Cayley formation interpreted as basin ejecta, part B

Abstract

Improved information on the morphology and distribution of the Cayley Formation, provided by Apollo 16 orbital photography, leads to a concept in which the Cayley Formation was deposited as fluidized debris that traveled beyond the presently recognizable extent of the Imbrium Basin ejecta. By this hypothesis, each basin-forming event produced thick plains deposits in a belt peripheral to the continuous ejecta blanket and may have deposited a thinner layer in pools over the entire moon. Thus, each patch of terra plains is likely to be underlain by a sequence of fluidized ejecta deposits, which were derived from most or all multi-ring basins younger than the occupied depression. If the light color of the plains results from a high feldspar content of the excavated crustal rocks, an explanation of the absence of exposed pre-Cayley mare rocks may be that they are buried or dusted over.