6533b82cfe1ef96bd128ea47
RESEARCH PRODUCT
Determination of U-Pb ages of zircons by direct measurement of the 210Pb/206Pb ratio
I. WendtJ.i. WendtJ.i. WendtD. Tuttassubject
IsotopeGeochemistry and PetrologyAbsolute datingAnalytical chemistryGeologyIsotope dilutionDecay productMass spectrometryGeologyZircondescription
Abstract Precise measurements of the 210Pb/206Pb ratio in zircons permits, for the first time, the determination of complete U-Pb ages by measurement of Pb isotopes only, without determination of the U-Pb ratio by isotope dilution. The 238U daughter isotope 210Pb is generally in radioactive equilibrium with 238U; however, the very short half-life of 210Pb (22.3a) results in extremely low 210Pb/206Pb ratios of ∼ 10−8, especially for Archaean zircons. These ratios have been determined using a Finnigan MAT 262® mass spectrometer equipped with a high abundance sensitivity lens system (RPQ). The accuracy of the 210Pb method has been tested on nine different zircon samples with 207Pb/206Pb ages from 330 to 3365 Ma corresponding to 210Pb/206Pb ratios between 1.31·10−7 and 9.09·10−9. In general, the U-Pb ages calculated using the 210Pb/206Pb ratio are in good agreement with conventional U-Pb age determinations on aliquots of the same sample via isotope dilution.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1993-06-01 | Chemical Geology |