Relationship between concentric longitudinal strain and concentric shearing strain during folding of homogeneous sheets of rocks

Abstract

For folds with a small amplitude/wave length ratio in homogeneous, isotropic, Newtonian media, concentric shearing strain in the flanks is related to the maximum concentric longitudinal strain through the layer thickness and arc length per wave. Unless thickness is greater than one third of the arc length, diagonal shearing strain in the crests is greater than the maximum concentric shearing strain in the flanks, and diagonal slips and fractures would therefore tend to develop in the crests before concentric slippage in the flanks.