Collision Catalyzes Cordilleran Orogeny

This new Special Paper from The Geological Society of America describes an iconoclastic model for the Cretaceous-Tertiary development of the Cordilleran orogen.

Most models for the development of the Cordilleran orogen invoke Late Jurassic-Cretaceous intraplate, back-arc shortening above an eastwardly-dipping subduction zone. Author Robert S. Hildebrand of Utah State University argues that a simple collisional model, in which the leading edge of North America was subducted to the west beneath a segmented, arc-bearing microcontinent, better fits the data.

Hildebrand theorizes that westerly dipping subduction beneath an exotic ribbon continent named Rubia was followed by development of an eastward-dipping subduction zone outboard of the collision zone. This model explains the origin of Laramide thick-skinned deformation, Cordilleran-type batholiths, early Tertiary metamorphic core complexes, Basin and Range extension, porphyry copper deposits, and the Pelona-Orocopia-Rand schists, and it helps resolve the longstanding Baja-British Columbia controversy.

Source: Geological Society of America