Structural morphology and associated strain in the central Cordillera (British Columbia and Washington): Evidence of oblique tectonics

The central Cordillera developed during Early Jurassic to Late Cretaceous time as the continental edge was subducted under the exotic terranes of Quesnellia and Stikinia. The earliest Jurassic structures formed during prograde metamorphism and include cylindrical and double-verging folds that trend subparallel to the orogen. These structures are associated with mineral lineations and stretch values between 120% and 400% parallel to the fold axes. Later, disharmonic structures formed during the emergence of the crust, after the metamorphic peak and in response to decreasing P/T conditions.

Present tectonic models do not incorporate the kinematics capable of forming the early structures, and thereby only address the emergent phase. A scenario is offered which involves oblique subduction of the craton edge and which is kinematically compatible with the early structural morphology and associated strains.