tange;E. Takahashi;Yu Nishihara;K. Funakoshi;N. Sata
[1]在1500°C和2000°C下，用烧结金刚石顶砧多顶砧装置研究了MgO-FeO-SiO_2系统在22 ~ 47 GPa压力下的相关系。合成的样品进行了分析，电子探针，分析透射电子显微镜，X射线衍射，同步辐射。测定了（Mg，Fe）SiO_3钙钛矿和（Mg，Fe）O镁橄榄石与SiO_2方石英共存时的单变量组成随压力和温度的变化。在2000°C和40 GPa以上的压力下，铁在钙钛矿中的最大溶解度随压力和温度的增加而逐渐增加，超过30 mol %;在22 ~ 35 GPa的压力下，铁镁在钙钛矿和镁橄榄石之间的分配存在明显的压力效应。随着压力的增加，镁橄榄石的铁含量从50摩尔%急剧增加到大于90摩尔%，并且钙钛矿和镁橄榄石之间的Fe-Mg分配系数KD =（XFePv/XMgPv）/（XFeMw/XMgMw）降低到小于0.05。这种显着的压力效应，在铁镁分配导致强烈的浓度，在下地幔的深度增加的镁橄榄石中的亚铁。
[1] Phase relations in the system MgO-FeO-SiO2 were investigated between 22 and 47 GPa at 1500°C and 2000°C using multianvil apparatus with sintered diamond anvils. Synthesized samples were analyzed with electron microprobe, analytic transmission electron microscopy, and X-ray diffraction using synchrotron radiation. Univariant compositions of (Mg,Fe)SiO3 perovskite and (Mg,Fe)O magnesiowustite coexisting with SiO2 stishovite were determined as functions of pressure and temperature. The maximum iron solubility in perovskite corresponding to the univariant composition gradually increases with increasing pressure and temperature to be more than 30 mol % at 2000°C and pressures above 40 GPa, and a significant pressure effect was found in Fe-Mg partitioning between perovskite and magnesiowustite in pressures between 22 and 35 GPa. The iron content of magnesiowustite dramatically increases from 50 to greater than 90 mol % with increasing pressure, and the Fe-Mg distribution coefficients between perovskite and magnesiowustite, KD = (XFePv/XMgPv)/(XFeMw/XMgMw), decrease to less than 0.05. This significant pressure effect in Fe-Mg partitioning causes strong concentration of ferrous iron in magnesiowustite with increasing depth in the lower mantle.