Impacts & Mare -- Earth and Moon
The Sudbury structure is one of North America’s oldest and largest impacts. The original size of the structure has been estimated at 220 km and the age at 1.85 b.y. Regional tectonism has distorted the crater into an ellipse, the center of which is a 27 X 59 km basin that contains predominantly nickel ore. The origin of this ore body is disputed. The leading theory is that the ore body is the result of an impact that melted upper and lower crustal material. A similar theory of an impact creating volcanism was proposed for the Moon. In contrast, it is now believed that the filling of impact basins (3.8 to possibly as recently as 1.5 b.y.) came long after the basins themselves were formed (~3.85 b.y.). Mare Moscoviense is located on the lunar far side and is 221 km in diameter.
