Susceptibility Anisotropy Measurements on some Silurian Siltstones

Abstract

ANISOTROPY of magnetic susceptibility, in certain sediments, is probably due to the preferred orientation of elongated magnetic grains. Rees¹ has shown that for varved silt redeposited in the laboratory the direction of the axis of maximum susceptibility is controlled initially by the geomagnetic field and in the final stages of deposition by water current and ‘compaction’ effects analogous to those which have been shown to affect the direction of remanent magnetization. This work reported here was undertaken to determine whether natural sediments also have an anisotropy which can be related to the direction of palæocurrent flow indicated by geological observations.