Horizontal shortening of upward-facing greenstone structures in the southern Superior Province, Canadian Shield

Abstract

Metavolcanics and clastic metasediments in parts of the Wabigoon and Shebandowan–Wawa subprovinces have been folded into tight upward-facing structures. Although the principal compressive strain is locally greater than 70%, the maximum value obtained for the overall horizontal shortening in a north–south direction is in the range of 40–60%. The actual horizontal shortening may be much less than this range unless there are large reverse faults or thrusts that have not been recognized to date.