Local structures of Ca, Ti and Fe in meteorite fusion crusts
Local structures of Ca, Ti and Fe in meteorite fusion crusts
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陨石熔壳中 Ca、Ti 和 Fe 的局部结构
DOI：
10.1088/1742-6596/712/1/012095
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
K Sugiyama
中科院分区：
文献类型：
--
作者：
T Tobase;A Yoshiasa;T Hiratoko;H Hongu;H Isobe;A Nakatsuka;H Arima;K Sugiyama
用Ca、Ti、Fe K边XANES和EXAFS研究了陨石熔融壳的局部结构。陨石进入大气层后，在极高的温度和较大的温度梯度下，表面发生熔化和挥发。这一研究表明，陨石熔融壳具有独特的局部结构。熔融壳的局部结构与玻璃陨石不同，特别是在Ca XANES谱中边缘上升侧翼的肩部强度。这与进入大气层时熔融时硅挥发引起的化学成分变化相一致。陨石熔融壳中Fe 3+/（Fe 2++ Fe 3+）比值较高，表明陨石熔融壳是在大气氧化条件下形成的。陨石熔结壳中的Ca-O距离为2.612。66 A，比其他天然玻璃长得多。熔融壳经历了极高的温度和短暂的淬火时间，具有独特的局部结构。XAFS方法是鉴别陨石熔融壳和天然玻璃的有效方法。
The local structures of meteorite fusion crusts were studied by Ca, Ti and Fe K-edge XANES and EXAFS spectroscopy. The surface of meteorites were melted and volatilized with extreme high temperature and large temperature gradient when meteorites were rushed into atmosphere. This study indicated that meteorite fusion crusts have unique local structures. The local structures of fusion crusts differ from tektites especially in intensity of the shoulder in the rising flank of the edge in Ca XANES spectra. It is consistent with chemical composition change by the volatilization of Si at fusion during atmospheric entry. The high estimated Fe 3+/(Fe 2++ Fe 3+) ratio in meteorite fusion crusts indicates that meteorite fusion crusts are formed into atmospheric oxidation condition. The Ca-O distances in meteorite fusion crusts are 2.612. 66 A and are extremely longer than in other natural glasses. The fusion crusts have unique local structure since they experienced extremely high temperature and short quenching time. The XAFS method is effective in distinction of meteorite fusion crusts and classification of natural glass.