Several fault-related folds were examined in outcrops of Devonian, Silurian and Pennsylvanian rocks in the Valley and Ridge and Appalachian plateau provinces. These structures exhibit features such as footwall folds, en echelon ramps, and non-uniform variations in fault displacement, that are not represented in existing geometric and kinematic models.
These features can be accounted for by considering the mechanical response of a sedimentary section to fault propagation and displacement. Fault-fold interaction is dependent upon the relative ductility, thickness and stratigraphic order of the deformed sedimentary section. Analyses of fault-related folds at Eagle Rock and Bergton, VA, and Dunlap, TN, are interpreted to suggest that folding will be associated with faulting where: i) the initial ratio of fault propagation length to fault displacement is small; ii) the fault tip impinges upon a stratigraphic barrier which prevents further fault growth; continued displacement results in folding of beds ahead of the fault tip.
Return to Publications page