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Decipherment of important reoord concerning the earth and planet activity that remains in local structure of trace elements

破译保留在微量元素局部结构中的有关地球和行星活动的重要记录

基本信息

批准号：
17204049
负责人：
YOSHIASA Akira
金额：
$ 29.54万
依托单位：
Kumamoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

This research is an attempt to read the important record concerning the earth and planet activity that remains in local structure of trace elements. Information on a precise local structure around a specific kind element is obtained by X-ray abscxption spectroscopy and the X-ray diffraction methods. Physical properties measurement, electronic state measurements and structure analyses are put into close contact to investigate details of the melts, amorphous and crystals materials under extreme conditions. The experiments are performed in-situ, by using world's top level equipments such as Spring-8 synchrotron facilities. The research aims the construction of the theory that links the nanometer-level structure, the macroscopic properties and the textures and history in multi element and multi phases such as the Earth's interior.Local structure of trace elements in K-T boundary clays was studied by XAFS spectroscopy. Arsenic as an excessively concentrated element occupies the As04 tetrahedral site of a mineral in K-T boundary clays and the characterization of XAFS spectra agree well with the values of As(+5)minerals according to the comparison with several types of arsenic minerals. The guest Fe elements in Al2SiO5 kyanite have higher-valence states of tetravalent and the Fe-0 bond distance is of 1.865(7)(A)because kyanite had been experienced the high pressure and high oxidized conditions. The local structure and reactivity of noble gas in minerals has been investigated. Several kinds of noble gas-doped minerals were synthesized under high pressures and temperatures and were subjected to mass spectroscopy and XAFS. Interestingly, the atomic distances between noble gas and neighboring atoms appeared to be shorter than the distances expected for the case of simple adsorption. These results suggest that noble gas might be bound in the samples with interaction stronger than the adsorption and/or exist in the internal sites of the structure of the host minerals.

这项研究试图解读残留在微量元素局部结构中的有关地球和行星活动的重要记录。通过 X 射线吸收光谱和 X 射线衍射方法可以获得特定种类元素周围精确局部结构的信息。物理性能测量、电子态测量和结构分析紧密结合，研究极端条件下熔体、非晶和晶体材料的细节。实验采用Spring-8同步加速器等世界顶级设备在原位进行。该研究的目的是构建连接纳米级结构、宏观性质以及地球内部等多元素、多相的纹理和历史的理论。通过XAFS光谱研究了K-T边界粘土中微量元素的局部结构。砷作为一种富集元素，在K-T边界粘土中占据了矿物的As04四面体位点，通过与几种类型的砷矿物的比较，XAFS光谱表征与As(+5)矿物的值非常吻合。由于蓝晶石经历了高压和高氧化条件，Al2SiO5蓝晶石中的客体Fe元素具有四价的较高价态，Fe-0键距为1.865(7)(A)。研究了矿物中稀有气体的局部结构和反应性。在高压和高温下合成了几种稀有气体掺杂矿物，并进行了质谱和 XAFS 分析。有趣的是，惰性气体和相邻原子之间的原子距离似乎比简单吸附情况下预期的距离短。这些结果表明，稀有气体可能以比吸附更强的相互作用结合在样品中和/或存在于宿主矿物结构的内部位点中。