OPAQUE PETROLOGY AND STABILITY OF NATURAL REMANENT MAGNETISM IN BASALTIC ROCKS

The relationships between opaque petrological properties and stability of natural remanent magnetism have been examined using data from 514 basaltic specimens of tertiary‐quaternary and Carboniferous‐Devonian ages. Titanomagnetite deuteric (high temperature) oxidation state is found to be the dominant factor in controlling stability in both age groups. Titanomagnetite granulation—a low temperature alteration which we believe long postdates eruption—seems to influence stability only when unusually highly developed. Titanomagnetite overall grain size, as defined here, has little if any influence on stability over the size range in which the majority of specimens are found, even when only specimens in which titanomagnetite deuteric oxidation is absent are considered. Tests of the identity of natural remanence with original thermoremanence are discussed and it is concluded that this identity can often be demonstrated for Tertiary basaltic units and at least sometimes for older material. Copyright © 1969, Wiley Blackwell. All rights reserved