Simple hysteresis loop model for rock magnetic analysis

A simple phenomenological model founded on Lorentzian functions is evaluated on the first derivative of magnetic hysteresis loops from several artificial samples with iron oxide/oxyhydroxide mixtures imitating natural sediments. The approach, which shows that hysteresis loops can be described by elementary analytical functions and provides estimates of magnetization parameters to a satisfactory degree of confidence, is applied with the help of standard data analysis software. Distorted hysteresis loops (wasp-waisted, goose-necked and pot-bellied shaped) from simulations and artificial samples from a previous work are reproduced by the model which allows to straightforwardly unmix the ferromagnetic signal from different minerals like magnetite, greigite, haematite and goethite. The analyses reveal that the contribution from the ferrimagnetic fraction, though present in a minor concentration (≤2.15 wt%), dominates the magnetization.