Retrospective on "Low-angle (denudation) faults, hinterland of the Sevier orogenic belt, eastern Nevada and western Utah" by Richard Lee Armstrong

Abstract

The 1960s and early 1970s brought sweeping new syntheses of the Cordilleran orogen as having developed primarily in response to the motions of oceanic plates to the west. The main conclusions of these syntheses were that the Cordilleran miogeocline resulted from Neoproterozoic continental rifting; magmatic systems are a signature of subducting slabs beneath the continent; and variably oblique plate convergence was responsible for coastwise shearing and progressive accretion of large, sometimes far-traveled crustal fragments onto the continental margin through most of Phanerozoic time. The novelty of these concepts is clear from the pre-1960s literature, which contains only rare allusions to ideas that might be considered similar. Afterward, the nature of the debate illustrated their profound acceptance. Are the magmas arc or backarc? Was there just one Neoproterozoic rifting event? How far had the westernmost accreted blocks traveled? That none of these comparatively second-order issues are resolved after some three decades of research is humbling testimony to the progress represented by the early syntheses.