The role of serpentinization in magnetizing the Noachian crust of Mars

Presence of a remnant crustal magnetic field and its spatial relationship to large impact basins indicates that Mars had a global dynamo during the Noachian eon (>4 Ga) (1-4). The geological processes responsible for the magnetization of the Martian crust, however, remain enigmatic. A plethora of morphological and compositional evidence suggests that high-temperature water-rock reaction was pervasive during the Noachian eon. Here we show that chemical rema-nent magnetization associated with serpentinization was possibly a key contributor to Mars’ crustal magnetic field. The conditions in the Martian subsurface during the Noachian eon were conducive to serpentinization, as we show through numerical models of hy-drothermal circulation. Geological features on Mars that implicate water-rock reaction statistically significantly align with areas showing a notably higher crustal magnetic field intensity than the average Noachian terrain. The spatial association of highest crustal magnetic field anomalies with areas of elevated heat-producing element concentrations further bolsters the likelihood of hydrothermal circulation sustained over geologic time. Such Noachian conditions would not only enable pervasive serpentinization of the mafic Martian crust but also release climate-transforming potent greenhouse gases such as H 2 and CH 4 while supporting a subsurface habitable environment.