A Low Viscosity Lunar Magma Ocean Forms a Stratified Anorthitic Flotation Crust With Mafic Poor and Rich Units
Abstract
Much of the lunar crust is monomineralic, comprising >98% plagioclase. The prevailing model argues the crust accumulated as plagioclase floated to the surface of a solidifying lunar magma ocean (LMO). Whether >98% pure anorthosites can form in a flotation scenario is debated. An important determinant of the efficiency of plagioclase fractionation is the viscosity of the LMO liquid, which was unconstrained. Here we present results from new experiments conducted on a late LMO‐relevant ferrobasaltic melt. The liquid has an exceptionally low viscosity of to Pa s at experimental conditions (1,300–1,600°C; 0.1–4.4 GPa) and can be modeled by an Arrhenius relation. Extrapolating to LMO‐relevant temperatures, our analysis suggests a low viscosity LMO would form a stratified flotation crust, with the oldest units containing a mafic component and with very pure younger units. Old, impure crust may have been buried by lower crustal diapirs of pure anorthosite in a serial magmatism scenario.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 21, 2017
- Source ID
- 10.1002/2017gl075703
Entities
People
- Edward W. Marshall
- James E Gardner
- Jung-Fu Lin
- Nick Dygert
- Yoshio Kono
Organizations
- Carnegie Institution for Science
- Intelligence Community Postdoctoral Research Fellowship Program
- National Science Foundation
- University of Tennessee
- University of Texas at Austin