238U/235U variations in meteorites

Extant 247Cm and implications for Pb-Pb dating

G. A. Brennecka, S. Weyer, Meenakshi Wadhwa, P. E. Janney, J. Zipfel, Ariel Anbar

Research output: Contribution to journalArticle

111 Citations (Scopus)

Abstract

The 238U/235U isotope ratio has long been considered invariant in meteoritic materials (equal to 137.88). This assumption is a cornerstone of the high-precision lead-lead dates that define the absolute age of the solar system. Calcium-aluminum-rich inclusions (CAls) of the Allende meteorite display variable 238U/235U ratios, ranging between 137.409 ± 0.039 and 137.885 ± 0.009. This range implies substantial uncertainties in the ages that were previously determined by lead-lead dating of CAls, which may be overestimated by several million years. The correlation of uranium isotope ratios with proxies for curium/uranium (that is, thorium/uranium and neodymium/uranium) provides strong evidence that the observed variations of 238U/235U in CAls were produced by the decay of extant curium-247 to uranium-235 in the early solar system, with an initial 247Cm/235U ratio of approximately 1.1 × 10-4 to 2.4 × 10-4.

Original languageEnglish (US)
Pages (from-to)449-451
Number of pages3
JournalScience
Volume327
Issue number5964
DOIs
StatePublished - Jan 22 2010

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Meteoroids
Uranium
Curium
Aluminum
Solar System
Calcium
Isotopes
Thorium
Neodymium
Proxy
Uncertainty
Lead

ASJC Scopus subject areas

  • General

Cite this

238U/235U variations in meteorites : Extant 247Cm and implications for Pb-Pb dating. / Brennecka, G. A.; Weyer, S.; Wadhwa, Meenakshi; Janney, P. E.; Zipfel, J.; Anbar, Ariel.

In: Science, Vol. 327, No. 5964, 22.01.2010, p. 449-451.

Research output: Contribution to journalArticle

Brennecka, G. A. ; Weyer, S. ; Wadhwa, Meenakshi ; Janney, P. E. ; Zipfel, J. ; Anbar, Ariel. / 238U/235U variations in meteorites : Extant 247Cm and implications for Pb-Pb dating. In: Science. 2010 ; Vol. 327, No. 5964. pp. 449-451.
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