PhD defence: Micromagnetic Tomography: Insights from a single Hawaiian basalt

Paleomagnetism is the art of retrieving the direction and intensity of the Earth Magnetic Field from rock samples of varying ages and locations. This data can be used for a wide variety of Earth Scientific purposes, from reconstructing plate tectonics to modeling the geodynamo. Classic paleomagnetic experiments generally consist of replacing the natural remanent magnetization of a bulk (1 inch3) sample with a lab-induced remanent magnetization. These experiments sometimes give puzzling, inconsistent, or no results at all, which can be frustrating when samples are physically scarce, or unique in age or location. 

In bulk measurements, grains with good recording properties can be obscured by grains with bad recording properties. Micromagnetic Tomography (MMT) is a newly developed technique to retrieve the magnetic signal from individual magnetic grains using a Quantum Diamond Microscope (QDM). Reconstructing paleomagnetic data from individual grains is the next step in retrieving paleomagnetic data from samples that do not give results in bulk protocols. 

This thesis can be used as a reference and inspiration for designing MMT experiments. It contains an extensive explanation of the physics that lead to MMT results and details of all the methods applied in this thesis. I advance MMT by applying it to a Hawaiian basaltic sample that has previously been studied chemically, mineralogically and paleomagnetically. Over the course of 5 years I have done close to 100 MMT scans of a single 3 mm microcore. It is amazing how much insight we have gained from this single tiny sample.