ArticlesAge Measurements

Rubidium-Strontium Age and Elemental and Isotopic Abundances of Some Trace Elements in Lunar Samples

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Science  30 Jan 1970:
Vol. 167, Issue 3918, pp. 476-479
DOI: 10.1126/science.167.3918.476


Data on six lunar crystalline rocks give an apparent Rb-Sr isochron age of 4.42 ± 0.24 x 109 years (95 percent confidence limits) and initial 87Sr/86Sr ratio similar to that in a basaltic achondrite. Relationships between K, Rb, Sr, and Ba and depletion of Eu in these samples point to plagioclase separation from the melts that produced these rocks. The abundance of 157Gd in the three lunar samples is similar to terrestrial abundance within < 0.2 percent, thus setting a limit of < 6 x 1015 neutrons per square centimeter for the integrated thermal neutron flux difference between lunar and terrestrial materials.

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