Vertical axis rotations (with respect to original or regional orientations) of blocks of rock have been defined adjacent to major strike-slip faults. Kinematic models for these rotations have been proposed, and they require knowledge of the size of the blocks that behave rigidly and the spatial and temporal distributions of rotations. However available data do not allow testing between the various models. This project will examine paleomagnetically determined rotations adjacent to the Las Vegas Valley Shear Zone and the Lake Mead Fault System. The rocks yield stable primary directions and show large rotations. Dense sampling will constrain the size of blocks and their distribution with respect to the faults. Results should help resolve competing kinematic models for vertical axis rotations and permit the development of physical models describing fundamental processes during crustal deformation.
