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A study of diffusion and partition of 3d transition metal and rare-earth elements in the rock-forming minerals

3d过渡金属和稀土元素在造岩矿物中的扩散分配研究

基本信息

批准号：
09440193
负责人：
NAGASAWA Hiroshi
金额：
$ 9.54万
依托单位：
Gakushuin University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

The following results have been obtained in this study. 1) A new unhydrous Cu(2)-bearing silicate mineral and a Cu(2)-bearing ortho-pyroxene have been synthesized and their structures have been analyzed by single crystal X-ray diffraction. It is found that Cu mainly occupies a 4-fold coordinated site with square planar shape, while Mg occupies a 6-fold coordinated octahedral site in the new Cu-silicate structure. In the ortho-pyroxene structure Cu(2) occupies M2 site with square pyramidal 5-fold coordinated structure. The results reflect the Jahn-Teller nature of Cu(2) ion. 2) Diffusion of CO and Ni in olivine has been measured in the temperature range of 700-1000℃. It is found that the observed diffusion coefficients are consistent with those at high temperatures in terms of Arrhenius-relation. In gehlenite Ni and CO showed unexpectedly high diffusivities with unusually high activation energies, suggesting a unique mechanism for these elements. 3) Diffusion coefficients of the rare-earth elements (REE) have been measured. Individual REE showed different diffusivities depending to their ionic radii. Eu showed, under atmospheric condition, diffusion profiles composed of two segments corresponding to significantly different diffusivities. 4) Fractionation factor of D/H between hydrated CuClィイD22ィエD2 crystal and saturated CuClィイD22ィエD2 solution has been measured. Raman spectra of CuClィイD22ィエD2 crystal have been measured, and the fractionaton factors are calculated using the partition function relations. It is found that the observed and calculated fractionation factors agree reasonably well.

在本研究中获得了以下结果。1)合成了一种新的无水含Cu（2）硅酸盐矿物和一种含Cu（2）正辉石，并用X射线单晶衍射分析了它们的结构。结果表明，在新的铜硅酸盐结构中，Cu主要占据平面形状为正方形的4重配位，而Mg占据6重配位的八面体位置。在邻位辉石结构中，Cu（2）占据M2位，具有四方锥五重配位结构。结果反映了Cu（2）离子的Jahn-Teller性质。2)在700-1000℃温度范围内测量了CO和Ni在橄榄石中的扩散。结果发现，所观察到的扩散系数是一致的，在高温下的Arrhenius关系。在钙铝黄长石中，Ni和CO表现出出乎意料的高扩散系数，具有异常高的活化能，这表明这些元素具有独特的机制。3)测定了稀土元素的扩散系数。个别稀土元素表现出不同的扩散系数取决于其离子半径。Eu在大气条件下的扩散曲线由两段组成，对应于不同的扩散系数。4)测定了水合CuCl_（22）D_2晶体与饱和CuCl_（22）D_2溶液的D/H分馏因子。测量了CuCl_（12）D_22晶体的拉曼光谱，并利用配分函数关系计算了分馏因子。它被发现，所观察到的和计算的分馏因子相当好地同意。