Compositional heterogeneity of the ancient Martian crust

Analysis of Ares Vallis bedrock with THEMIS and TES data

A. Deanne Rogers, Philip Christensen, Joshua L. Bandfield

Research output: Contribution to journalArticle

65 Citations (Scopus)

Abstract

THEMIS multispectral and thermophysical information combined with TES hyperspectral and albedo data is used as a powerful high spectral/spatial resolution tool to investigate the mineralogic heterogeneity of ancient Martian crust exposed in Ares Vallis bedrock. Three major spectral units are present in the upper Ares Vallis region: (1) a regional unit that is composed primarily of a high-silica (Si/O > ∼0.35) component, with lesser amounts of plagioclase and pyroxene, and is associated with channel wall rock and surrounding plains; (2) a pyroxene- and olivine-rich rock unit exposed as a ∼250 m thick contiguous layer in the wall rock of Ares Vallis, as well as in isolated exposures in the plains outside of the channel; and (3) a unit composed of plagioclase, pyroxene, and lesser high-silica component(s) (Si/O > ∼0.35) that primarily occurs as low-albedo sand. The spatial and stratigraphic distribution of these units suggests that the pyroxene- and olivine-enriched unit may be extrusive and/or intrusive in origin, indicating that this region experienced either a single stage or repeated episodes of olivine-enriched magmatism during the first 1.5 Gyr of crust formation. This olivine enrichment may have been caused by a larger degree of mantle partial melting, facilitated by higher mantle temperature, melting from a more depleted mantle source, and/or less olivine fractionation relative to regional rock parent magmas. The olivine-rich unit is similar in thermophysical character to previously published olivine-bearing terrains on Mars, but the derived modal mineralogy consists of >∼20% more pyroxene and less plagioclase than those terrains.

Original languageEnglish (US)
Pages (from-to)1-26
Number of pages26
JournalJournal of Geophysical Research E: Planets
Volume110
Issue number5
DOIs
StatePublished - May 20 2005

Fingerprint

bedrock
olivine
crusts
crust
pyroxene
plagioclase
Wall rock
rocks
Earth mantle
wall rock
albedo
plains
Silicon Dioxide
Bearings (structural)
silica
Rocks
melting
silicon dioxide
mantle
Mineralogy

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

Compositional heterogeneity of the ancient Martian crust : Analysis of Ares Vallis bedrock with THEMIS and TES data. / Rogers, A. Deanne; Christensen, Philip; Bandfield, Joshua L.

In: Journal of Geophysical Research E: Planets, Vol. 110, No. 5, 20.05.2005, p. 1-26.

Research output: Contribution to journalArticle

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