Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Golden, D.C. Articles by Graff, T.G. Search for Related Content GeoRef GeoRef Citation

Hydrothermal synthesis of hematite spherules and jarosite: Implications for diagenesis and hematite spherule formation in sulfate outcrops at Meridiani Planum, Mars

¹ ESCG-Hamilton Sundstrand, Mail Code JE23, Houston, Texas 77058, U.S.A.
² Astromaterials Research and Exploration Science Directorate, NASA Johnson Space Center, Houston, Texas 77058, U.S.A.
³ School of Earth and Space Exploration, Mars Spaceflight Facility, Arizona State University, Tempe, Arizona, 85287-6305, U.S.A.

Correspondence: ^* E-mail: douglas.w.ming{at}nasa.gov

We synthesized hematite spherules whose mineralogic, chemical, and crystallographic properties are strikingly similar to those for the hematite-rich spherules in lag deposits on the surface and embedded in outcrops at Meridiani Planum, Mars. The spherules were synthesized in the laboratory along with hydronium jarosite and minor hydronium alunite from Fe-Al-Mg-S-Cl acid-sulfate solutions under hydrothermal conditions. The reaction sequence was (1) precipitation of hydronium jarosite; (2) jarosite dissolution and precipitation of hematite spherules; and (3) precipitation of hydronium alunite upon depletion of hydronium jarosite. The spherules exhibit a radial growth texture with the crystallographic c axis aligned along the radial direction, so that thermal emission spectra have no hematite emissivity minimum at ~390 cm^–1. Our experiments show that hydrothermal, acid-sulfate solutions are a pathway for formation of jarosite and the hematite spherules at Meridiani Planum, Mars.

Key Words: Hematite • jarosite • spherule • synthesis • diagenesis • Mars • hydrothermal • concretions • thermal emission spectroscopy • X-ray diffraction • Mössbauer spectroscopy • scanning electron microscopy • transmission electron microscopy

This article has been cited by other articles:

				M. E. Elwood Madden, A. S. Madden, and J. D. Rimstidt How long was Meridiani Planum wet? Applying a jarosite stopwatch to determine the duration of aqueous diagenesis Geology, July 1, 2009; 37(7): 635 - 638. [Abstract] [Full Text] [PDF]