A Preisach-based Model of Chemical Remanent Magnetisation Acquisition

Abstract:

Chemical remanent magnetisations (CRM) are ubiquitous in nature, but are usually ‘unwanted’ and their magnetic remanence signals are often discarded. There is a need for a better understanding of CRM growth and how it contributes to palaeointensity determination. Thermoremanence (TRM) acquisition has previously been successfully modelled using a thermally activated Preisach model and used to determine TRM palaeointensity estimates, without the need to heat samples. Here we use a similar approach to model grain-growth CRM. It is based on interacting single-domain grains, including a solution to the relaxation time equation accounting for the effect of growth rate on blocking volume. We use this model to explore how CRM intensity varies as a function of growth rate, how CRM compares to TRM, and to show how CRM contributes to palaeointensity determination in Thellier-type analysis.