Three-Dimensional Kinematics and Mechanics of Oblique Convergence and Divergence

9628381 Tikoff Major orogenic belts occur at zones of interaction between rigid plates or blocks which converse or diverge obliquely relative to one another. At zones of oblique convergence, material accommodates both shortening across the belt and lateral shearing parallel to the belt. In the upper crust this deformation is not accommodated homogeneously, with contraction structures having shortening directions perpendicular to the orogen coexisting with strike-slip faults oriented parallel to the belt. This phenomena of strike-slip partitioning occurs at subduction and continental collision zones on a variety of scales, but as yet does not have a clear mechanical explanation. The objective of this project is to test the hypothesis that strike-slip partitioning is inherently related to the nonplane-strain character of deformation in oblique tectonics. By combining kinematic modeling with a series of physical and numerical experiments, the dynamics of strike-slip partitioning will be investigated. Results are expected to improve the understanding of the fundamental mechanisms of strike-slip partitioning in the upper crust.