The Impact of Slab Rollback on Earth's Surface: Uplift and Extension in the Hinterland of the North American Cordillera

Abstract

Slab rollback processes alter the intraplate force balance and buoyancy of the overriding plate, driving surface uplift or extension. From ca. 55–24 Ma, Farallon slab rollback produced migrating volcanism and sedimentation across the western United States as stress on the North American plate transitioned from subduction-driven compression to widespread extension. Hypotheses regarding rollback-driven surface deformation differ widely in timing and magnitude. Here we combine hydrogen isotope ratios with high-resolution geochronology to show that a high-elevation plateau extended westward from the Sevier-Laramide fold-thrust belt across Utah and eastern Nevada prior to slab rollback. Quantitative paleoelevation estimates show that this plateau had obtained over 80% of peak paleoelevations by middle Eocene. Slab rollback, heating, and lithospheric delamination generated 400–600 m of Oligocene surface uplift. Concurrent extension limited overall uplift and rollback-induced mantle flow likely contributed to the propagation of upper crustal extension that formed the Basin and Range province.