| Abstract: | Mechanically passive features with structural polarity such as faint graded beds or cross beds are apt to be the best natural gauges of two-dimensional paleo-rotation. If the primary dip direction of cross bedding is known, then the planes of bedding and cross bedding collectively record the magnitude of three-dimensional rotation. Rigid spherical inclusions fail to roll as a result of oblique superposition of pure finite strains or due to bulk rotation of lithologic units. In progressive simple shear, the rigid-body rotation of spherical or circular inclusions is generally greater than the solid-body rotation of the weak matrix, which cannot exceed 90 degrees. |
