Deep mantle forces and the uplift of the Colorado Plateau

Abstract

We introduce a quantitative model of global mantle convection that reconstructs the detailed motion of a warm mantle upwelling over the last 30 Ma towards the interior of the southwestern USA from observed present‐day mantle heterogeneity. The onset and evolution of uplift in the central Basin and Range province and Colorado Plateau during this time is determined by tracking the topographic swell due to this mantle upwelling. We show that: (1) the extension and basaltic volcanism (post 25 Ma) in the central Basin and Range coincides with the arrival and eastward progression of this upwelling, and (2) dynamic uplift of the southern Colorado Plateau, totaling about 1 km, transpired in the last 20 Ma. Since 10 Ma, the center of uplift continued northeastward from the southwestern rim of the plateau consistent with a young Grand Canyon model and eastward sweep of magmatism in the western Colorado Plateau.

Relation between alternations of uplift and subsidence revealed by Late Cenozoic fluvial sequences and physical properties of the continental crust

“…For instance , Granger et _ al. (2001) suggested that the alternation of base-level lowering and rising, evident in Moucha et _ al., 2009) or rebound following removal of part of the mantle lithosphere (e.g., Spencer, 1996;Levander et _ al., 2011).…”

Eroding dynamic topography

“…[13] Moucha et al [2009] and Robert et al [2011] propose, from backwards in time global convection modeling, the passing of a wave of dynamic topography through the Colorado Plateau to explain the 1400 m present-day mean altitude. The consequences of the wave propagation are best described in three phases: (i) global plateau uplift between 30 and 15 Ma; (ii) tilting of the plateau to the east between 15 and 5 Ma, and (iii) a back tilt of the western part of the plateau to the west since 5 Ma [Robert et al, 2011].…”

“…To achieve this, we will use a recently developed surface processes model (FastScape;Braun and Willett [2013]) that is highly efficient and can thus be used to study the erosion of very large scale ( 1000 km) surface topography at a resolution (<1000 m) that is sufficient to capture local slopes and drainage evolution. [7] Although mantle flow is relatively steady over tens to hundreds of millions of years, and the dynamic topography that it creates should therefore remain unchanged over the same periods of time, the relative motion of tectonic plates with respect to the underlying mantle can cause dynamic topography-as experienced by an observer attached to the moving surface plates-to be transient [Gurnis et al, 1998], as shown in numerous recent studies of reconstructed past dynamic topography [Moucha et al, 2009]. To illustrate this point, let us parameterize, to first order, the dynamic topography caused by a mantle plume or upwelling of width 2 beneath a plate that moves at a velocity v in the x-direction by the following Gaussian function:…”

Mantle dynamics, isostasy, and the support of high terrain

“…Many authors have suggested that elevation contrasts supported by tractions applied to the base of the lithosphere by the convecting mantle are of order a few hundred meters-the remaining <10% of the range of regional surface heights [e.g., Braun, 2010;François et al, 2014;Kaban et al, 1999Kaban et al, , 2004Le Stunff and Ricard, 1995;Solomatov, 2011, 2012;Christensen, 1994, 1999;White, 2000, 2002]. Some, however, contend that surface height variations > 1 km, and even 2 or 3 km, are maintained by stresses associated with mantle convection [e.g., Boschi et al, 2010;Flament, 2014;Flament et al, 2013Flament et al, , 2014Forte et al, 1993Forte et al, , 2010Gurnis, 1993;Husson et al, 2014;Lithgow-Bertelloni and Silver, 1998;Moucha and Forte, 2011;Moucha et al, 2009].…”