Successive Geological Survey of Canada studies since 1959 document the mass transfer, about 1270 million years ago, of more than half a million cubic kilometres of molten rock from Earth’s mantle to the surface. The molten rock fed through a labyrinth of near-surface fissures and magma chambers, ranging over distances of 2000 km or more, to emerge at many locations in Nunavut as the Coppermine River lava flows.
The Muskox Intrusion, a magma chamber formed in a gigantic fissure, was one such conduit through which successive magma pulses reached Earth’s surface. Each pulse left a residue of crystals, preserving a record of the event’s evolution in the successive layers of the Muskox Intrusion. These layers were revealed from drill core studies from holes that penetrate the entire intrusion. The cores were drilled as part of Canada’s contribution, led by Charles Smith, to the International Upper Mantle Project, 1960-1970.
The Muskox Intrusion and related studies were an extraordinary achievement. They typify the Survey’s increasing shift toward collaborative scientific problem solving in the 20th century and this remains a hallmark of its research.
Category: Science Advances
Smith, C.H., Irvine, T.N., and Findlay, D.C., 1967. Geology, Muskox Intrusion, North Sheet, District of Mackenzie; Geological Survey of Canada, Map 1213A, scale 1:63 360. doi:10.4095/107495
Smith, C.H., Irvine, T.N., and Findlay, D.C., 1967. Geology, Muskox Intrusion, South Sheet, District of Mackenzie; Geological Survey of Canada, Map 1214A, scale 1:63 360. doi:10.4095/107496
Irvine, T.N., 1970. Crystallization Sequences in the Muskox Intrusion and other layered intrusions. 1. Olivine - pyroxene - plagioclase relations; Geological Society of South Africa Special Publication 1, p. 441–476.
Fahrig, W.F. and West, T.D., 1986. Diabase dyke swarms of the Canadian Shield / Essaims de dykes diabasiques du Bouclier canadien; Geological Survey of Canada, Map 1627A. doi:10.4095/133917
Baragar, W.R.A., Ernst, R.E., Hulbert, L., and Peterson, T., 1996. Longitudinal petrochemical variation in the Mackenzie dyke swarm, Northwestern Canadian Shield; Journal of Petrology, v. 37, p. 317–359. doi:10.1093/petrology/37.2.317