A Nebular Origin for Chondritic Fine-Grained Phyllosilicates
Fred J. Ciesla,1*
Dante S. Lauretta,1
Barbara A. Cohen,2
Lon L. Hood1
Hydrated minerals occur in accretionary rims around
chondrules in CM chondrites. Previous models suggested that these
phyllosilicates did not form by gas-solid reactions in the canonical
solar nebula. We propose that chondrule-forming shock waves in
icy regions of the nebula produced conditions that allowed rapid
mineral hydration. The time scales for phyllosilicate formation are
similar to the time it takes for a shocked system to cool from the
temperature of phyllosilicate stability to that of water ice
condensation. This scenario allows for simultaneous formation of
chondrules and their fine-grained accretionary rims.
1 Department of Planetary Sciences, Lunar and
Planetary Laboratory, University of Arizona, 1629 East University
Boulevard, Tucson, AZ 85721, USA.
2 Hawaii Institute
of Geophysics and Planetology, University of Hawaii, Honolulu, HI
96822, USA.
*
To whom correspondence should be addressed. E-mail:
fciesla{at}lpl.arizona.edu
