The distribution of Sr and REE between diopside and silicate liquid

Abstract

Distribution coefficients (weight concentration in the solid divided by concentration in the liquid) have been determined experimentally in diopside‐liquid pairs. Experiments were carried out in air at 1265 °C in the system NaAlSi 3 O 8 ‐CaAl 2 Si 2 O 8 ‐CaMgSi 2 O 6 at the two bulk compositions: 5‐30‐65 and 32‐11‐57 (weight percentage of components in the order given above). Small differences are observed in the distribution coefficients between the two compositions. Mean values of the coefficients in the first system are: Sr=.078, La=.069, Ce=.098, Nd=.21, Sm=.26, Eu=.31, Gd=.30, Dy=.33, Er=.30 and Lu=.28. At low oxygen fugacities of 10 −9.5 and 10 −12.5 atmospheres the distribution of Eu between diopside and liquid develops a “negative Eu‐anomaly” with coefficients of .23 and .12 respectively.