Distribution of fault slip in outcrop-scale fault-related folds, appalachian mountains

Current kinematic models of ramp-related folds predict a direct relationship between ramp angle and fold shape and imply specific sequences of deformation. Analyses of outcrop-scale structures in the Valley and Ridge province of the Appalachians reveal configurations that depart from model predictions. The models fail to account for the presence of footwall synclines, and are inconsistent with measured displacement distributions on some natural faults. Observations support the interpretation that faults can grow by propagation both up- and down-dip from a nucleation point. Fault propagation in either direction may result in the formation of folds primarily on the side of the fault that is displaced in the direction of fault propagation.