Concentration of H, Si, Cl, K, Fe, and Th in the low- and mid-latitude regions of Mars

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Read Full Article (file size: 903178 bytes) Cited by JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, E12S99, doi:10.1029/2007JE002887, 2007 Concentration of H, Si, Cl, K, Fe, and Th in the low- and mid-latitude regions of Mars W. V. Boynton Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA G. J. Taylor Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawaii, USA L. G. Evans Science Programs, Computer Sciences Corporation, Lanham, Maryland, USA R. C. Reedy Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, USA R. Starr Department of Physics, Catholic University of America, Washington, D. C., USA D. M. Janes Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA K. E. Kerry Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA D. M. Drake TechSource, Santa Fe, New Mexico, USA K. J. Kim Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, USA R. M. S. Williams Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA M. K. Crombie Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA J. M. Dohm Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona, USA V. Baker Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona, USA A. E. Metzger Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA S. Karunatillake Center for Radiophysics and Space Research, Cornell University, Ithaca, New York, USA J. M. Keller Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA H. E. Newsom Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, USA J. R. Arnold Department of Chemistry, University of California, San Diego, La Jolla, California, USA J. Brückner Max-Planck-Institut für Chemie, Mainz, Germany P. A. J. Englert Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawaii, USA O. Gasnault Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, Toulouse, France A. L. Sprague Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA I. Mitrofanov Space Research Institute (IKI), Moscow, Russia S. W. Squyres Center for Radiophysics and Space Research, Cornell University, Ithaca, New York, USA J. I. Trombka NASA Goddard Space Flight Center, Greenbelt, Maryland, USA L. d'Uston Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, Toulouse, France H. Wänke Max-Planck-Institut für Chemie, Mainz, Germany D. K. Hamara Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA Abstract We report maps of the concentrations of H, Si, Cl, K, Fe, and Th as determined by the Gamma Ray Spectrometer (GRS) on board the 2001 Mars Odyssey Mission for ±∼45° latitudes. The procedures by which the spectra are processed to yield quantitative concentrations are described in detail. The concentrations of elements determined over the locations of the various Mars landers generally agree well with the lander values except for Fe, although the mean of the GRS Fe data agrees well with that of Martian meteorites. The water-equivalent concentration of hydrogen by mass varies from about 1.5% to 7.5% (by mass) with the most enriched areas being near Apollinaris Patera and Arabia Terra. Cl shows a distribution similar to H over the surface except that the Cl content over Medusae Fossae is much greater than elsewhere. The map of Fe shows enrichment in the northern lowlands versus the southern highlands. Silicon shows only very modest variation over the surface with mass fractions ranging from 19% to 22% over most of the planet, though a significant depletion in Si is noted in a region west of Tharsis Montes and Olympus Mons where the Si content is as low as 18%. K and Th show a very similar pattern with depletions associated with young volcanic deposits and enrichments associated with the TES Surface Type-2 material. It is noted that there appears to be no evidence of significant globally distributed thick dust deposits of uniform composition. Received 5 January 2007; accepted 2 August 2007; published 21 December 2007. Keywords: Mars; gamma-ray; elements. Index Terms: 6225 Planetary Sciences: Solar System Objects: Mars; 7554 Solar Physics, Astrophysics, and Astronomy: X-rays, gamma rays, and neutrinos; 1065 Geochemistry: Major and trace element geochemistry; 5410 Planetary Sciences: Solid Surface Planets: Composition (1060, 3672); 5464 Planetary Sciences: Solid Surface Planets: Remote sensing. Read Full Article (file size: 903178 bytes) Cited by Citation: Boynton, W. V., et al. (2007), Concentration of H, Si, Cl, K, Fe, and Th in the low- and mid-latitude regions of Mars, J. Geophys. Res., 112, E12S99, doi:10.1029/2007JE002887. Copyright 2007 by the American Geophysical Union.

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