The Formation of Chondrules at High Gas Pressures in the Solar Nebula
Albert Galy,*
Edward D. Young,
Richard D. Ash,
R. Keith O'Nions
High-precision magnesium isotope measurements of whole chondrules
from the Allende carbonaceous chondrite meteorite show that some
aluminum-rich Allende chondrules formed at or near the time of
formation of calcium-aluminum-rich inclusions and that some others
formed later and incorporated precursors previously enriched in
magnesium-26. Chondrule magnesium-25/magnesium-24 correlates with
[magnesium]/[aluminum] and size, the aluminum-rich, smaller chondrules being the most enriched in the heavy isotopes of magnesium. These relations imply that high gas pressures prevailed during chondrule formation in the solar nebula.
Department of Earth Sciences, University of Oxford, Parks Road,
Oxford, OX1 3PR, UK.
*
To whom correspondence should be addressed. E-mail:
albert00{at}esc.cam.ac.uk
Present address: Department of Earth Sciences,
University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK.
