Abstract

Alpine glacial erosion may strongly influence mountain building through erosionally driven rock uplift and relief production. In this paper I use a three-dimensional model for the flexural-isostatic response of the lithosphere to estimate the potential for late Cenozoic erosionally driven rock uplift in the western United States. Specifically, I present a map of the ratio of erosionally driven rock uplift to glacial erosion for this region. This ratio depends on the magnitude of the flexural bending stresses that act to limit differential uplift. The map is created by constraining the extent of Pliocene–Quaternary alpine glacial erosion in the western United States and solving the three-dimensional flexure equation for the resulting lithospheric deflection. The map indicates that the magnitude of erosionally driven uplift depends sensitively on the size of the glaciated range and the presence of nearby glaciated ranges. As a result, regional-scale patterns must be considered in order to correctly estimate local amounts of erosionally driven rock uplift. The ranges in the western United States with the greatest ratios of uplift to erosion are the San Juan Mountains and the Yellowstone Plateau–Absaroka Range, because these are extensively glaciated and have glaciated ranges nearby. In contrast, the Wind River Range and Sierra Nevada have ratios of uplift to erosion that are only half as large. These results identify which ranges likely underwent the greatest erosionally driven uplift and relief production and provide a widely applicable technique for modeling the flexural-isostatic response to loading and unloading in three dimensions.

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