Estimating the Effect of Cooling Rate on the Acquisition of Magnetic Remanence

Abstract

The effect of cooling rate on the magnetization of rocks must be accounted for when estimating ancient magnetic field strengths. Calculating this effect is not trivial, even for uniformly magnetized grains. Here, we present an open-source package to compute the behavior of uniaxial single-domain grains for different temperature and magnetic fields. We revisit the problem of thermal remanence acquisition as a function of cooling rate and find that our predictions are broadly in agreement with those of Halgedahl et al. (1980, https://doi.org/10.1029/jb085ib07p03690) but differ significantly from those of Dodson and McClelland-Brown (1980, https://doi.org/10.1029/JB085iB05p02625). We also find that remanence acquisition curves correspond well with recent experimental observations. Cooling rate corrections made using our model are at the upper limit suggested by Halgedahl et al. (1980, https://doi.org/10.1029/jb085ib07p03690) but can reduce slightly for larger (single-domain) grains, very slow cooling rates of the original thermal remanence and large field strengths.