Morizet, Y., Paris, M., Di Carlo, I. & Scaillet, B. (2013) Effect of sulphur on the structure of silicate melts under oxidizing conditions. Chem. Geol. 358 131–147.
Added by: Laurent Cournède (2016-03-10 21:23:29)
|Type de référence: Article
Numéro d'identification (ISBN etc.): 0009-2541
Clé BibTeX: Morizet2013
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Mots-clés: angle-spinning nmr, basaltic melts, calcium aluminosilicate glasses, high-resolution si-29, hydrous silicate, mq-mas nmr, non-bridging oxygen, raman-spectroscopy, ray-absorption spectroscopy, Silicate glass speciation, Silicate glass viscosity, solid-state NMR, solid-state NMR, Sulphur dissolution mechanism
Créateurs: Di Carlo, Morizet, Paris, Scaillet
Collection: Chem. Geol.
Consultations : 1/500
Indice de consultation : 3%
Indice de popularité : 0.75%
Inmagmatic systems, sulphur is an important volatile element after C, H and O. Under oxidizing conditions, S dissolves in aluminosilicate melt as sulphate groups (SO42-). The way SO42- groups dissolve in the melt is currently poorly understood. We present experimental results of the effect of SO4 2 -dissolution on the aluminosilicatemelt structure. Glasses of haplogranitic (HPG) and anorthite-diopside eutectic (An-Di) compositions were synthesized at 300 MPa and 1250 degrees C and under oxidizing conditions (.FMQ + 1.7 to+ 3.0). Starting compositionswere equilibrated under fluid-saturated conditions with a mixture of S (0 to 5 wt.\%) and H2O(5 wt.\%). The S andH2O contents of the recovered glasses were determined with EPMA and FTIR, respectively. Solid state NMR was used to investigate the glass structure. Micro-Raman analyses were performed to identify S species present in glass and coexisting fluid phases. The S content determined in glasses changes from 0 to 979 ppm and 0 to 7519 ppm for HPG and An-Di, respectively. S is present in the glasses as Mn+ SO42- groups (Mn+ is possibly Ca2+ in An-Di and Na+ in HPG). 29SiNMR analyses showimportant changes in the An-Di glass structure upon S dissolution. High S content in AnDi glasses induces a strong polymerization of the glasswhichwe explain by the presence of non-bridging oxygen (NBO) promoting the dissolution of S as SO42- groups. On the contrary, the dissolution of S within HPGmelt does not produce visible changes in the silicate melt structure due to the low concentration in NBO in this melt composition. The observed structural changes suggest that An-Di melt physical properties might be affected by S dissolution. S might produce large changes in melt viscosity, but opposite, as compared to H2O for slightly depolymerized aluminosilicate melts. (C) 2013 Elsevier B.V. All rights reserved.
Added by: Laurent Cournède