Published August 2024 | Published
Journal Article Open

Gypsum on Mars: A Detailed View at Gale Crater

  • 1. ROR icon Planetary Science Institute
  • 2. ROR icon Johnson Space Center
  • 3. ROR icon Ames Research Center
  • 4. ROR icon Research Institute in Astrophysics and Planetology
  • 5. ROR icon University of Arizona
  • 6. ROR icon Carnegie Mellon University
  • 7. ROR icon Lunar and Planetary Institute
  • 8. ROR icon Jet Propulsion Lab
  • 9. ROR icon Goddard Space Flight Center
  • 10. ROR icon University of Calgary
  • 11. ROR icon University of Nevada, Las Vegas
  • 12. ROR icon California Institute of Technology

Abstract

Gypsum is a common mineral at Gale crater on Mars, currently being explored by the Mars Science Laboratory (MSL) rover, Curiosity. In this paper, we summarize the associations of gypsum with other sulfate minerals (bassanite, anhydrite, jarosite, starkeyite, and kieserite) from the lowest levels of the crater's northern moat zone (Aeolis Palus) up through ~0.8 km of the stratigraphic section in the lower slopes of the sedimentary mound developed around the central peak, Aeolis Mons (informally, Mount Sharp). The analysis is based on results from the CheMin X-ray diffraction instrument on Curiosity, supplemented with information from the rover's versatile instrument suite. Gypsum does not occur with the same frequency as less hydrous Ca-sulfates, likely, in most cases, because of its dehydration to bassanite and possibly to anhydrite. All three of these Ca-sulfate phases often occur together and, along with other sulfates, in mixed assemblages that are evidence of limited equilibration on a cold, dry planet. In almost all samples, at least one of the Ca-sulfate minerals is present, except for a very limited interval where jarosite is the major sulfate mineral, with the implication of more acidic groundwater at a much later time in Gale crater's history. Although observations from orbit reveal a sulfate-rich surface, currently active dark basaltic dunes at Gale crater have only small amounts of a single sulfate mineral, anhydrite. Gale crater has provided the most complete mineralogical analysis of a site on Mars so far, but the data in hand show that Gale crater mineralogy is not a blueprint with planet-wide application. The concurrent study of Jezero crater by the Mars 2020 mission and comparisons to what is believed to be the most extensive deposit of gypsum on Mars, in the dune fields at the north polar ice cap, show significant diversity. Unraveling the stories of gypsum and other sulfates on Mars is just beginning.

Copyright and License

© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Acknowledgement

The authors are grateful to Suniti Karunatillake of Louisiana State University for discussions of the 2001 Mars Odyssey mission orbital gamma ray spectrometer (GRS) data shown in Figure 1. We would also like to acknowledge the very helpful corrections and suggestions offered by three anonymous reviewers.

Funding

Funding for this work came from NASA’s Mars Exploration Program through the Mars Science Laboratory project via the contributors’ respective instrument PIs and the MSL Participating Scientist Program. A portion of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004).

Contributions

Investigation, all authors; methodology, D.V., S.C., E.R., T.B., D.B., J.M., T.P., D.M., P.C., N.C., R.T.D., S.M., R.H., R.M., A.P., A.H.T., A.Y., C.A., B.T., E.H., S.S., M.T., V.T., D.J.D.M. and J.G.; data collection, D.V., S.C., E.R., T.B., D.B., J.M., W.R., J.B., D.M., P.C., N.C., R.T.D., S.M., R.H., R.M., A.P., A.H.T., A.Y., C.A., B.T., E.H., S.S., M.T., V.T. and D.J.D.M.; data analysis, D.V., S.C., E.R., T.B., D.B., J.M., T.P., W.R., J.B., D.M., P.C., N.C., R.T.D., S.M., R.H., R.M., A.P., A.H.T., A.Y., C.A., B.T., E.H., S.S., M.T., V.T. and D.J.D.M.; figure production, D.V., W.R., J.B. and A.F.; writing—original draft preparation, D.V.; management, T.B., E.R. and A.F. All authors have read and agreed to the published version of the manuscript.

Data Availability

Publicly available datasets were analyzed in this study. These data can be found here: https://pds.nasa.gov, accessed on 26 June 2024. Additional contextual information can be found in the publicly available Gale crater Mineralogy and Geochemistry Sample Database found here: https://doi.org/10.48484/JN48-YW52 (accessed on 20 June 2024) and the CheMin Database (https://odr.io/CheMin#/search/display/84/eyJkdF9pZCI6IjQzIn0/1 (accessed on 20 June 2024).

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Additional details

Created:
January 23, 2025
Modified:
January 23, 2025