Kinetics deuteration in pyrope

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doi: 10.1127/0935-1221/2004/0016-0567
Authors:Blanchard, Marc; Ingrin, Jannick
Author Affiliations:Primary:
Université Paul Sabatier, Laboratoire Mécanismes de Transfert en Géologie, Toulouse, France
Volume Title:European Journal of Mineralogy
Source:European Journal of Mineralogy, 16(4), p.567-576. Publisher: Schweizerbart'sche Verlagsbuchhandlung (Nägele u. Obermiller), Stuttgart, Federal Republic of Germany. ISSN: 0935-1221
Publication Date:2004
Note:In English. 34 refs.; illus., incl. 2 tables
Summary:H-D exchange experiments were performed at 973-1223 K on a Dora Maira pyrope and two from mantle xenoliths. The FTIR spectra of H in the Dora Maira pyrope differs from that for the xenolith samples, with several OH bands between 3600 and 3650 cm-1and between 3510 and 3575 cm-1, respectively. The self-diffusion of D in Dora Maira pyrope is given by D = D0 exp[-140 ± 38 kJ/mol/RT] with log D0 (m2/s) = -5.8 ± 1.9. This activation energy is the same as for diopside and olivine, but the pre-exponential term D0 is one to two orders of magnitude smaller, suggesting that the mechanism of H self-diffusion in the pyrope structure is similar to that for other upper mantle mineral structures. In contrast to the Dora Maira pyrope, for the two pyropes extracted from xenoliths the total concentration of hydrous species is not preserved during H-D exchange: dehydration occurs concurrently with deuteration. The hydrogen exchange in mantle pyropes may be independent of the oxygen fugacity. [R.A.H.]
Sections:Experimental mineralogy
Mineral Groups:Ortho-and ring silicates
Subjects:Activation energy; Crystal chemistry; Dehydration; Deuterium; Diffusion; Experimental studies; FTIR spectra; Garnet group; Hydrogen; Inclusions; Infrared spectra; Ion exchange; Isotopes; Kinetics; Mantle; Mobility; Nesosilicates; Orthosilicates; Pyrope; Silicates; Spectra; Stable isotopes; Temperature; Upper mantle; Water; Xenoliths; Alps; Cottian Alps; Dora Maira Massif; Europe; Italy; Piedmont Alps; Piemonte Italy; Southern Europe; Western Alps; Western Europe; Deuteration
Coordinates:N442000 N451000 E0072500 E0070500
Abstract Numbers:04M/3039
Record ID:2007037361
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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