Abstract
AbstractThe 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.
Highlights
Recovering the strength of the Earth’s ancient magnetic field is a critical part of understanding our planet’s history
We briefly review the thermal theory of single domain remanence with particular reference to the implementation details in our C++ code
When Equation 10 is positive for any critical value θk, we have found a local energy minimum (LEM) state and the critical value is denoted θk,min
Summary
Previous efforts to estimate cooling rate effects result in different corrections. Our model agrees well with the model of Halgedahl et al (1980). The source code of our model is available for verification and further development. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record.
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