Preferential low-pH dissolution of pyroxene in plagioclase-pyroxene mixtures: Implications for martian surface materials

Amy C. McAdam, Mikhail Zolotov, Thomas Sharp, Laurie A. Leshin

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Acid weathering of plagioclase-pyroxene mixtures has been investigated with an open system kinetic dissolution model. The modeling reveals that elevated plagioclase/pyroxene ratios observed in some low-albedo martian regions and atmospheric dust could be partially caused by preferential dissolution of pyroxenes at pHs below ∼3-4. Surface materials with smaller grain sizes, affected by lower pH fluids, and/or exposed to longer durations of acid weathering would be enriched in plagioclase. If preferential dissolution is responsible for the observed mineral ratios, the dissolution process likely occurred on a large scale, such as weathering by acid atmospheric precipitates. If dissolution was continuous, modeled timeframes required to produce a high plagioclase/pyroxene ratio are short on geologic timescales; however, it is likely that acid weathering on Mars was episodic, possibly occurring over a longer period of time.

Original languageEnglish (US)
Pages (from-to)90-96
Number of pages7
JournalIcarus
Volume196
Issue number1
DOIs
StatePublished - Jul 1 2008

Keywords

  • Mars
  • Mineralogy
  • surface

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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