A Discussion on natural strain and geological structure - Magnetic, seismic, and other anisotropic properties of rock fabrics

Abstract

Magnetic fabric, as a resultant property, summed over individual grains in a rock, stands apart from other, bulk property measurements (e.g. seismic, thermal, dielectric anisotropy), which treat the rock as a continuum. Thus, magnetic anisotropy can be more directly related to preferred orientation of grains in a rock than can bulk property measurements. The latter, however, may permit remote, geophysical determinations of large scale 'fabric' features. These contrasting aspects of fabric determination are discussed, drawing examples of magnetic fabric analysis from studies on naturally and experimentally deformed rocks, and seismic anisotropy from refraction studies of the crust and upper mantle.