Tectonics of the Colorado Plateau and Its Margins

Abstract

The Cenozoic Colorado Plateau physiographic province overlies multiple Precambrian provinces. Its ∼2-km elevation rim surrounds an ∼1.6-km elevation core that is underlain by thicker crust and lithospheric mantle, with a sharp structural transition ∼100 km concentrically inboard of the physiographic boundary on all but its northeastern margin. The region was uplifted in three episodes: ∼70–50 Ma uplift above sea level driven by flat-slab subduction; ∼38–23 Ma uplift associated with voluminous regional magmatism and slab removal, and less than 20 Ma uplift associated with inboard propagation of basaltic magmatism that tracked convective erosion of the lithospheric core. Neogene uplift helped integrate the Colorado River from the Rockies at 11 Ma to the Gulf of California by ∼5 Ma. The sharp rim-to-core transition defined by geological and geophysical data sets suggests a young transient plateau that is uplifting as it shrinks to merge with surrounding regions of postorogenic extension. ▪ The Colorado Plateau's iconic landscapes were shaped during its 70-million-year, still-enigmatic, tectonic evolution characterized by uplift and erosion. ▪ Uplift of the Colorado Plateau from sea level took place in three episodes, the youngest of which has been ongoing for the past 20 million years. ▪ Tectonism across the Colorado Plateau's nearest plate margin (the base of the plate!) is driving uplift and volcanism and enhancing its rugged landscapes. ▪ The bowl-shaped Colorado Plateau province is defined by ongoing uplift and an inboard sweep of magmatism around its margins. ▪ The keel of the Colorado Plateau is being thinned as the North American plate moves southwest through the underlying mantle. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Basin record of a Miocene lithosphere drip beneath the Colorado Plateau

“…There has been no convincing explanation for the sequence of events at Bidahochi Basin, particularly the enigmatic local subsidence from 16 to 6 Ma after widespread exhumation and surface uplift across the Colorado Plateau 20 , 39 . Early studies presumed that volcanism and basin development were unrelated 30 and attributed paleolake formation to transitions in hydrologic or paleoclimate conditions, such as damming of the Little Colorado River 40 , 41 .…”

“…The Bidahochi Basin also cannot be attributed to normal faults, which are pervasive along the margins of the Colorado Plateau but uncommon within its core (yellow lines, Fig. 1a ) 20 . Other authors extrapolated the modern elevation of the Bidahochi Formation to argue for a large paleolake filling the entire modern-day basin up to that level (Fig.…”

“…There is a growing body of evidence that lithosphere removal contributed up to 0.5-1.5 km of surface uplift of the Colorado Plateau during the past ~20 Myr 4 , 7 , 15 , 16 , although the exact timing and spatial pattern of uplift remain controversial 4 . Seismic receiver functions and P-, S-, and Rayleigh-wave tomography show that the mantle lithosphere beneath the margins of the plateau (as well as the southern Rocky Mountains and the Mogollon highlands region, which likely shared an uplift history with the Colorado Plateau) has been thinned and replaced by hotter and more buoyant asthenosphere 17 – 20 . Vp perturbations reveal a ~ 120-190 km-wide, high-velocity anomaly (the Escalante anomaly) that is elliptical in map view and extends greater than 200 km deep near the Arizona-Utah border (Fig.…”

Diverse Styles of Lithospheric Dripping: Synthesizing Gravitational Instability Models, Continental Tectonics, and Geologic Observations

“…Numerical models also suggest that instability of a lithospheric step migrates horizontally in a manner intermediate to delamination and dripping (Beall et al., 2017). Given the asymmetric nature of convective instabilities on the edges of the Colorado Plateau (Karlstrom et al., 2022), more suggestive of delamination than dripping, we exclude the S Colorado Plateau events from our analysis.…”

Plan‐Form Evolution of Drainage Basins in Response to Tectonic Changes: Insights From Experimental and Numerical Landscapes

“…First, terrains that emerge from subdued topography in response to uniform uplift, resulting in basin emergence and growth, in parallel to shrinking of an uplifted plateau. While this represents an idealized setting, basins that incise into high-elevation low-relief plateaus are widely documented along passive and rifted margins (Harel et al, 2019;Wang & Willett, 2021) and in association with high mountainous terrains (Karlstrom et al, 2022;Montgomery et al, 2001;Walcott & Summerfield, 2009). The second scenario is terrains 10.1029/2022JF006876 3 of 24 subjected to an uplift gradient in the form of tilting.…”