Abstract

The mineralogical and elemental compositions of the martian soil are indicators of chemical and physical weathering processes. Using data from the Mars Exploration Rovers, we show that bright dust deposits on opposite sides of the planet are part of a global unit and not dominated by the composition of local rocks. Dark soil deposits at both sites have similar basaltic mineralogies, and could reflect either a global component or the general similarity in the compositions of the rocks from which they were derived. Increased levels of bromine are consistent with mobilization of soluble salts by thin films of liquid water, but the presence of olivine in analysed soil samples indicates that the extent of aqueous alteration of soils has been limited. Nickel abundances are enhanced at the immediate surface and indicate that the upper few millimetres of soil could contain up to one per cent meteoritic material.

1. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA
2. Max Planck Institut für Chemie,
3. Johannes Gutenberg University, D-55128 Mainz, Germany
4. NASA Johnson Space Center, Houston, Texas 77058, USA
5. Cornell University, Department of Astronomy, Ithaca, New York 14853, USA
6. Arizona State University, Department of Geological Sciences, Tempe, Arizona 85287, USA
7. Lockheed Martin Corporation, Littleton, Colorado 80127, USA
8. Washington University, Saint Louis, Missouri 63130, USA
9. NASA Ames Research Center, Moffett Field, California 94035, USA
10. Companhia Vale do Rio Doce, 29030-900 Rio de Janeiro, Brazil
11. Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA
12. Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996, USA
13. State University of New York, Department of Geosciences, Stony Brook, New York 11794, USA
14. US Geological Survey, Flagstaff, Arizona 86001, USA
15. Niels Bohr Institute, University of Copenhagen, DS-2100 Copenhagen, Denmark
16. DLR Institut für Raumsimulation, D-51170 Cologne, Germany

Correspondence to: Albert S. Yen¹ Correspondence and requests for materials should be addressed to A.Y. (Email: Albert.Yen@jpl.nasa.gov).

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