Crystals stirred up

2. Numerical insights into the formation of the earliest crust on the Moon

Jenny Suckale, Linda Elkins-Tanton, James A. Sethian

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

This is the second paper in a two-part series examining the fluid dynamics of crystal settling and flotation in the lunar magma ocean. In the first paper, we develop a direct numerical method for resolving the hydrodynamic interactions between crystals and their feedback on the flow field in magmatic liquid. In this paper, we use this computational technique to test the leading model for the formation of the earliest crust on the Moon. The anorthositic lithology of the lunar crust is thought to have been formed by the flotation of buoyant plagioclase crystals at a time when the lunar mantle was still wholly or largely molten. This model is appealing from an observational point of view, but its fluid dynamical validity is not obvious, because (1) plagioclase probably started crystallizing very late (i.e., when the magma ocean was already 80% solidified) and (2) a significant portion of the shallow lunar crust consists of almost pure plagioclase (>90 vol. %), requiring very efficient plagioclase segregation. The goal of this study is to better understand the fluid dynamical conditions that hinder or facilitate crystal settling or flotation. Our approach complements earlier studies by explicitly linking the petrological and fluid dynamical evolution and by focusing on the effect of increasing crystal fraction. We find that crystal settling was probably possible throughout the entire solidification history of the lunar magma ocean as long as crystal sizes were sufficiently large (r>1 mm) and crystal fraction sufficiently low (<13%).

Original languageEnglish (US)
Article numberE08005
JournalJournal of Geophysical Research E: Planets
Volume117
Issue number8
DOIs
StatePublished - 2012
Externally publishedYes

Fingerprint

Moon
moon
crusts
crystal
crust
Crystals
plagioclase
flotation
crystals
settling
lunar crust
Flotation
magma
oceans
Fluids
fluid
fluids
lunar mantle
ocean
Lithology

ASJC Scopus subject areas

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

Cite this

Crystals stirred up : 2. Numerical insights into the formation of the earliest crust on the Moon. / Suckale, Jenny; Elkins-Tanton, Linda; Sethian, James A.

In: Journal of Geophysical Research E: Planets, Vol. 117, No. 8, E08005, 2012.

Research output: Contribution to journalArticle

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