EVOLUTION OF THE NORTH AMERICAN CORDILLERA

The Cordilleran orogen of western North America is a segment of the Circum-Pacific orogenic belt where subduction of oceanic lithosphere has been underway along a great circle of the globe since breakup of the supercontinent Pangea began in Triassic time. Early stages of Cordilleran evolution involved Neoproterozoic rifting of the supercontinent Rodinia to trigger miogeoclinal sedimentation along a passive continental margin until Late Devonian time, and overthrusting of oceanic allochthons across the miogeoclinal belt from Late Devonian to Early Triassic time. Subsequent evolution of the Cordilleran arc-trench system was punctuated by tectonic accretion of intraoceanic island arcs that further expanded the Cordilleran continental margin during mid-Mesozoic time, and later produced a Cretaceous batholith belt along the Cordilleran trend. Cenozoic interaction with intra-Pacific seafloor spreading systems fostered transform faulting along the Cordilleran continental margin and promoted incipient rupture of continental crust within the adjacent continental block.