Effect of initial radioactive-daughter disequilibrium on U-Pb isotope apparent ages of young minerals
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Abstract
Most calculations of U-Pb isotope apparent ages are made by use of equations that assume initial secular equilibrium of the uranium decay-chains. The possible error in calculated Pb/U isotope ratios arising from this assumption (especially for ores of sandstone uranium deposits) can be over 10 percent at 1 million years and exceed analytical error even at a 30 m.y. apparent age. Use of the more general equations (adapted from the Bateman equations) is desirable for calculation and interpretation of U-Pb isotope apparent ages of both open and closed systems in the range of 2 to 20 m.y. and is essential for apparent ages less than about 2 m^y. For very young sandstone uranium deposits, a significant uncertainty in the 208Pb/238U systematics may still persist owing to the uncertainty in the initial value of 234U/238U.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Effect of initial radioactive-daughter disequilibrium on U-Pb isotope apparent ages of young minerals |
| Series title | Journal of Research of the U.S. Geological Survey |
| Volume | 5 |
| Issue | 6 |
| Year Published | 1977 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Description | 5 p. |
| First page | 663 |
| Last page | 667 |
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