Abstract

Many workers continue to model Nares Strait between Greenland and Ellesmere Island, Canada, as a plate boundary and locus of major Cenozoic compression and strike-slip, marked by the postulated Wegener (transform) Fault. This, despite continuity of Precambrian–Paleozoic provinces across the seaway including an undeformed Neoproterozoic mafic dyke swarm that crosses at a high angle. As a test of the speculative plate kinematic modelling, apatite fission track (AFT) dating was undertaken along a transect across the Paleoproterozoic shield of Smith Sound, at the south end of Nares Strait, running from sea level to ca. 600 m elevation and as much as 70 km inland on both sides. The shield is overlain by three sedimentary basins separated by major hiatuses. The AFT ages fall into two groups: 282 ± 34 and 650 ± 51 Ma. They indicate maximum depth was >4 km in the lower Paleozoic from both coasts to 50 km inland, and at >50 km inland temperatures were below the annealing interval throughout Phanerozoic time. During the past ca. 280 million years, the rocks of both age groups suffered only minor displacements. The ages form an unbroken, harmonious pattern along the transect with no evidence of thermotectonism since the Permo-Carboniferous. These quantitative data support the field mapping that demonstrates Smith Sound and environs constitute an intact crustal block unaffected by lithospheric fracturing. Nares Strait is not the site of a plate boundary. The Wegener Fault does not exist.

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