Topographic controlled forcing of salt flow: Three‐dimensional models of an active salt system, Canyonlands, Utah

Abstract

The grabens within Canyonlands, Utah, is an active salt system primarily driven by differential unloading due to incision of the Colorado River. However, many other conditions exist in the region that potentially influence regional deformation, including the gentle dip of the evaporite deposits, unconfined salt within the river canyon, weaknesses in the overburden, and topographic gradients on various scales. Three‐dimensional numerical models were built to test the scale at which salt responds to these parameters individually and as a whole. Topography has a large influence on salt flow on both a regional and local scales and predicts the formation of existing structures in the region on consistent spatial scales without the influence of overburden weakening or salt geometry. Topography also has a large influence on the direction of salt flow, which acts to divert salt away from the canyon at the edge of the grabens and enhance salt flow within the grabens. Unconfined salt within the canyon regionally alters displacement rates and patterns, indicating a clear shift in strain before and after incision of the river into the Paradox Formation. On a local scale, there is a strong coupling between overburden weakening and salt flow patterns, where salt responds to individual structures and less to regional drivers. All these driving forces create an ensemble of feedback that alters the strain field and structural development through time.

Kinematic Response of Subaerial Salt Diapirs to Geomorphic, Tectonic and Climatic Regimes: Insights From Space‐Based Observations in the Western Kuqa Fold‐Thrust Belt, NW China

“…Additionally, two-dimensional monitoring uncovers a substantial contribution of horizontal motion at the DXGN and AWTN (Figure 3) and further reveals a gravity-spreading dominant salt system, similar to numerical model results of a salt system in Canyonlands, Utah (Kravitz et al, 2017).…”

Geomorphic and stratigraphic evidence of Quaternary diapiric activity enhanced by fluvial incision. Navarrés salt wall and graben system, SE Spain

“…Active salt flow may also result in complex secondary geomorphic effects. Lateral salt flow towards an erosional depression may cause the spreading of the overlying debuttressed brittle rocks, resulting in the development of a graben and horst morphostructure, which may cause the distortion of the pre-existing drainage, expressed through wind gaps and knickpoints (Trudgill, 2002;Gutiérrez et al, 2012;Kravitz et al, 2017). Some recent works nicely illustrate the use of deformed geomorphic markers dated by various geochronological methods to assess long-term rates of diapiric activity.…”

Active Steady‐State Creep on A Nontectonic Normal Fault in Southeast Utah: Implications for Strain Release in a Rapidly Deforming Salt System

“…There is widespread evidence in both Imperial Valley region and the Grabens that the low strength of the faults in the region contributes to the pattern of continuous creep. The northeast‐southwest striking faults in the Grabens likely nucleated along preexisting joints as shown by the orientation of active scarps exactly parallel to one of several regional joint sets (Cartwright & Mansfield, 1998; Kettermann et al, 2015; Kravitz et al, 2017; Mcgill & Stromquist, 1974; McGill & Stromquist, 1979; Moore & Schultz, 1999). In the Imperial Valley region, the joints are not pervasive and do not structurally influence the faults.…”

“…The difference in strike of the Imperial Valley fault relative to the Grabens (striking NE‐SW) was initially attributed to the salt pinchout to the southwest (Mcgill & Stromquist, 1974), though InSAR observations show this region has some of the highest regional displacement rates (Furuya et al, 2007). Displacement in the Imperial Valley region has more recently been related to breaching of the Paradox Formation in the Colorado River canyon and thicker overburden due to higher elevation of the region (Furuya et al, 2007; Kravitz et al, 2017). Numerical modeling indicates breaching of the salt layer in the Colorado River canyon initiated gravity gliding of the overburden toward the river, resulting in normal faulting along the Imperial Valley fault (Kravitz et al, 2017).…”

“…Displacement in the Imperial Valley region has more recently been related to breaching of the Paradox Formation in the Colorado River canyon and thicker overburden due to higher elevation of the region (Furuya et al, 2007; Kravitz et al, 2017). Numerical modeling indicates breaching of the salt layer in the Colorado River canyon initiated gravity gliding of the overburden toward the river, resulting in normal faulting along the Imperial Valley fault (Kravitz et al, 2017). We aim to understand the kinematics of fault displacement along the Imperial Valley fault in the context of the mechanics and slip behavior of active salt systems.…”