Colorado Rockies Uplift Hypothesis
Alternate Uplift Theory: Yellowstone-Class Mantle Event as the Primary Driver of Colorado Rockies Uplift
Abstract
This paper proposes that the Colorado Rockies were uplifted primarily by a massive, Yellowstone-class mantle event, rather than by traditional horizontal crustal compression. We suggest that a deep mantle upwelling event, occurring sometime after the Laramide orogeny (approximately 80 to 55 million years ago) and potentially continuing into the Miocene epoch (around 23 to 5 million years ago), produced a large-scale vertical force that drove regional crustal uplift without significant horizontal shortening. Secondary geologic features around the base of the uplift zone, including rifting, volcanism, and basin tilting, are interpreted as evidence of lateral flow and decompression associated with this mantle-driven uplift event.
Core Hypothesis
A high-energy mantle upwelling beneath central North America—comparable in scale to the modern Yellowstone plume—generated broad vertical uplift of the overlying lithosphere. This upwelling either failed to erupt or released only limited magma, with the bulk of its force expressed as doming. Peripheral deformation zones are understood as signs of mechanical and thermal adjustment to the uplift event, including lateral phase migration and crustal thinning at the margins.
Primary Evidence
Crustal Uplift Without Sufficient Shortening
– Much of the Rockies’ elevation is not explained by thrusting or folding.Low-Density Mantle Beneath the Rockies
– Seismic tomography reveals thinned, buoyant lithosphere inconsistent with thickened crust models.Miocene-Present Reactivation
– Evidence of renewed uplift millions of years after Laramide compression ended.Mismatch Between Elevation and Crustal Thickness
– High topography in areas lacking the thick crust expected from compressional uplift.
Secondary Effects (Peripheral Evidence of Mantle Dome Event)
Rio Grande Rift:
The Rio Grande Rift is interpreted as a zone of extension caused by lateral escape of mantle material from the base of the uplift dome. As vertical force accumulated beneath the Rockies, some of the pressure was released sideways, thinning the crust and creating a major rift zone.Raton-Clayton Volcanic Field:
The Raton-Clayton Volcanic Field likely represents edge volcanism triggered by decompression melting along the margins of the uplift zone. As mantle material flowed outward from the center, reduced pressure allowed magma to rise and erupt at weaker boundary points.High Plains Tilt:
East of the Rockies, the High Plains show signs of large-scale flexural warping or tilting. This is interpreted as the elastic response of the lithosphere to the vertical load of the uplift dome, bending under its weight and creating a regional tilt pattern.Basin and Range Extension:
The Basin and Range Province to the west may reflect a secondary phase of deformation: a peripheral collapse or mechanical recoil following the initial uplift. As the dome lost internal pressure or coherence over time, lateral tension caused widespread extension and thinning of the crust.Crustal Sills and Anisotropies:
Flat-lying sills and seismic anisotropies detected at the base of the crust suggest signs of lateral thermal flow. Instead of breaking through vertically, some of the mantle heat and material migrated horizontally, modifying the mechanical properties of the lower crust.Localized Gravity and Magnetic Anomalies:
Residual anomalies in gravitational and magnetic fields around the Rockies are interpreted as lasting signals of subsurface mass redistribution. These signatures may mark the edges where mantle material flowed outward or where density contrasts were frozen in place after the main uplift event.
These features support the concept that uplift was not contained, but produced lateral displacement, edge failure, and decompression melt around its periphery.
Testable Predictions
Geochronology will show phased uplift events separated from compressional tectonics.
Mantle-derived helium and deep isotopic signatures will be concentrated at the uplift’s margins.
Tomographic models will reveal domed or thinned lithosphere beneath the Rockies and outward-flowing structures.
Gravity and magnetic surveys will detect peripheral mass redistribution patterns consistent with mantle upwelling.
Fault patterns at the base will show radial or rift-aligned orientations.
Comparison Between the Laramide Uplift Model and the Mantle-Dome Uplift Model:
Driving Force:
In the traditional Laramide model, uplift is attributed to horizontal crustal compression, likely caused by the flat-slab subduction of the Farallon Plate beneath North America. In the mantle-dome model, by contrast, uplift results from vertical force driven by a deep, non-eruptive mantle upwelling, similar in scale to a Yellowstone-class event.Crustal Deformation:
The Laramide model predicts deformation dominated by fold and thrust belts, where the crust is pushed and crumpled horizontally. The mantle-dome model predicts doming of the lithosphere and extension at the dome’s edges, where excess pressure escapes laterally.Timing:
According to the Laramide model, major uplift occurred between approximately 80 and 55 million years ago. In the mantle-dome model, uplift could have occurred later, or even as a multi-phase process, with rejuvenated uplift episodes extending into the Miocene or more recent periods.Lithospheric Signature:
The Laramide model expects a thickened crust with a colder, stable mantle root beneath the uplifted region. In contrast, the mantle-dome model predicts a thinned crust overlying a hot or buoyant mantle, matching seismic observations of low-density anomalies beneath parts of the Rockies.Peripheral Effects:
Peripheral effects are minimal under the Laramide compression model. In the mantle-dome uplift model, significant peripheral effects are expected, including the formation of rift zones, episodes of decompression volcanism, and flexural warping of the adjacent lithosphere.
Conclusion
This alternative model accounts for major observational anomalies in the Rockies: high elevation without matching compression, post-orogenic uplift, and wide regional deformation. I propose that a Yellowstone-scale mantle event, occurring sometime after the initial Laramide orogeny (approximately 80 to 55 million years ago) and possibly extending into the Miocene epoch (around 23 to 5 million years ago), expressed its energy primarily as vertical uplift. This mechanism better explains the observed features than the standard Laramide compression model. Importantly, the model is testable using seismic, geochemical, and structural data, and it may apply to other similar intraplate uplifts globally.