^1,2Tianqi Zhang,^1,3Qi Tao,^1,2Xiaorong Qin,^2,4Yuchun Wu,^1,2Jiaxin Xi,^1,3Xiaoliang Liang,^1,3Hongping He,⁵Sridhar Komarneni
Journal of Geophyical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2024JE008619]
¹State Key Laboratory of Deep Earth Processes and Resources, & Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, PR China
²University of Chinese Academy of Sciences, Beijing, PR China
³CAS Center for Excellence in Deep Earth Science, Guangzhou, PR China
⁴State Key Laboratory of Solar Activity and Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, PR China
⁵Department of Ecosystem Science and Management and Materials Research Institute, 204 Energy and the Environment Laboratory, The Pennsylvania State University, University Park, PA, USA
Published by arrangement with John Wiley & Sons

Despite the anticipated abundant carbonates due to historical atmospheric CO2 levels, Mars presents a geological puzzle with MgFe-smectites dominating the Noachian and early Hesperian terrains, contrasted by sparse carbonate deposits. To address this point, we explored the impact of CO2 on MgFe-smectite formation, emphasizing the role of variable Si concentrations within the simulated Martian environment. Hydrothermal experiments, conducted under a constant CO2 concentration (C0.5) and varying Si concentrations (Si0.5 to Si4), reveal a transformation from pyroaurite to MgFe-smectite via lizardite as an intermediary phase. This transformation underscores the crucial role of Si in this mineral sequence. Notably, experiments demonstrate that the interlayer CO32− in pyroaurite is released into aqueous environments during the mineral conversion, potentially impacting the Martian CO2 budget. These findings could explain isolated carbonate outcrops and the possibility of hydrotalcite-group minerals on Mars today. Further Mars exploration should consider identifying hydrotalcite-group minerals for their implications on the planet’s climate and habitability.