Elastic strain recovery in Proterozoic rocks near Elliot Lake, Ontario

Elastic strain recovery in boreholes was measured in underground mines near Elliot Lake, Ontario, Canada. Maximum elastic strain recovery is horizontal and parallel to the local postorogenic joint sets. Close to the mine workings this relationship is disturbed by the stress field induced by mining. The magnitude of the stress tensor increases with depth. The in situ stresses are interpreted as remanent tectonic stresses that were imprinted onto the rock during the Hudsonian orogeny (1700 m.y. ago). Unloading and reorientation of the stresses was achieved by long-lived arching along an easterly trending axis. A parallelism of maximum elastic strain recovery (maximum compressive stress) and axes of regional arching in eastern North America is inferred from available data.