Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 17 May 1991:
Vol. 252. no. 5008, pp. 946 - 949
DOI: 10.1126/science.252.5008.946
Prev | Table of Contents | Next

Articles

Calcic Micas in the Allende Meteorite: Evidence for Hydration Reactions in the Early Solar Nebula

LINDSAY P. KELLER 1 and PETER R. BUSECK 1

1 Departments of Geology and Chemistry, Arizona State University, Tempe, AZ 85287

Two calcic micas, clintonite and margarite, have been identified in alteration products in a calcium- and aluminum-rich inclusion (CAI) in the Allende meteorite. Clintonite replaces grossular in alteration veins, and margarite occurs as lamellae in anorthite. Their occurrence suggests that, in addition to undergoing high-temperature alteration by a volatile and iron-rich vapor that produced the grossular and anorthite, some CAIs underwent alteration at moderate temperatures (le400 kelvin). Petrographic evidence suggests that the calcic micas formed before accretion but after the formation of the layered rim sequences that surround the CAL. These calcic micas provide strong evidence that, contrary to theoretical calculations, some hydration reactions occurred in the early solar nebula.

Submitted on November 20, 1990
Accepted on February 25, 1991


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
53Mn-53Cr Dating of Fayalite Formation in the CV3 Chondrite Mokoia: Evidence for Asteroidal Alteration.
I. D. Hutcheon, A. N. Krot, K. Keil, D. L. Phinney, and E. R. Scott (1998)
Science 282, 1865-1867
   Abstract »    Full Text »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)