PT  - JOURNAL ARTICLE
AU  - Silver, Leon T.
TI  - Uranium-Thorium-Lead Isotope Relations in Lunar Materials
AID  - 10.1126/science.167.3918.468
DP  - 1970 Jan 30
TA  - Science
PG  - 468--471
VI  - 167
IP  - 3918
4099  - http://science.sciencemag.org/content/167/3918/468.short
4100  - http://science.sciencemag.org/content/167/3918/468.full
SO  - Science1970 Jan 30; 167
AB  - The lead isotopic compositions and uranium, thorium, and lead concentrations have been measured on six samples of material from the Sea of Tranquillity. The leads are moderately to very radiogenic; the initial lead concentrations are very low; the uranium and thorium levels are 0.26 to 0.88 and 0.87 to 3.35 parts per million, respectively. The Th/U ratios cluster about a 3.6 value. Apparent ages calculated for four rocks are 4.1 to 4.2 x 109 years. Dust and breccia yield apparent ages of 4.60 to 4.63 x 109 years. The uranium-lead ages are concordant, or nearly so, in all cases. The lunar surface is an ancient region with an extended record of events in the early history of the solar system. discrepancy between the rock ages and dust ages poses a fundamental qusestion about rock genesis on the moon.