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The estimation of NaSi-CaAl interdiffusion rates in peristerite by homogenization experiments

Gabriele Baschek and Wilhelm Johannes
The estimation of NaSi-CaAl interdiffusion rates in peristerite by homogenization experiments
European Journal of Mineralogy (April 1995) 7 (2): 295-307

Abstract

Average NaSi-CaAl interdiffusion coefficients (<$E D tilde>) were determined for two peristerites from Steirmark, Austria, and from Burma [Myanmar], at 1 GPa, 800 and 900 degrees C, using an additional N (sub 2) -H (sub 2) O fluid phase with XH (sub 2) O 0.5, 0.3, 0.1 and 0.0, by means of the homogenization method. The results at 900 degrees C show that the <$E D tilde> values of both peristerites are a function of the N (sub 2) -H (sub 2) O fluid composition; an increase in XH (sub 2) O of 0.1 leads to an increase in the diffusion coefficients by a factor of 2.2. The estimated <$E D tilde> values of the two different peristerites using the homogenization method differ by more than one order of magnitude from each other at the same experimental conditions. These results are explained as due to the weakness of the homogenization method for the estimation of diffusion data for plagioclases with respect to the determination of the homogenization time (t (sub h) ). This time is usually measured by the change in lamellar microstructure of the experimental products as seen by TEM. Corrections for the determination of t (sub h) are proposed on the basis of calculated concentration curves for the peristerites as a function of diffusion time; with these corrections, nearly identical <$E D tilde> values are obtained for both peristerites.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 7
Serial Issue: 2
Title: The estimation of NaSi-CaAl interdiffusion rates in peristerite by homogenization experiments
Affiliation: Universitaet Hannover, Institut fuer Mineralogie, Hanover, Federal Republic of Germany
Pages: 295-307
Published: 199504
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 24
Accession Number: 1995-027332
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, 2 plates
N09°00'00" - N28°45'00", E92°00'00" - E101°45'00"
N46°34'60" - N47°45'00", E13°30'00" - E16°15'00"
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199510
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