The Global Distribution of Lunar Light Plains From the Lunar Reconnaissance Orbiter Camera

We present the first globally consistent map of lunar light plains from Lunar Reconnaissance Orbiter Camera mosaics 100 m/pixel. Based on this map, ~70% of light plains are likely related to the Orientale and Imbrium basins; however, many light plains deposits originated with local- and regional-scale impacts, nonmare volcanics (i.e., the Apennine Bench Formation), as well as ancient impact melt deposits that lack diagnostic small-scale features. Compositional evidence suggests that the light plains associated with basins (i.e., Cayley plains) form through substantial mixing with local materials, implying that ballistic sedimentation is a primary formation mechanism. Based on the distribution of light plains with respect to the Orientale and Imbrium basins, the stratigraphic extent of an individual basin extends to at least four basin radii. As such, the South Pole-Aitken basin modified at least 80% of the lunar surface. This work suggests that the entire lunar surface was modified to varying degrees at the time of large basin formation. This has implications for sample interpretations because any highland site within four radii of a large basin could potentially contain primary basin material or more local material that was redeposited by secondaries, neither of which is necessarily representative of the terrain upon which they are found.