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Lead Isotopic Ages of Chondrules and Calcium-Aluminum-Rich Inclusions

Science  06 Sep 2002:
Vol. 297, Issue 5587, pp. 1678-1683
DOI: 10.1126/science.1073950

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Abstract

The lead-lead isochron age of chondrules in the CR chondrite Acfer 059 is 4564.7 ± 0.6 million years ago (Ma), whereas the lead isotopic age of calcium-aluminum–rich inclusions (CAIs) in the CV chondrite Efremovka is 4567.2 ± 0.6 Ma. This gives an interval of 2.5 ± 1.2 million years (My) between formation of the CV CAIs and the CR chondrules and indicates that CAI- and chondrule-forming events lasted for at least 1.3 My. This time interval is consistent with a 2- to 3-My age difference between CR CAIs and chondrules inferred from the differences in their initial26Al/27Al ratios and supports the chronological significance of the 26Al-26Mg systematics.

  • * Present address: Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada.

  • To whom correspondence should be addressed. E-mail: yamelin{at}NRCan.gc.ca

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