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The North American Cordillera in Canada and Alaska has been investigated through coincident and coordinated geological, geochemical, and geophysical studies along three corridors: (1) the Lithoprobe Southern Cordillera transect, (2) the ACCRETE and Lithoprobe Slave-Northern Cordillera Lithospheric Evolution (SNORCLE) transects, and (3) the Trans-Alaska Crustal Transect (TACT) program. Seismic-reflection and refraction experiments are integral to these studies and contribute to lithospheric-scale models that enable orogen-parallel comparisons to be made. Primary observations include three points: (1) Outward-verging, crustal-scale décollements are characteristic features of the orogen. The three trans-Cordillera transects exhibit decoupling zones that dip away from the Foreland belt to the lowermost crust or Moho. These inboard décollements above an indentor or cratonic backstop extend 500–600 km downdip in the Canadian Cordillera and 250 km downdip in the Alaskan Cordillera. The active subduction megathrusts form opposing décollements and generate structures in the overriding crust that mirror those above the facing intracrustal ramps. (2) Oblique convergence resulting in significant transpressional, transtensional, and orogen-parallel motion has yielded four major transcurrent fault systems that penetrate the entire crust and are associated with tectonic boundaries. (3) Beneath the entire Canadian Cordillera, the Moho remains remarkably flat and shallow despite the variety of ages, terrane compositions, and tectonomagmatic deformations spanned by the seismic corridors. These observations indicate that the Moho is an active, near-solidus, deformation zone that represents a young, re-equilibrated crust-mantle boundary. Beneath Alaska, crustal roots are observed over the subduction zone and at the indentor wedge, but the interior of the orogen also exhibits thin crust.

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