CaltechAUTHORS
Published July 1, 2018 | Version public
Journal Article Metadata-only

Gypsum, bassanite, and anhydrite at Gale crater, Mars

Creators

  • 1. ROR icon Planetary Science Institute
  • 2. ROR icon University of Michigan–Ann Arbor
  • 3. ROR icon Johnson Space Center
  • 4. ROR icon Ames Research Center
  • 5. ROR icon Jet Propulsion Lab
  • 6. ROR icon California Institute of Technology
  • 7. ROR icon Research Institute in Astrophysics and Planetology
  • 8. ROR icon University of Arizona
  • 9. ROR icon Lunar and Planetary Institute
  • 10. ROR icon Brown University
  • 11. ROR icon Los Alamos National Laboratory
  • 12. ROR icon University of California, Davis

Abstract

Analyses by the CheMin X-ray diffraction instrument on Mars Science Laboratory show that gypsum, bassanite, and anhydrite are common minerals at Gale crater. Warm conditions (∼6 to 30 °C) within CheMin drive gypsum dehydration to bassanite; measured surface temperatures and modeled temperature depth profiles indicate that near-equatorial warm-season surface heating can also cause gypsum dehydration to bassanite. By accounting for instrumental dehydration effects we are able to quantify the in situ abundances of Ca-sulfate phases in sedimentary rocks and in eolian sands at Gale crater. All three Ca-sulfate minerals occur together in some sedimentary rocks and their abundances and associations vary stratigraphically. Several Ca-sulfate diagenetic events are indicated. Salinity-driven anhydrite precipitation at temperatures below ∼50 °C may be supported by co-occurrence of more soluble salts. An alternative pathway to anhydrite via dehydration might be possible, but if so would likely be limited to warmer near-equatorial dark eolian sands that presently contain only anhydrite. The polyphase Ca-sulfate associations at Gale crater reflect limited opportunities for equilibration, and they presage mixed salt associations anticipated in higher strata that are more sulfate-rich and may mark local or global environmental change. Mineral transformations within CheMin also provide a better understanding of changes that might occur in samples returned from Mars.

Additional Information

© 2018 Mineralogical Society of America. Manuscript received October 24, 2017; Manuscript accepted March 21, 2018. This paper was improved with helpful reviews by Ron Peterson and Melissa Lane. Support from the NASA Mars Science Laboratory Mission for CheMin development and operation is gratefully acknowledged. Sulfate stability work by D.T.V. and S.J.C. was supported through Los Alamos National Laboratory Directed Research and Development funding, and NASA grant NNH10A083I.

Additional details

Identifiers

Eprint ID
87511
Resolver ID
CaltechAUTHORS:20180702-095800652

Funding

Los Alamos National Laboratory
NASA
NNH10A083I

Dates

Created
2018-07-03
Created from EPrint's datestamp field
Updated
2021-11-15
Created from EPrint's last_modified field

Caltech Custom Metadata

Caltech groups
Division of Geological and Planetary Sciences (GPS)