Boudinage in homogeneous foliated rocks

Abstract

Theoretical and experimental studies confirm Platt and Vissers' suggestions that boudin-like structures in homogeneous foliated rocks can develop by deformation following fracture initiation. It is further shown that symmetrical foliation-boudins can develop only in coaxial deformation history with the foliation and the extension fracture remaining mutually perpendicular throughout the entire course of deformation. Asymmetric foliation boundinage may develop either in coaxial or in non-coaxial bulk deformation in the neighbourhood of short segments of fractures. The asymmetry can develop if either the foliation or the fracture or both are oblique to the principal axes of stress.