DISTRIBUTION ANISOTROPY - 2 SIMPLE-MODELS FOR MAGNETIC LINEATION AND FOLIATION

In a recent paper, Hargraves et al. (1991) have carried out experiments on synthetic samples containing magnetite particles distributed in layers. They show that anisotropy of susceptibility arises from such an arrangement and suggest that anisotropy in rocks may sometimes be a result of similar non-uniform distributions of interacting isotropic particles rather than to preferential orientation of anisotropic particles. In this paper two simple models involving either lines or planes of interacting spherical particles are used to show that non-uniform distributions of spherical particles can give rise to large anisotropies. Using the models, the separation between particles within a line (or plane) can be found directly from the measured anisotropy of susceptibility and if the average susceptibility is also measured, the separation between lines (or planes) of particles can also be determined in principle.