>Any time you see solution and reprecipitation, there is a real chance of a
>shift of O or C isotope ratio. For oxygen, we have documented shifts of up
>to 10%o over 200 microns in calcite, 14%o over 400 microns along cracks in
>quartz, 25%o across a few microns in quartz overgrowths, and 10%o over a
>few 100 microns in magnetite. I can send reprints.

John Valley


        Dear Isogeochemists,
>
>        Can anybody tell if pressure-solution along cleavage in a limestone
>or a marble may shift the carbonate C- and O-isotope compositions, not only
>because of the infiltration of an exotic fluid, but especially because of a
>dissolution mechanism similar to decarbonatation reactions (those often
>modelled by a Rayleigh fractionation model) ?
>        Any personal statement or bibliographic reference is welcome.
>Cheers,
>Eric
>
>---------------------------------------------------------------------------
> Eric Pili
> Center for Isotope Geochemistry
> University of California - Berkeley
> Lawrence Berkeley National Laboratory - Earth Sciences Division
> MS: 70A-3363 - 1 Cyclotron road , Berkeley, CA 94720, USA
> Phone: 510-495-2443 (office) or 510-486-4975 (lab) - Fax: 510-486-5496
>
>email : [log in to unmask]
>web pages :   http://www.ens-lyon.fr/~pili
>
>Formerly and occasionally at :
> Laboratoire de Sciences de la Terre - Ecole Normale Superieure de Lyon
> 46, Allee d'Italie - F 69364 Lyon Cedex 07 - France


John W. Valley,
    Professor and Chairman             phone: 608-263-5659
Dept. of Geology and Geophysics        fax:   608-262-0693
University of Wisconsin
1215 W. Dayton St.
Madison, WI 53706, USA
            http://www.geology.wisc.edu/people/valley.html