¹C.J.Renggli,¹S.Klemme,²A.Morlok,¹J.Berndt,²I.Weber,²H.Hiesinger,³P.L.King
Earth and Planetary Science Letters 593, 117647 Link to Article [https://doi.org/10.1016/j.epsl.2022.117647]
¹Institut für Mineralogie, Westfälische Wilhelms-Universität Münster, Münster, 48149, Germany
²Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Münster, 48149, Germany
³Research School of Earth Sciences, The Australian National University, Canberra, 2601, Australia
Copyright Elsevier

The surface of Mercury is enriched in sulfur, with up to 4 wt.% detected by the NASA MESSENGER mission, and has been challenging to understand in the context of other terrestrial planets. We posit, that magmatic S was mobilized as a gas phase in volcanic and impact processes near the surface, exposing silicates to a hot S-rich gas at reducing conditions and allowing conditions for rapid gas-solid reactions. Here, we present novel experiments on the reaction of Mercury composition glasses with reduced S-rich gas, forming Ca- and Mg-sulfides. The reaction products provide porous and fragile materials that create previously enigmatic hollows on Mercury. Our model predicts that the gas-solid reaction forms Ca-Mg-Fe-Ti-sulfide assemblages with SiO2 and aluminosilicates, distinct from formation as magmatic minerals. The ESA/JAXA BepiColombo mission to Mercury will allow this hypothesis to be tested.