The distribution and origin of lunar light plains around Orientale basin

Lunar light plains are relatively flat, smooth to gently rolling deposits that occur in crater floors and other topographic lows in the lunar highlands, with albedo values comparable to surrounding highland terrain. Once interpreted to be the product of highland volcanism, Apollo 16 samples from the light plains of the Cayley Formation led to the interpretation that most light plains form from the deposition of fluidized basin ejecta. Conflicting relative age estimates suggest that light plains are ejecta from the Orientale and Imbrium basins, or from a larger number of impact events combined with possible volcanic eruptions. Here we examine the distribution, variability, and origin of light plains associated with the Orientale basin using data from the Lunar Reconnaissance Orbiter Camera (LROC). We find that the distribution, composition, and age of the light plains to the north and northwest of the Orientale basin are consistent with an origin with the formation of Orientale. In this case, the Orientale basin-forming impact significantly altered the surface within four basin radii from the rim.