This thesis investigates the relationship between impacts and meteorite palaeomagnetism. Using numerical modelling techniques, laboratory shock physics experiments and magnetic measurements, this work finds impact events capable of both recording and erasing meteorite magnetisations, storing the magnetisation of multiple ancient palaeofields at different times as well as controlling the magnetic domain state on the grain-scale.

Chondritic meteorites (chondrites) are among the most primitive meteorites in the Solar System, show no sign of high-temperature melting, but are often found to host a thermoremanence, recorded during their formation around 4.5 billion years ago. Their unmelted and 'unshocked' nature has previously disregarded impacts as significant factors in their evolution. However, recent studies have suggested that low-velocity impacts on the highly-porous chondrite parent bodies lead to the recording of thermoremanences. This mechanism has been developed theoretically and tested numerically, but never tested in the laboratory. It is one of the major goals of my PhD thesis to experimentally test this theory.

Beyond primitive chondrites, another major goal of this thesis is to demonstrate the importance of impacts as a palaeomagnetic recording mechanism, source of demagnetisation and how the magnetisation is able to inform about past impact events. I have modelled the shock-response of a Martian meteorite to understand how multiple palaeomagnetic signatures may be recorded in a single meteorite. Results show highly-localised shear heating heated a fraction of the magnetic carriers present in each impact, recording partial-thermoremanences at different times. Using micromagnetic modelling, the affect of stress on the remanence state of magnetite in the absence of any heating or an external magnetic field has also been explored. The results suggest many meteorites have likely had their remanences altered since recording, even in very weak, 'cold' impacts, <0.1 GPa.