Partitioning of iron between perovskite/postperovskite and ferropericlase in the lower mantle
Partitioning of iron between perovskite/postperovskite and ferropericlase in the lower mantle
复制标题
下地幔中铁在钙钛矿/后钙钛矿和方镁石之间的分配
DOI：
10.1029/2008jb005730
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发表时间：
2008
影响因子：
--
通讯作者：
Y. Ohishi
中科院分区：
文献类型：
--
作者：
R. Sinmyo;K. Hirose;D. Nishio–Hamane;Y. Seto;K. Fujino;N. Sata;Y. Ohishi
[1] 钙钛矿/后钙钛矿和方镁石之间的 Fe2+-Mg 分配系数 (KD) 在 (Mg0.9Fe0.1)2SiO4 块状组合物中测定。在激光加热金刚石砧室 (LHDAC) 中在 36 至 128 GPa 和 1760-2170 K 之间进行高压和高温实验。使用透射电子显微镜（TEM）和场发射型扫描电子显微镜（FE-SEM）对回收的样品进行化学分析。由于激光加热过程中相对较大的温度梯度，所有样品的铁含量表现出很强的不均匀性，在热点中心贫化，在边缘富集。从共存的钙钛矿/后钙钛矿和铁方镁石酶测量的 KD 值在每个样品中显示出明显非常大的变化，这可能是以前使用 LHDAC 技术测量的 KD 之间存在相当大差异的根源。然而，从保留原始本体成分的样品的特定部分获得的数据可以代表平衡分配。目前的结果表明，在整个较低地幔压力的给定温度下，钙钛矿/后钙钛矿和铁方镁石之间的铁分配变化很小。铁的电子跃迁和后钙钛矿相变对铁的分配影响很小。
[1] The Fe2+-Mg distribution coefficients (KD) between perovskite/postperovskite and ferropericlase were determined in a (Mg0.9Fe0.1)2SiO4 bulk composition. High-pressure and high-temperature experiments were carried out between 36 and 128 GPa and 1760–2170 K in a laser-heated diamond anvil cell (LHDAC). Chemical analyses were made on recovered samples with transmission electron microscope (TEM) and field-emission-type scanning electron microscope (FE-SEM). All the samples exhibited a strong heterogeneity in iron content caused by relatively large temperature gradient during laser-heating, being depleted at the center of the hot spot and enriched at the margin. The KD values measured from coexisting perovskite/postperovskite and ferropericlase showed apparently very large variation in each sample, which could be the source of considerable discrepancy among previous measurements of KD using the LHDAC techniques. Nevertheless, the data obtained from a specific portion of the sample that retained the original bulk composition may represent the equilibrium partitioning. Present results demonstrate that the iron partitioning between perovskite/postperovskite and ferropericlase changes little at a given temperature throughout the lower mantle pressures. Both electronic transition of iron and postperovskite phase transition have small effects on iron partitioning.