Juske:

Yes and no.  As I stated, the dissolution of carbonate will likely cause
a modification of the stable isotope ratios if for instance there are
admixtures of different minerals and one is preferentially dissolved.
Molluscs are a good example of calcite and argonite.

The Geology paper on "coral roasting" deals with stable isotope ratios.
I think this was written by a fellow from LSU and the discussion by
Peter Swart...I could be wrong.

One could also conduct the experiment on their own with similar reagents
and techniques.

It is interesting to note that we have been conducting isotope analyses
of organic matter in things like calcareous algae and have found that
chlorox treatments only get the surface coating of organic matter...We
have pre-treated with dilute chlorox and not and measured the d13C
values of the organic matter with no observable difference in either the
carbonate or organic matter. We roast aragonite samples in vacuo at 200
degrees C prior to analysis.

When we did this discussion a year ago - nobody said anything about the
interaction of the water and CO2 inclusions with organic matter during
roasting.  Perhaps this is a good experiment for someone.

I hope this has helped in some way,

Scott


Juske Horita wrote:

> Dear Scott and others:
>         References Scott mentioned are about the effect of
> pretreatment on
> mineralogy and trace elements, not on stable isotopes; am I right?.
> I'm,
> like Reed, very interested in how to pretreat organic-rich carbonate
> samples
> for isotope analysis; vacuum roast vs. bleaching vs. plasma ashing or
> some
> other methods? What happen, if no treatment?
> Any comments are appreciated.
> *****************************************
> Juske Horita
> Chemical and Analytical Sciences Division
> Oak Ridge National Laboratory
> P.O.Box 2008, MS6110
> Oak Ridge, TN 37831-6110
> (423) 576-2750
> Fax: (423) 574-4961
> e-mail: [log in to unmask]
> *****************************************



--
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Scott J. Carpenter
Assistant Professor

Phone:        (972) 883-2481
FAX:          (972) 883-2537
Laboratory:   (972) 883-2632

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Department of Geosciences             Department of Geosciences
The University of Texas at Dallas     The University of Texas at Dallas
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