Analysis of three-dimensional strain modified uniform distributions: andalusite fabrics from a granite aureole

A method of analysing finite strain from an initial random distribution of lines or planes is presented. The shape of the strain ellipsoid is mapped to the eigenvalue ratios of an orientation matrix. The method is used to interpret the andalusite fabrics from the aureole of the Ardara granite, County Donegal, Ireland. The high flattening strains determined in the aureole are accompanied by oblate strains in the granite margins and support the concept of deformation produced by expansion of the pluton.