Effect of sulphur on the structure of silicate melts under oxidizing conditions

Research areas:

• Intérieurs planétaires (2011 - 2016)

Year:

2013

Authors:

• Yann Morizet
• Michael Paris
• Ida Di Carlo
• Bruno Scaillet

Journal:

CHEMICAL GEOLOGY

Volume:

358

Pages:

131-147

Month:

NOV 4

ISSN:

0009-2541

BibTex:

@article{WOS:000326573500012, author = "Yann Morizet and Michael Paris and Ida Di Carlo and Bruno Scaillet", abstract = "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.", doi = "10.1016/j.chemgeo.2013.09.004", extra = "PICL", issn = "0009-2541", journal = "CHEMICAL GEOLOGY", month = "NOV 4", pages = "131-147", title = "{E}ffect of sulphur on the structure of silicate melts under oxidizing conditions", volume = "358", year = "2013", }

Abstract:

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.