Hydrothermal origin of halogens at Home Plate, Gusev Crater

Mariek E. Schmidt, Steven Ruff, Timothy J. McCoy, William H. Farrand, Jeffrey R. Johnson, Ralf Gellert, Douglas W. Ming, Richard V. Morris, Nathalie Cabrol, Kevin W. Lewis, Christian Schroeder

Research output: Contribution to journalArticlepeer-review

64 Scopus citations

Abstract

In the Inner Basin of the Columbia Hills, Gusev Crater is Home Plate, an 80 m platform of layered elastic rocks of the Barnhill class with microscopic and macroscopic textures, including a bomb sag, suggestive of a phreatomagmatic origin. We present data acquired by the Spirit Mars Exploration Rover by Alpha Particle X-Ray Spectrometer (APXS), Mössbauer Spectrometer, Miniature Thermal Emission Spectrometer (Mini-TES), and Panoramic Camera (Pancam) for the Barnhill class rocks and nearby vesicular Irvine class basalts. In major element concentrations (e.g., SiO2, Al2O3, MgO, and FeO*), the two rock classes are similar, suggesting that they are derived from a similar magmatic source. The Barnhill class, however, has higher abundances of Cl, Br, Zn, and Ge with comparable SO3 to the Irvine basalts. Nanophase ferric oxide (np ox) and volcanic glass were detected in the Barnhill class rocks by Mössbauer and Mini-TES, respectively, and imply greater alteration and cooling rates in the Barnhill than in the Irvine class rocks. The high volatile elements in the Barnhill class agree with volcanic textures that imply interaction with a briny groundwater during eruption and (or) by later alteration. Differences in composition between the Barnhill and Irvine classes allow the fingerprinting of a Na-Mg-Zn-Ge-Cl-Br (±Fe ± Ca ± CO2) brine with low S. Nearby sulfate salt soils of fumarolic origin may reflect fractionation of an acidic S-rich vapor during boiling of a hydrothermal brine at depth. Persistent groundwater was likely present during and after the formation of Home Plate.

Original languageEnglish (US)
Article numberE06S12
JournalJournal of Geophysical Research: Planets
Volume113
Issue number6
DOIs
StatePublished - Jun 20 2008

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Geochemistry and Petrology
  • Geophysics
  • Oceanography
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science

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