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Timing of Crystallisation of the Lunar Magma Ocean Constrained by the Oldest ZirconThe presently favoured concept for the early evolution of the Moon involves consolidation of debris from a giant impact of a Mars sized body with Earth forming a primitive Moon with a thick global layer of melt referred to as the Lunar Magma Ocean1 . It is widely accepted that many significant features observed on the Moon today are the result of crystallisation of this magma ocean. However, controversy exists over the precise timing and duration of the crystallisation process. Resolution of this problem depends on the establishment of precise and robust key crystallisation time points. We report a 4417 6 Myr old zircon in lunar breccia sample 72215,195, which provides a precisely determined younger limit for the solidification of the Lunar Magma Ocean. A model based on these data, together with the age of the Moon forming giant impact, defines an exponential time frame for crystallisation and suggests formation of anorthositic crust after about 80-85% of the magma ocean was solidified. In combination with other zircon ages the 4417 +/- 6 Myr age also suggests that the very small (less than a few per cent) residual portion of the magma ocean continued to solidify during the following 300-500 m.y.
Document ID
20090010193
Document Type
Preprint (Draft being sent to journal)
External Source(s)
Authors
Nemchin, A.
(Western Australian School of Mines Kalgoorlie, Australia)
Timms, N.
(Western Australian School of Mines Kalgoorlie, Australia)
Pidgeon, R.
(Western Australian School of Mines Kalgoorlie, Australia)
Geisler, T.
(University of Munster Munster, Germany)
Reddy, S.
(Western Australian School of Mines Kalgoorlie, Australia)
Meyer, C.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2009
Publication Information
Publication: Nature Geoscience
Volume: 2
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
JSC-17744
Distribution Limits
Public
Copyright
Public Use Permitted.
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