| Summary: | The primary mineral assemblages and initial ^(26)Al/^(27)Al ratios of rare calcium-aluminum–rich inclusions (CAIs) from enstatite (E) chondrites are similar to those of CAIs from other chondrite classes. CAIs from all chondrite classes formed under oxidizing conditions that are much different from the reducing conditions under which the E chondrites formed. Either CAIs formed at an earlier, more oxidizing epoch in the region where E chondrites ultimately formed, or they formed at a different place in the solar nebula and were transported into the E chondrite formation region. © 2000 American Association for the Advancement of Science. 19 April 2000; accepted 15 June 2000. Supported by NASA grants NAG5-7396 (G.J.M.), NAG5-4083 (G.J.W.), and NAG5-8158 (G.R.H.). We thank the Antarctic Meteorite Working Group and NASA Johnson Space Center for providing the Antarctic meteorite thin sections. Caltech Division Contribution 8652 (1044).
|
|---|