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Lunar evolution - The first 600 million yearsFrom a stepwise-heating experiment on neutron-irradiated samples of whole rock and a plagioclase separate, an Ar-40/Ar-39 age of 4.26 plus or minus 0.02 G.y. was determined for the Apollo 17 troctolite 76535. This rock is believed to have formed as a result of very slow cooling at a depth of 10 to 40 km, and hence furnishes direct evidence that the moon was chemically zoned before 4.26 G.y. The age of the rock is associated with the Serenitatis Basin forming event. The formation of the Serenitatis Basin is then deduced to have occurred 4.26 plus or minus 0.02 G.y. ago, about 300 m.y. before the Imbrium event. It appears that the major basin forming era on the near side of the moon lasted longer than 300 m.y. The grouping of many lunar rock ages at 3.9 to 4.0 G.y. is most likely due to the fact that the Imbrium ejecta predominates all highland landing sites.
Document ID
19750036023
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Husain, L.
Schaeffer, O. A.
(New York, State University Stony Brook, N.Y., United States)
Date Acquired
August 8, 2013
Publication Date
January 1, 1975
Publication Information
Publication: Geophysical Research Letters
Volume: 2
Subject Category
Lunar And Planetary Exploration
Accession Number
75A20095
Funding Number(s)
CONTRACT_GRANT: NGL-33-015-130
Distribution Limits
Public
Copyright
Other

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