Distribution and variation of plagioclase compositions on Mars

Keith A. Milam, Harry Y. McSween, Jeffrey Moersch, Philip Christensen

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


This study presents the first global compositional maps of plagioclase, the most abundant mineral in the Martian crust. Linear deconvolutions of spectra from the Thermal Emission Spectrometer (TES) allowed calculation of average plagioclase compositions for dust-free areas on Mars 60 of the equator (approximately 40% of the surface for this range of latitudes). As a whole, surface type 1 and 2 terrains are virtually identical with respect to their average plagioclase compositions, ∼An60. The majority of TES observations were modeled as labradorite and bytownite (between An50 and An90), while fewer observations were modeled with other plagioclase compositions that did not correlate with specific geologic terrains. The lack of diversity in average plagioclase compositions across multiple geologic units may represent an upper Martian crust with minimal variation in plagioclase compositions. Alternatively, aeolian, fluvial, and/or impact activity may have redistributed heterogeneous crustal material forming a relatively homogeneous, global surface layer.

Original languageEnglish (US)
Article numberE09004
JournalJournal of Geophysical Research: Planets
Issue number9
StatePublished - 2010

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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