Strain in sedimentary rocks is linked to deformation of underlying basement rocks during the formation of basement-involved folds. Strains are represented by an array of structures such as lift-off folds, thrust faults, heterogeneous thickness changes, extensional faults, and boudinage. Detachment surfaces define the boundaries of structural lithic units within sedimentary rocks that are characterized by different deformation styles.

A kinematic model is presented to investigate how strain distribution in folds is controlled by basement deformation. The model examines folds that form above a basement block that is displaced on a single reverse fault. Rocks in the fold undergo layer-parallel shortening (and thickening) and/or extension (and thinning). Extensional strains increase as fault angle and fault slip increase. As the basement fault propagates upsection strains will vary in the hanging wall and footwall of the fault and in unfaulted beds upsection from the fault tip. Results predicted by the modeling compare favorably with folds in the Rocky Mountain foreland province.