Stability of micas on the surface of Venus

M. Yu Zolotov, B. Fegley, K. Lodders

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Recent thermodynamic modeling shows that some micas might be stable on Venus' surface. However, prior studies considered only pure micas and did not consider mica solid solutions, which are commonly observed on Earth. Here we use chemical equilibrium calculations to evaluate the stability of mica solid solutions on Venus' surface as a function of atmospheric chemistry (H2O and HF abundances, and redox state), and surface elevation. Our prior calculations show that the end-member micas eastonite (KMg2Al3Si2O10(OH)2) and fluorphlogopite (KMg3AlSi3O10F2) are stable on Venus' surface, while the end-member micas phlogopite (KMg3AlSi3O10(OH)2), annite (KFe3AlSi3O10(OH)2), and siderophyllite (KFe2+2Al3Si2O10(OH) 2) are unstable. Based on these results and known petrologic phase relationships, we consider binary solutions of eastonite with either phlogopite or siderophyllite, and fluorphlogopite with phlogopite. We calculate that micas along all three binaries are stable on Venus. Micas containing ∼20 mole% eastonite and ∼80% phlogopite are stable in the lower temperature highlands, and very eastonite-rich micas are stable over Venus' entire surface. Fluorphlogopite-rich micas are also stable over Venus' surface, while fluorphlogopite-poor micas are stable at higher elevations. Iron-poor micas along the eastonite-siderophyllite join, containing > 80 mole% eastonite, are stable in both the highlands and lowlands. Finally, we use the thermodynamic calculations, terrestrial geology, and petrologic phase equilibria to discuss plausible geological settings where micas may be present on Venus. These suggestions are important for the design of geochemical experiments on future lander and automated balloon missions to Venus.

Original languageEnglish (US)
Pages (from-to)245-260
Number of pages16
JournalPlanetary and Space Science
Volume47
Issue number1-2
DOIs
StatePublished - Dec 15 1998
Externally publishedYes

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ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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