A precambrian suture in the Canadian shield

Linear belts of distinctive oceanic and geosynclinal deposits found on the continents have recently been interpreted as marking sutures or join lines between collided continents. Examples include the Indus Suture, the boundary between collided Mesozoic Indian and Laurasian continents, and the ophiolite belts of the Alps between early Tertiary and Mesozoic European and African continents. Both these sutures and other described examples are of Phanerozoic age although it has been suggested that older sutures exist.

A similar hypothesis to explain the nature of the boundary between the Churchill and Superior structural provinces is proposed which assumes that the mechanisms of plate tectonics were active in Aphebian times (2390−1640 my).

It is suggested that the Slave and Superior Archean protocontinents were once separated by Aphebian seas. The embryo Churchill Province at that time comprised a number of Archean continental fragments with associated island arcs, trenches and sedimentary basins. These coalesced during closure of the seas between the converging Slave and Superior protocontinents. Convergence was accomplished by consumption of oceanic lithosphere along several Aphebian subduction zones which caused the Hudsonian orogeny, formation of the Churchill Province, and tectonic deformation at the edges of the collided protocontinental blocks.

The suture peripheral to the Superior craton is the most easily recognized and is characterized by Aphebian geosynclinal and oceanic sedimentary, basic volcanic and ultramafic rocks, or their metamorphosed equivalents. The proposed suture extends from the Manitoba Nickel belt, via the Split Lake-Fox River region and eastern Hudson Bay, to the Cape Smith-Wakeham Bay belt and the Labrador Trough, Quebec.