The Sr and Nd isotopic record of Apollo 12 basalts - Implications for lunar geochemical evolution

Alkali, alkaline earth, and rare earth element data are reported for several Apollo 12 basalts which are representative of the four Apollo 12 magma types. Results confirm the heterogeneity of the lunar mantle and show that the Sm/Nd ratio of at least the Apollo 12 ilmenite basalts was decreased by 13-24% during magma genesis. In addition, whole mare basalt Sm-Nd data are not collinear on an isochron diagram; thus it is no longer possible to explain these data via mixing of 'primitive material' and 'early differentiates' as in the hybridization and assimilation models.