Paleomagnetic evidence for the extent of Mackenzie igneous events

Abstract

North-northwesterly striking Mackenzie diabase dikes of middle-Proterozoic (Helikian) age are profuse in the western part of the Canadian Shield. Published paleomagnetic data on dikes of this trend in Mackenzie District, on the Muskox Intrusion, the Coppermine River volcanic rocks, and the Sudbury dikes suggest that they are all products of closely related igneous events. This paper presents paleomagnetic data that suggest that the intrusion of extensive diabase sheets in the East Arm of Great Slave Lake, and of dikes as far to the northeast as Melville Peninsula and as far to the southeast as Manitoba, were also parts of these events. The mean paleomagnetic pole position for the Mackenzie dikes and for related intrusive and extrusive rocks is [Formula: see text], 171 °W with [Formula: see text]. Radioactive age determinations, some of which are unpublished, indicate an age of about 1200 m.y. for the formation of these rocks. It is suggested that for convenience all of these apparently related intrusive and extrusive igneous episodes be referred to as Mackenzie igneous events.