Is it possible to infer the magnetic field strength of the early solar system from meteorites?

What is it about?

Our understanding of the evolution of the magnetic fields of planets largely relies on the study of the magnetization, which is stored in magnetic particles of meteorites. Meteorites are among the oldest objects in the solar system. They have been ejected by an impact from their host planet into space. Therefore, most meteorites have been shocked to some degree (shock stages). We use specialized experiments to recover the magnetic field strength (paleointensity) from these meteorites. It is well known that both compression and decompression alter the remanence state of a rock, yet no one ever quantified the effect on paleointensity recording. We are the first to study the influence of static, hydrostatic and uniaxial pressure on the recovery of magnetic field information from rock samples. We find a decreasing magnetization of the sample when pressure is applied that leads to a underestimated paleointensity. The influence of pressure (-10% / GPa) in the hydrostatic case is low compared to other uncertainties. This leads to the conclusion that paleointensities, which are derived from stressed materials, should only be taken as lower limits.

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Why is it important?

Our understanding of how planets evolve to have magnetic fields relies on measurements of the magnetic properties of meteorites. Magnetic properties are known to be influenced by pressure. Furthermore, we know that remanent magnetization can be removed by applying force on a rock. In this study, we have provided an experimental basis for the validity of paleointensities derived from meteorites.

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