Geophysical and geochemical evolution of the lunar magma oceanThere is increasing evidence that at least the outer few hundred kilometers of the moon were melted immediately following accretion. This paper studies the evolution of this lunar magma ocean. The long time scale for solidification leads to the inference that the plagioclase-rich (ANT) lunar crust began forming, perhaps preceded by local accumulations termed 'rockbergs', at the very beginning of the magma ocean epoch. In this view the cooling and solidification of the magma ocean was primarily controlled by the rate at which heat could be conducted across the floating ANT crust. Thus the thickness of the crust was the factor controlling the lunar solidification time. Heat arising from enthalpy of crystallization was transported in the magma by convection. Mixing length theory is used to deduce the principal flow velocity (typically several cm/s) during convection. The magma ocean is deduced to have been turbulent down to a characteristic length scale of the order of 100 m, and to have overturned on a time scale of the order of 1 yr for most of the magma ocean epoch.
Document ID
19790055105
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Herbert, F. (Arizona Univ. Tucson, AZ, United States)
Drake, M. J. (Arizona Univ. Tucson, AZ, United States)
Sonett, C. P. (Arizona, University Tucson, Ariz., United States)