Variations in K/Th on Mars

G. Jeffrey Taylor, J. D. Stopar, William V. Boynton, S. Karunatillake, John M. Keller, J. Brückner, H. Wänke, G. Dreibus, Kris E. Kerry, Robert C. Reedy, Larry G. Evans, Richard D. Starr, L. M V Martel, S. W. Squyres, O. Gasnault, S. Maurice, C. d'Uston, P. Englert, J. M. Dohm, Victor BakerD. Hamara, Daniel M. Janes, Ann L. Sprague, Kyeong J. Kim, D. M. Drake, S. M. McLennan, B. C. Hahn

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50 Scopus citations


K/Th determined by the Mars Odyssey Gamma Ray Spectrometer varies by a factor of 3 on Mars (3000 to 9000), but over 95% of the surface area has K/Th between 4000 and 7000. K/Th is distinctly lower than average in some areas, including west of Olympus Mons in the Amazonis Planitia, the region around Memnonia Fossae, Chryse Planitia, southeastern Arabia Terra, Syrtis Major Planum, and northwest of Apollinaris Patera. On the other hand, K/Th is distinctly higher than average in other areas, including the central part of Valles Marineris and the surrounding highlands, and in the northern part of Hellas. The generally modest variation in K/Th may be explained by inherent variations in igneous rocks and by variations in the extent of aqueous alteration.

Original languageEnglish (US)
Article numberE03S06
JournalJournal of Geophysical Research: Space Physics
Issue number3
Publication statusPublished - Mar 20 2007


ASJC Scopus subject areas

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

Cite this

Taylor, G. J., Stopar, J. D., Boynton, W. V., Karunatillake, S., Keller, J. M., Brückner, J., ... Hahn, B. C. (2007). Variations in K/Th on Mars. Journal of Geophysical Research: Space Physics, 112(3), [E03S06].