Features of Distribution of Mercurian Concentric Basins on the Base of Messenger Data

MESSENGER images were investigated to expose the distribution of concentric basins on the surface of Mercury. We revealed 49 such objects with outer diameters from 64 km to 488 km, some of which have been formally named (e.g., Bach (214 km), Homer (319 km), Rachmaninov (306 km), Renoir (220 km), Chekhov (194 km), etc.). Fourteen concentric basins are unnamed. Concentric basins share the following common features: the diameter of the outer ridge is twice that of the inner ridge; the surface of the central depression is covered with a fewer number of craters than the surface between the inner and outer ridges; and chains of small craters and valleys usually surround such concentric basins. A histogram of the distribution of these basin dimensions shows that diameters from 160 km to 170 km and 190 km to 220 km are prevalent for concentric basins. About 70% of all concentric basins on Mercury are located in marginal zones between plains and highlands. We have compiled a map of the distribution of concentric basins on the Mercurian surface. It shows that the frequency of concentric basins in the western hemisphere is three times greater than the frequency in the eastern hemisphere. The comparison of concentric basins on Mercury, Moon and Mars is now complete.