ArticlesTrace Elements

Rare Earth Elements in Returned Lunar Samples

Science  30 Jan 1970:
Vol. 167, Issue 3918, pp. 487-490
DOI: 10.1126/science.167.3918.487

Abstract

A linear correlation between concentrations of Sm and ratios of Sm to Eu for nine lunar samples suggests that those samples could correspond to liquids from equilibrium partial melting of a common source. On the basis of partition coefficients in terrestrial systems, the fraction of melting would not have exceeded about 15 percent and the immediate source could have been composed of olivine, orthopyroxene, and opaque minerals plus at least 25 percent feldspar, with at most a few percent calcic clinopyroxene and less than 1 percent apatite. The large Eu depletions could also have been produced by fractional crystallization if the ratio of Eu2+ to Eu3+ in lunar magmas significantly exceeds the values for terrestrial magmas.

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