Outcrop-scale tomography: Insights into the 3D structure of multiphase boudins

Results show five generations of brittle extension of the amphibolite in ductile marble, although examination of the boudinaged layer on the outside of the block only suggested one generation. Most prominent are the rotated domino boudins, where part of the dilatancy between domino boudins can be shown to be due to later reactivation. Shear fractures between domino boudins have relatively large throw gradients, indicating ductile rupture. Layer-parallel stretch as measured by reconstruction of domino boudins decreases with amphibolite layer thickness although the layer has undergone the same bulk stretch everywhere. This suggests that with decreasing layer thickness deformation becomes delocalized, offering tantalizing glimpses of rheology under metamorphic conditions.