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

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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.