Magnetic Remanence Coercivity of Rocks

Abstract

An anomalously large value of the ratio of remanence coercive force (HRC) to coercive force (Hc) (i.e. HRC/HC) which is much beyond a range of HRC/HC for a single phase magnetic mineral, is often found in natural rocks, particularly in extraterrestrial rocks. The observed large values of HRC/HC are interpreted as mostly due to the coexistence of a high coercivity component (a) and a low coercivity component (b). In a binary system of high and low coercivity components, HRC is largely controlled by the high coercivity component and Hc largely by the low coercivity component in accordance with definitions of HRC and HC, respectively. A simple model of such a magnetic binary system for purposes of estimating the magnetic coercivities of both components from the observed bulk values of HRC, HC and IR/IS is proposed, where IR and IS respectively denote saturation remanence and saturation magnetization. It is shown that the proposed model well approximates experimental data with an uncertainty of less than a factor of 2. © 1987, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.