Disequilibrium partitioning of oxygen isotopes associated with sector zoning in quartz

Détails

ID Serval
serval:BIB_371D219177D7
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Disequilibrium partitioning of oxygen isotopes associated with sector zoning in quartz
Périodique
Geology
Auteur(s)
Onasch C.M., Vennemann T.W.
ISSN-L
0091-7613
Statut éditorial
Publié
Date de publication
1995
Peer-reviewed
Oui
Volume
23
Pages
1103-1106
Langue
anglais
Résumé
Fractionation of oxygen isotopes during crystal growth is commonly
assumed to be an equilibrium process. We present evidence here that
large variations in delta(18)O values in a zoned vein quartz crystal are
the result of disequilibrium partitioning between fluid and crystal.
Within a single crystal,vith well-developed concentric and sector
zoning, delta(18)O values determined with laser extraction techniques on
milligram- to submilligram-sized samples range from 4.7 parts per
thousand to 7.3 parts per thousand. Core to rim variations within single
growth sectors fluctuate by 2.6 parts per thousand, whereas differences
between adjacent sectors along the same growth zone can exceed 2.0 parts
per thousand. In contrast, fluid-inclusion homogenization temperatures
and salinities are relatively constant and show no effect of grow th or
sector zoning. Differences in delta(18)O values between sectors along
the same growth zone cannot result from variations in the oxygen isotope
composition of the fluid and strongly suggest disequilibrium
partitioning of oxygen isotopes between fluid and the growing crystal.
The cause of this disequilibrium is believed to be due to differences in
surface structure and/or growth mechanisms between nonequivalent faces.
Création de la notice
29/09/2012 17:23
Dernière modification de la notice
03/03/2018 16:03
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