Precambrian-Palaeozoic geology of Smith Sound, Canada and Greenland: key constraint to palaeogeographic reconstructions of northern Laurentia and the North Atlantic region

摘要

Nares Strait separating Greenland and northernmost Canada is floored by continental crust. Most palaeogeographic reconstructions of Laurentia and the North Atlantic region model the seaway as the site of massive sinistral strike-slip and/or compression/transpression, subduction and collision, the supposed manifestations of the hypothetical Wegener Fault. However, these reconstructions fail to take into account the bedrock geology that represents within-plate evolution. Both sides of Smith Sound, the southernmost part of Nares Strait, expose the same early Proterozoic to early Palaeozoic assemblages that are unaffected by seaway-related tectonism or thermal activity. Smith Sound is an intact crustal block or `linchpin' demonstrating that there was no independent Greenland plate. North-west Greenland was not a leading plate margin neither was Nares Strait the site of the plate boundary between Greenland and North America. The Wegener Fault does not exist. The Smith Sound linchpin constitutes a key constraint that must be respected in any palaeogeographic reconstruction of the region.