I-Xe studies of individual Allende chondrules

Nine Allende chondrules and a sample of oxidized Allende matrix material are subjected to iodine-xenon studies, and the model compositions derived are compared with those of the Bjurbole chondrules. Chondrule 6 yields a well-defined isochron, with an apparent age that is later than Bjurbole whole rock. Elemental abundances suggest that all the chondrules except 6 may be pyroxene- or mesostasis-rich. The oxidized matrix sample gives a well defined isochron with an initial I-129/I-127 ratio higher than any plateaus seen in the chondrules, suggesting that the matrix predates the chondrules.