A thermodynamical model for paleomagnetism in Earth's crust

TL;DR

This paper develops a thermodynamically consistent model for paleomagnetism in Earth's crust, incorporating phase transitions, rheology, and energy balance to better understand magnetic properties of rocks during geological processes.

Contribution

It introduces a novel thermodynamical model for soft deformable viscoelastic magnets, including phase transitions and rheological behaviors relevant to paleomagnetism.

Findings

Model demonstrates thermodynamic consistency and energy balance.

Existence of weak solutions proven through time discretization.

Applicable to understanding rock-magma magnetic transitions.

Abstract

A thermodynamically consistent model for soft deformable viscoelastic magnets is formulated in actual space (Eulerian) coordinates. The possibility of a ferro-paramagnetic-type (or ferri-antiferromagnetic) transition exploiting Landau phase transition theory as well as mechanical melting or solidification is considered, being motivated and applicable to paleomagnetism (involving both thermo- and isothermal and viscous remanent magnetization) in rocks in Earth's crust and to rock-magma transition. The temperature-dependent Jeffreys rheology in the deviatoric part combined with the Kelvin-Voigt rheology in the spherical (volumetric) part is used. The energy balance and the entropy imbalance behind the model are demonstrated, and its analysis is performed by time discretization, proving existence of weak solutions.