ArticlesAge Measurements

Age Determinations and Isotopic Abundance Measurements on Lunar Samples

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Science  30 Jan 1970:
Vol. 167, Issue 3918, pp. 479-480
DOI: 10.1126/science.167.3918.479

Abstract

A K-Ar age of 2300 x 106 years has been determined for a sample of type A crystalline rock (57,34). The presence of an anomalously large quantity of 4°Ar, in a sample of type C breccia (65,35) precluded the calculation of its K-Ar age. Both of the rock types are characterized by low Rb/Sr ratios and consequently low 87Sr/86Sr values. The U-Th-Pb results for a sample of type D fines (84,33) yield a 207Pb/206Pb age of 4760 x 106 years, but ages based on U-Pb and Th-Pb ratios are anomalously high. Isotopic compositions of Li, K, Rb, Sr, U, and Th are very close to the accepted values for terrestrial materials.