Spectral, mineralogical, and geochemical variations across Home Plate, Gusev Crater, Mars indicate high and low temperature alteration

Creators: Schmidt, M. E.; Farrand, W. H.; Johnson, J. R.; Schröder, C.; Hurowitz, J. A.; McCoy, T. J.; Ruff, S. W.; Arvidson, R. E.; Des Marais, D. J.; Lewis, K. W.; Ming, D. W.; Squyres, S. W.; de Souza, P. A., Jr.

Abstract

Over the last ~ 3 years in Gusev Crater, Mars, the Spirit rover observed coherent variations in color, mineralogy, and geochemistry across Home Plate, an ~ 80 m-diameter outcrop of basaltic tephra. Observations of Home Plate from orbit and from the summit of Husband Hill reveal clear differences in visible/near-infrared (VNIR) colors between its eastern and western regions that are consistent with mineralogical compositions indicated by Mössbauer spectrometer (MB) and by Miniature Thermal Emission Spectrometer (Mini-TES). Pyroxene and magnetite dominate the east side, while olivine, nanophase Fe oxide (npOx) and glass are more abundant on the western side. Alpha Particle X-Ray Spectrometer (APXS) observations reveal that eastern Home Plate has higher Si/Mg, Al, Zn, Ni, and K, while Cl and Br are higher in the west. We propose that these variations are the result of two distinct alteration regimes that may or may not be temporally related: a localized, higher temperature recrystallization and alteration of the east side of Home Plate and lower temperature alteration of the western side that produced npOx.

Additional Information

© 2009 Elsevier B.V. Received 16 October 2008; revised 20 February 2009; accepted 23 February 2009. Editor: R.W. Carlson. Available online 26 March 2009. Funding for Athena science team members was provided by NASA Mars Exploration Rover mission contracts through the Jet Propulsion Laboratory. This manuscript was improved by reviews on a previous version by Joshua Bandfield and two anonymous reviewers and three anonymous reviewers on the current incarnation. We thank the HiRISE team for making their high quality images of Mars available to the scientific community. And we especially thank the team of scientists and engineers who have made and who continue to make Mars Rover science so successful.

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