Mackenzie sills (1270 Ma, Northwest Territories, Canada)

Cliff-forming sills, related to the 1270 Ma Mackenzie igneous event, cutting strata of Athapuscow Basin, East Arm of Great Slave Lake, Northwest Territories, Canada. Photo by L.B. Aspler.

see: Baragar WRA, R.E. Ernst, L. Hulbert, T. Peterson, Longitudinal petrochemical variation in the Mackenzie dyke swarm, northwestern Canadian Shield. J. Petrol. 37: 317-359, 1996.