The magnetic susceptibility anisotropy of deformed rocks from North Cornwall,England

The magnetic fabric of 306 samples from 51 sites was determined by means of a new, low-field anisotropy technique. The within-site consistency of the magnetic-fabric data was extremely high and was comparable with more tedious standard petrofabric analyses, where available, and with the structural properties of previously defined tectonic zones in North Cornwall. These data confirm the applicability of magnetic-fabric studies to structural problems, particularly in determining the orientation of the strain in the rocks. In areas of low strain, the technique appears applicable where standard petrofabric techniques are too coarse or time-consuming and indicates that direct estimates of both the magnitude and direction of the net strain ellipsoid should be possible in less deformed areas. Magnetic fabric studies therefore confirm the tectonic zonation in this region and provide a rapid method for similar structural evaluations.