Apollo and Luna Summary
Lunar geologic history and Apollo era paradigms
Intensive study of the Apollo and Luna sample collections has created a detailed history of the Moon with several specific highlights (e.g., S.R. Taylor, 1982):
- development of an early feldspathic crust that floated on a lunar magma ocean (LMO)
- basaltic magmatism that lasted from 4.4 to 3.2 Ga
- bimodal high and low Ti volcanism
- an incompatible element enriched residual liquid from crystallization of the LMO
- a spike in the impact flux, the terminal lunar cataclysm, at 3.9 Ga
These models and ideas have been summarized in several publications (e.g., BVSP, 1981; Origin of the Moon, 1985; Wilhelms, 1987; Lunar Source Book, 1991; New Views of the Moon, RIMG New Views of the Moon volume, 2006).
However, the Apollo and Luna samples are from only a small region on the Moon (Fig. 6), close to the Procellarum KREEP Terrane (Fig. 7), and it has even been argued that many of the Apollo sites have been affected by the Imbrium impact basin (Korotev et al., 2003). It follows that the samples from these missions have provided only a limited understanding of the origin and evolution of the Moon. The strength of the meteorite collections is that they provide a more random and representative sampling of the lunar surface and thus will be of great value in determining the origin and geologic history of the Moon.
Figure 6: Map of the Moon showing the small region that has been sampled by Apollo (A) and Luna missions (L) (from Warren and Kallemeyn, 1991)
Figure 7: The map produced from Lunar Prospector data showing the locations of Apollo and Luna sample sites (from Korotev et al., 2003)