The Variation of Magnetic Properties among Red Sandstones

Abstract

Magnetic properties of samples from thirteen formations of red sandstones have been measured, together with their ferrous and ferric iron and titanium content. Initial susceptibility, induced magnetization and isothermal remanent magnetization per unit mass of rock correlate generally with ferric iron content; the magnitude of these properties per unit mass of contained ferric oxide often show considerable scatter, however, both within one formation and in the mean values for each formation. This scatter is believed to be due to varying proportions of pigment and speculante in the rocks and to the presence of a mineral containing ferrous iron, tentatively identified as a titanohaematite. The palaeomagnetic characteristics of the sandstones, such as magnetic stability or instability and the existence of reversals, do not appear to be reflected in the magnetic properties of the contained minerals.