247Cm in D'Orbigny meteorite.

JAGOUTZ EMIL,; KUBNY A,; ZARTMAN R,; MARIA EUGENIA VARELA

Houston- Texas

Congreso; XXXVIII Lunar and Planetary Science Conference. .; 2007

In this study we report238U /235U ratios measured on minerals concentrates from D`Orbigy meteorite. While the major parts of the minerals from D`Orbigny meteorite are concordant in the U-Pb ages as well as the Pb-Pb ages (4563 Ma) [1], we found a varia-tion of the Pb age in some mineral-fractions. This variation in the 207Pb/206Pb age is close to the Pb isotopic fractionation of an ion-counting system. However, we verified this abnormal excess in 207Pb using the Faraday cup. The fractionation in the Faraday cup is smaller and better reproducible than using the ion-counting system. It would be the best to use a Pb double spike to fully solve this prob-lem.