Paleomagnetism and rock-magnetism by Micro-Magnetic Tomography

Description du projet

La tomographie pionnière fournit des instantanés plus clairs du magnétisme changeant de la Terre

Le champ magnétique de la Terre forme une bulle protectrice qui protège notre planète des rayonnements du Soleil. Au fil des ans, des changements dans le champ magnétique terrestre ont été enregistrés par des minéraux riches en fer affectés par les influences magnétiques. Lorsque les minéraux sont piégés en place, ils sont comme des instantanés au moment du champ magnétique changeant de la Terre. Cependant, en présence de petites quantités de minéraux qui ne sont pas de bons enregistreurs, ces «instantanés» peuvent être flous. Avec la tomographie micromagnétique non destructive innovante, MIMATOM prévoit de zoomer sur des minéraux individuels plutôt que sur leur amas, fournissant ainsi une image plus claire des changements de champ magnétique au fil du temps. Cette connaissance nous permettra de prédire plus précisément l’avenir de notre bulle magnétique.

Objectif

Our knowledge on the past behavior of the Earth’s magnetic field critically depends on our ability to obtain and interpret magnetic signals from geological materials such as lavas. These materials contain mixtures of different magnetic minerals, some of which are good recorders of the Earth’s magnetic field, others are not. Even the presence of a small amount of minerals with adverse magnetic properties obscures the signal of good recorders, resulting in >80% of measurements of the past Earth’s magnetic field strength being flawed. Understanding the Earth’s magnetic field is pivotal for predicting the future of its shielding capacity against the Sun’s electromagnetically charged particles, which globally weakened by >20% over the last millennium.

With MIMATOM, I aim to establish an entirely new way to obtain paleomagnetic and rock-magnetic information from geological materials. I will go beyond measuring magnetizations of bulk samples by determining the magnetic moments of individual minerals embedded in these samples in a non-destructive way. Starting from my recent proof-of-concept of Micro-Magnetic Tomography (MMT), I will develop a radically new technique to assess magnetizations of individual minerals inside geological materials. This will enable understanding which minerals are reliable recorders of the Earth’s magnetic field by characterizing their magnetic behavior as function of their grain size, shape, and chemistry. Then I will use MMT to obtain paleomagnetic information from selections of minerals that I identified as good recorders and unlock information on the past state of the Earth’s magnetic field from even the most challenging and magnetically complex geological materials, such as lavas.

My revolutionary new technique will open archives of the past behavior of the Earth’s magnetic field that currently are inaccessible. Moreover, it will pave the way for radically new venues in paleomagnetic and rock-magnetic research, at mineral level.