1,2Xiaojia Zeng, 1,2Xiongyao Li
Geochimica et Cosmochimica Acta (in Press) Link to Article [DOI: 10.1016/j.gca.2026.10.025]
1State Key Laboratory of Critical Mineral Research and Exploration, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
2Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
Copyright Elsevier
Electrostatic discharge in Martian dust storms may significantly drive the chemical alteration and cycling of surface materials. Troilite is expected on Mars from magmatic and meteoritic sources but remains undetected by rovers, raising the question of possible electrostatic discharge-driven alteration. However, this hypothesis lacks direct experimental support. In this study, we experimentally simulate electrical discharge under Martian conditions by exposing troilite to such discharge in a CO2 atmosphere at low pressure. We found that electrical discharge rapidly oxidizes troilite to magnetite (Fe3O4), forming a ∼ 100 nm thick, polycrystalline, defect-rich alteration layer on the troilite surface. This oxidation is driven by reactive oxygen species attack Fe-S bonds, displace sulfur, and convert the residual iron framework into magnetite. Such an electrical discharge-driven pathway offers a new water-free mechanism for magnetite formation on Mars, specifically active during the hyper-arid Amazonian epoch. This work also provides an additional explanation for the missing troilite in Martian soils and the widespread occurrence of magnetite in Martian dust. More broadly, this study expands our understanding of Martian surface evolution beyond water-dominated scenarios and highlights oxidative role of ongoing dust activities on present-day Mars.
