title: Lead isotopic ages of chondrules and calcium-aluminum-rich inclusions.
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 initial 26Al/27Al ratios and supports the chronological significance of the 26Al-26Mg systematics.
authors.affiliation: Department of Earth Sciences, Royal Ontario Museum, Toronto, ON M5S 2C6, Canada. yamelin@NRCan.gc.ca
authors.forename: Yuri
authors.initials: Y
authors.lastname: Amelin
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Krot
authors.forename: Ian D
authors.initials: ID
authors.lastname: Hutcheon
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Ulyanov