Alpine model for the internal metamorphic zones of the North American Cordillera

Abstract

The tectonic significance of the internal metamorphic zones of the North American Cordillera remains elusive. We propose a general interpretation in which the tectonic features (pervasive unidirectional transverse lineation, recumbent folding, eastward thrusting) of the Shuswap Complex (Canada) are related to a large-scale intracontinental alpine-type eastward shearing. This shearing results from the Jurassic collision between the allochthonous Stikine block and the North American craton, after a westward Triassic subduction. We extend this model to the United States Cordillera, despite some differences due to the late occurrence of a major extension.