Mineralogy of volcanic rocks in Gusev Crater, Mars: Reconciling Mössbauer, Alpha Particle X-Ray Spectrometer, and Miniature Thermal Emission Spectrometer spectra

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Read Full Article (file size: 448071 bytes) Cited by JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, E06S04, doi:10.1029/2007JE002970, 2008 Mineralogy of volcanic rocks in Gusev Crater, Mars: Reconciling Mössbauer, Alpha Particle X-Ray Spectrometer, and Miniature Thermal Emission Spectrometer spectra H. Y. McSween Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee, USA S. W. Ruff Department of Geological Sciences, Arizona State University, Tempe, Arizona, USA R. V. Morris NASA Johnson Space Center, Houston, Texas, USA R. Gellert Department of Physics, University of Guelph, Guelph, Ontario, Canada G. Klingelhöfer Institut fur Anorganische und Analytische Chemie, Johannes Gutenberg-Universität, Mainz, Germany P. R. Christensen Department of Geological Sciences, Arizona State University, Tempe, Arizona, USA T. J. McCoy National Museum of Natural History, Smithsonian Institution, Washington, D. C., USA A. Ghosh Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee, USA J. M. Moersch Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee, USA B. A. Cohen NASA Marshall Space Flight Center, Huntsville, Alabama, USA A. D. Rogers Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA C. Schröder Institut fur Anorganische und Analytische Chemie, Johannes Gutenberg-Universität, Mainz, Germany S. W. Squyres Department of Astronomy, Cornell University, Ithaca, New York, USA J. Crisp Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA A. Yen Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA Abstract Complete sets of mineral abundances for relatively unaltered volcanic or volcaniclastic rocks in Gusev Crater have been determined by modeling Mössbauer subspectral areas as mineral weight percentages, and combining those percentages with the proportions of iron-free minerals not detected by Mössbauer (normative plagioclase, apatite, and chromite, as calculated from Alpha Particle X-Ray Spectrometer (APXS) chemical analyses). Comparisons of synthetic thermal emission spectra calculated for these mineral modes with measured Miniature Thermal Emission Spectrometer (Mini-TES) spectra for the same rock classes show either good agreements or discrepancies that we attribute to sodic plagioclase compositions or unmodeled sulfate, glass, or pigeonite. The normative compositions of olivine, pyroxene, and feldspar calculated from APXS data are consistent with spectroscopic constraints on mineral compositions. Systematic variations between olivine abundances in APXS norms (which sample tens of micrometers depth) and olivine proportions measured by Mössbauer (which sample hundreds of micrometers depth) support the hypothesis that dissolution of olivine by acidic fluids has occurred on weathered rock surfaces. Received 20 July 2007; accepted 23 January 2008; published 29 May 2008. Keywords: Mars; mineralogy; Gusev Crater. Index Terms: 3620 Mineralogy and Petrology: Mineral and crystal chemistry (1042); 3672 Mineralogy and Petrology: Planetary mineralogy and petrology (5410); 3694 Mineralogy and Petrology: Instruments and techniques; 5470 Planetary Sciences: Solid Surface Planets: Surface materials and properties. Read Full Article (file size: 448071 bytes) Cited by Citation: McSween, H. Y., et al. (2008), Mineralogy of volcanic rocks in Gusev Crater, Mars: Reconciling Mössbauer, Alpha Particle X-Ray Spectrometer, and Miniature Thermal Emission Spectrometer spectra, J. Geophys. Res., 113, E06S04, doi:10.1029/2007JE002970. Copyright 2008 by the American Geophysical Union.

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