ABSTRACT

Partition coefficients for rare earth elements have been determined experimentally for diopside-liquid pairs by using two systems, Di₉₀-Ab_s-An₅ and Di₈₀-Fo₁₀-Qz₁₀ (wt%). The partition coefficient patterns obtained by partial melting of silicate system maintained beneath solidus have three remarkable features: (1) There is a peak in the vicinity of Gd. (2) The pattern for heavy REE span is warped up with increasing atomic number. (3) The small negative Ce anomaly is seen. These patterns can be interpreted as reflecting effect of overlapping two peaks which correspond to M1 and M2 site in the pyroxene structure. The effects of temperature and pressure on the partition coefficient pattern are qualitatively discussed.