A Glimpse into Basalt Weathering on Mars: Geochemical Modeling Study of Lyot Crater

To reconstruct the past climate and assess the potential habitability of Mars, it is essential to understand its geological processes and environmental evolution. Till now, observations from orbital spectroscopy and in-situ rover missions have revealed the widespread presence of phyllosilicates, such as smectites, on the martian surface, indicating extensive past water-rock interactions and a prolonged aqueous history (Ehlmann & Edwards, 2014; Sheppard et al, 2021). Therefore, understanding basalt weathering processes is essential for constraining the formation history of these minerals and the climate evolution of Mars. However, given the limited direct access to Martian samples, geochemical modeling has become an essential tool for reconstructing these ancient processes. In our study, we apply such an approach to investigate basaltic weathering conditions and the formation of secondary alteration minerals within Lyot Crater, located in the northern lowlands of Mars. Lyot Crater formed during the Amazonian period and previous observations indicate the presence of significant amounts of Fe/Mg Phyllosilicates, chlorite, illite/ muscovite, prehnite and some other unidentified hydrated minerals within the region (Pan & Ehlmann, 2018). Because the Amazonian period is considered a dry phase in Martian history (Kolkas, 2026), investigating the origin of secondary minerals in Lyot Crater can provide important insights into the possibility of aqueous activity during this arid period.  To examine this, geochemical simulations were performed using the REACT Module of Geochemist’s Workbench (GWB) software, adopting initial basaltic rock compositions derived from in situ analyses at the Zhurong rover landing site (Zhao et al, 2023) and a groundwater composition representative of the Gale Crater region (Kikuchi & Shibuya, 2021). The simulations are performed under closed system condition, which means the system is unbuffered and does not remain in constant equilibrium with the atmosphere. The modeling results reproduce secondary mineral assemblages observed in Lyot Crater, supporting previously proposed hydrothermal formation scenarios for the region (Pan & Ehlmann, 2018). These results constrain Amazonian-age aqueous alteration processes and highlight Lyot Crater as a potential target for future habitability-focused exploration.

References:

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Kikuchi, S. and Shibuya, T., 2021. Minerals, 11(4), p.341.

Kolkas, M.M., 2026. The Professional Geologist (TPG), Jan–Feb–Mar, pp. 7–15.

Pan, L. and Ehlmann, B.L., 2018. Journal of Geophysical Research: Planets, 123(7), pp.1618-1648.

Sheppard, R.Y., Thorpe, M.T., Fraeman, A.A., Fox, V.K. and Milliken, R.E., 2021. Minerals, 11(9), p.986.

Zhao, Y.Y.S., Yu, J., Wei, G., Pan, L., Liu, X., Lin, Y., Liu, Y., Sun, C., Wang, X., Wang, J. and Xu, W., 2023. National Science Review, 10(6), p.nwad056.