¹Alexander Rogaski,^1,2Gokce K. Ustunisik,³Shuying Yang,³Munir Humayun,⁴Kevin Righter,⁵Jeff A. Berger,⁶Nicholas DiFrancesco
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14000]
¹Department of Geology and Geological Engineering, South Dakota School of Mines and Technology, Rapid City, South Dakota, USA
²Department of Earth and Planetary Sciences, American Museum of Natural History, New York, New York, USA
³National High Magnetic Field Laboratory, Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, Florida, USA
⁴National Aeronautics and Space Administration, Lyndon B. Johnson Space Center, Houston, Texas, USA
⁵Jacobs JETSII, NASA Johnson Space Center, Houston, Texas, USA
⁶Department of Geology, University at Buffalo, Buffalo, New York, USA
Published by arrangement with John Wiley & Sons

The surface of Mars is enriched in Cl and S which is linked to volcanic activity and degassing. Similarly, elevated Ge and Zn levels in Gale crater sedimentary bedrock indicate a magmatic source for these elements. To constrain the relative effects of Cl and S on the outgassing of these trace metals and chemical characteristics of primary magmatic vapor deposits incorporated to Martian surface, we conducted a set of degassing and fumarolic alteration experiments. Ge is found to be more volatile than Zn in all experiments. In S-bearing runs, the loss of Ge and Zn was less than any other experiments. In Cl-only runs, degassing of Zn was more than twice that of Ge within the first 10 min and percent loss increased for both elements with increasing time. In Cl + S runs, S-induced reduction of GeO2 and ZnO to metallic Ge and Zn switches the preference of chloride formation from Zn to Ge. Up to 90% of Ge and Zn loss in the 1-h no volatile-added (NVA) experiments might be due to the small amounts of Cl contamination in NVA mixes via other oxides used for synthesis. Alteration experiments show different phases between 1-h and 24-/72-h runs. In 1-h runs, anhydrite and langbeinite dominate while in 24-/72-h runs halite and sylvite dominate the condensate assemblages. S-bearing phases form as the intermediate products of fumarolic deposition, while chlorides are common when the system is allowed to cool gradually. One-hour exposure was sufficient to form alteration phases and vapor deposits such as NaCl, KCl, CaSO4, and langbeinites on the Martian analog minerals. These salts were identified in Martian meteorites and in situ measurements. Our results provide evidence that volcanic degassing along with fumarolic alteration could be a potential source for the enrichment and varying abundances of Cl, S, Fe, Zn, Ge in Martian surface, as well as a cause for Ge depletion in shergottites.