Martian Crustal Anomalies

While Mars no longer has a dynamo today, one of the strongest sources of evidence that Martian was once able to internally generate a magnetic field is the presence of crustal magnetic anomalies. Interestingly, the crustal remanence on Mars is roughly one order of magnitude larger than that found on Earth, and the reason why is uncertain. Some authors suggest that the dynamo was 10x stronger than Earth, while other propose that there is a larger abundance of magnetic minerals. One way to produce magnetic minerals is through aqueous alteration, which may have been relevant to an early Mars that hosted water. 

Early Mars was likely a warmer and wetter place than what we see today. Liquid water flowing on the surface would have reacted with the minerals in rocks, releasing cations and forming new minerals. Indeed, we see evidence of water-rock interactions from rover data. Unlike Earth, which has a oxygen-rich atmosphere, it is thought that early Mars might have been anoxic. In that case, how can magnetic minerals, which often have oxidized iron in their structure, form? One way is though water-rock interactions, in which iron cations released through mineral dissolution oxidizes through the oxygen in water. Interestingly, a byproduct of such a reaction is hydrogen gas, which might have helped keep Mars warm and provide an atmosphere for life to form. In this ongoing project, we are altering olivine powder in water under a range of anoxic conditions, such as at different pH values, and determining what situations lead to magnetic mineral production. Check back soon for updates!