Geophysical Constraints on the Flexural Subsidence of the Denver Basin

The Denver Basin is an asymmetrical Laramide foreland basin covering portions of eastern Colorado, northwestern Kansas, southwestern Nebraska, and southeastern Wyoming. This study examines the hypothesis that the Denver basin is a flexural basin that subsided under the load of the Rocky Mountain Front Range and the topography of the Great Plains. The research tests three main corollaries of this hypothesis: the modern shape of the basin is due to flexure of the lithosphere under a surface load of the current topography, or there is also a buoyant subsurface load beneath the Rocky Mountains, or combination of both ideas. Gravity and topography data are used to develop a model of the current flexural condition of the lithosphere along the Denver Basin. Bouguer gravity power spectra are used to determine an average layered density model of the lithosphere. Three forward gravity models result in geologic cross-sections oriented perpendicular to the strike of the Bouguer gravity minimum associated with the western part of the basin. Flexural modeling is then used to estimate the magnitude and areal extent of the subsurface load.