U, Th, and Pb concentrations and lead isotopic compositions of Apollo 16 samples are interpreted as follows: (1) an early period of lunar differentiation of either global or regional scale occurred about 4.47 b.y. ago; (2) the Imbrian impact event affected many Apollo 16 samples about 3.99 b.y. ago; (3) some Apollo 16 metaclastic rocks and breccias contain a large amount of KREEP-like material; (4) lead produced in the early history of the moon has been concentrated in lunar highland soils yielding high Pb-207/Pb-206 ratios corresponding to apparent ages of more than 4.8 b.y.; and (5) South Ray Crater soils reflect the approximately 2-b.y.-old event previously proposed for the Apollo 12 and 14 samples.


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    Title :

    U-Th-Pb systematics of some Apollo 16 lunar samples


    Contributors:
    Nunes, P. D. (author) / Tatsumoto, M. (author) / Knight, R. J. (author) / Unruh, D. M. (author) / Doe, B. R. (author)

    Conference:

    Lunar Science Conference ; 1973 ; Houston, TX


    Publication date :

    1973-01-01


    Type of media :

    Miscellaneous


    Type of material :

    No indication


    Language :

    English


    Keywords :


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