Investigation into the petrogenesis of Apollo 14 high-alumina basalts through textural and compositional analysis

The crystal size distributions (CSD) and major and trace element compositions of plagioclase crystals in Apollo 14 high-alumina basalts were measured in order to constrain the processes that affected the magma during crystallization. Results of the textural analysis suggest that high-Al volcanism became increasingly voluminous over time. Petrogenetic modeling of Group A basalts suggest that the magma formed from a parental composition with higher Sr and Ba abundances than suggested by whole rock analysis, and that plagioclase rim compositions could contain late stage melt inclusions, or could indicate possible open-system AFC processes. Petrogenetic modeling of Group B and Group C basalts suggest that the r-values fluctuated during their petrogeneses. Furthermore, most Group C equilibrium melt compositions fall beyond the FC and AFC trajectories, suggesting incorporation of an assimilant with lower Ba and higher Sr than suggested by whole rock studies.