Crustal magnetization beneath the aulneau and sabaskong batholiths, kenora and fort frances districts, Ontario, Canada☆
Abstract Gravity survey and aeromagnetic data over the Aulneau and Sabaskong batholiths, in the Kenora-Fort Frances districts of northwestern Ontario, have been modelled using crustal seismic surveys in the area as constraints. A crustal section was constructed from these results extending from the surface to the uppermost portion of the lower crustal layer. The batholiths are found to be relatively thin (average thickness 7 and 5 km, respectively). A prominent magnetic anomaly is centred in the contact zone between the batholiths, and overlaps both of them. Its source is interpreted as an intrusion in the lower part of the upper crustal layer. Surface measurements of magnetization and anomaly interpretation show that most of the magnetization of the Sabaskong body is concentrated in a linear central zone which extends through the body. An improved method of combining measurements of magnetization of rock samples with magnetic anomaly interpretation allows a more reliable calculation of the percent magnetite equivalent for buried rock units.