A statistical study of Mercurian crater classes applied to the emplacement of the intercrater plains.

Two principal processes have been invoked for emplacement of the intercrater plains: (1) basin ejecta and autochthonous surface materials reworked by that ejecta or (2) volcanic flows. A new approach was taken: the multivariate statistical analysis of crater class. The results of the analysis constrain the formative process of the intercrater plains units to have affected craters on both terrains in a similar manner. Any emplacement process brief in temporal extent (compared to the period of late heavy bombardment), such as emplacement of ejecta from a single event or a brief period of extensive volcanism, violates this constraint. This analysis is briefly discussed.