Shatter Cones at Sudbury

Abstract

The Sudbury structure has been interpreted by R. S. Dietz as an astrobleme. Fieldwork indicates that shatter cones are locally developed in a belt up to 11 miles wide around the outer contact of the nickel intrusive, and are confined to preintrusive rocks. Although apparently modified by folding, the cones show a strong preferred orientation toward the Sudbury Basin. Such a distribution and orientation are not incompatible with the astrobleme theory as expounded by Dietz. However, shatter-coning may not be uniquely characteristic of meteor impact, and it is hoped that further evidence will be forthcoming by which the theory may be properly evaluated.