A systematic analysis of natural magnetic mineral assemblages based on modelling hysteresis loops with coercivity-related hyperbolic basis functions

Abstract

SUMMARY The new rock-magnetic method presented here is a series of successive procedures, by which experimental hysteresis and back-field magnetization data are ultimately converted into ‘hyperbolic spectra’. The processing comprises smoothing and centring of raw data, asymptotic slope correction, determination of common hysteresis parameters and modelling of induced and remanent hysteresis components with specially adapted hyperbolic basis functions. The resulting spectral diagrams denote the relative contributions of 10-40 coercivity classes, each representing ferromagnetic particles of a narrow, clearly defined coercivity range. The distribution patterns of these spectra allow the discrimination and quantification of discrete mineral or grain-size fractions and the calculation of their partial hysteresis loops. A computer program (‘HYSTEAR’) for interactive and automated hysteresis loop data processing applying the algorithms described is available from the author.