Petrogenesis of the Apollo 14 high-alumina basalts: Implications from ion microprobe analyses

Geochimica et Cosmochimica Acta
By: , and 

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Abstract

In this study, ion microprobe analyses of individual minerals are used to investigate the petrogenesis of the Apollo 14 high-Al basalts. We use trace element concentrations from individual minerals in the Apollo 14 high-Al basalts to evaluate both endogenic and exogenic models. The data show that if the Apollo 14 high-Al basalts were produced by melting within the lunar mantle, these basalts cannot be related to one another by closed-system fractional crystallization of a single basaltic melt. Rather, the trace element data show that variable amounts of a KREEP component were added to the basalts by either assimilation, mixing into mantle sources, or impact melting. Single-stage assimilation–fractional crystallization models can only explain the data from this study if an excessively large mass of urKREEP is assimilated into the parent magma before olivine crystallization. Alternatively, the trace element data can be explained if the Apollo 14 high-Al basalts were produced by melting multiple Al-rich mantle sources that contain different amounts of urKREEP. Finally, for impact melting to be a relevant process, the data require that multiple large impact melts be formed from mixed KREEP-rich target lithologies. The resulting impact melts must then crystallize to produce basalts with igneous textures, high Al2O3 concentrations, uniform major element compositions, and a wide range of incompatible trace element concentrations.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Petrogenesis of the Apollo 14 high-alumina basalts: Implications from ion microprobe analyses
Series title Geochimica et Cosmochimica Acta
DOI 10.1016/j.gca.2005.08.008
Volume 69
Issue 24
Year Published 2005
Language English
Publisher Elsevier
Contributing office(s) Astrogeology Science Center
Description 15 p.
First page 5831
Last page 5845