Post-rift deformation of the Midcontinent rift under Grenville tectonism

Using a thin-viscous-sheet model, we investigate the hypothesis that compressive stresses resulting from the Grenville orogeny caused uplift along the Midcontinent rift. The objective of this study is to investigate factors involved in shaping the post-rift structure of the Midcontinent rift including: the size and location of the colliding terranes and the convergence angle between the colliding terranes and the North American craton. We find a linear relationship between the size of the terrane and the deformation within the Midcontinent rift. The calculations predict comparable deformation along both the eastern and western arms of the Midcontinent rift. Our results demonstrate that the geologically indicated NE-SW deformation can be produced without a multistage compression event because of the nonlinear interaction of far-field compressive stress and the mechanically weak rift. Therefore, it is not possible to determine which compression direction is representative of the compression associated with the Grenvillian orogenic event based on the post-rift pattern of deformation. (C) 2002 Elsevier Science B.V. All rights reserved.