Apollo 14 Mare basalts: Petrology and geochemistry of clasts from Consortium Breccia 14321

Eleven mare basalt clasts have been extracted from polymict lunar breccia 14321 for a combined petrologic and geochemical study by our consortium. Ten of these clasts are high‐Al, low‐Ti mare basalts similar to those discovered previously at Apollo 14. The other is a highly evolved tridymite ferrobasalt with low Al and intermediate Ti contents. A high‐Al, ilmenite ferrobasalt from lunar breccia 14305 is the most evolved high‐Al basalt described from the Apollo 14 site. The major and trace element characteristics of the basalts studied here allow them to be grouped into five compositional types that range from LREE‐depleted to LREE‐enriched. Some of these types may be related by varying percents of partial melting of the same source, but at least two separate sources that differ by a factor of two in incompatible trace element concentrations are required. The “14321‐type” basalts and vitrophyres have steep chondritenormalized HREE slopes and may have formed by assimilation of “Intermediate‐K Fra Mauro” KREEP, which is presumed to represent a partial melt of the lower crust. The age of these basalts (> 3.9 aeons) suggests that mare volcanism played an important role in the evolution of the early lunar crust.