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Melting kinetics of granitic powder aggregates at 1175 degrees C, 1 atm

Karine Devineau, Michel Pichavant and Frederic Villieras
Melting kinetics of granitic powder aggregates at 1175 degrees C, 1 atm
European Journal of Mineralogy (June 2005) 17 (3): 387-398


Melting experiments of pressed granitic powders (10% < 3.23 mu m, 50% < 31.63 mu m, 90% < 169.85 mu m) have been performed at 1175 degrees C, 1 atm for different run durations (5, 10, 40 mn and 3, 24, 68 h). During partial melting, quartz and feldspars progressively decrease in abundance, the amount of melt produced increases sharply after 40 mn and leads to a strong decrease of the porosity of the powder (from 42% before heat-treatment to 10% after 68 h). In the 5 mn charge, thin glass films (1-2 mu m) appear cementing small particles grains and narrow glass channels are formed and trapped within both albite and K-feldspar. Newly-formed K-feldspars appear in the 10 and 40 mn charges. They are both texturally and compositionally distinctive from the original feldspars. All feldspars have totally disappeared after 3 h and quartz (up to 330 mu m) persists in the longest experiment (68 h). For durations longer than 40 mn, glass compositions are chemically zoned. They vary mainly between two end-members, one rich in normative feldspar components and poor in normative quartz and the other rich in normative quartz corresponding to areas close to the quartz interface. The melting reaction is governed by disequilibrium melting. Two melting regimes were identified: (1) a low melt fraction regime corresponding to heterogeneous nucleation of melt at the surface and within interiors of both albite and K-feldspar and (2) a high melt fraction regime kinetically controlled by diffusive mass transport within the melt layer. The lack of leucite implies that the melting relations of K-feldspar observed in this study are congruent. About 50 days are needed for the melting reaction to approach chemical equilibrium at 1175 degrees C.

ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 17
Serial Issue: 3
Title: Melting kinetics of granitic powder aggregates at 1175 degrees C, 1 atm
Affiliation: Laboratoire Environnement et Mineralurgie, Vandoeuvre les Nancy, France
Pages: 387-398
Published: 200506
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 28
Accession Number: 2005-044754
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
Secondary Affiliation: ISTO, FRA, France
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200526
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