RARE EARTH ELEMENT PARTITION COEFFICIENTS FROM ENSTATITE/MELT SYNTHESIS EXPERIMENTS - REE PARTITION COEFFICIENTS FOR PIGEONITE

Abstract

Enstatite (En80Fs19Wo01) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb, and Lu. The rare earth element concentrations were measured in both the basaltic glass by EMPA and the enstatite by SIMS. Rare earth element concentrations in the glass were determined by electron microprobe analysis with uncertainties less than two percent relative. Rare earth element concentrations in enstatite were determined by secondary ion mass spectrometry with uncertainties less than five percent relative. The resulting rare earth element partition signature for enstatite is similar to previous calculated and composite low-Ca pigeonite signatures, but is better defined and differs in several details. First, the enstatite LREE signature is steeper than for pigeonite. Second, the signature has a negative Eu anomaly which relates to oxygen fugacity and third, the dependence of the partition coefficients on alumina content is linked to crystal structural constraints.