Asymmetric rift interpretation of the western North American margin

Geologic evidence shows that the Neoproterozoic rift margin of western North America formed as a set of asymmetric detachments, leading to alternating upper- and lower-plate domains distinguishable by the width and gradient of the continental margin, thickness of overlying strata, uplift-subsidence history, relative structural complexity, and presence or absence of exposed lower-crustal rocks. The gradient of the cratonal margin is a key feature related to the transition between continental and oceanic crust. The sinuosity of the Cretaceous-Tertiary thrust-belt front, the distribution of basement exposures, and patterns of miogeoclinal deposition may therefore be inherited from the original asymmetric Neoproterozoic rift geometry. -from Authors