In magmatic systems, sulphur is an important volatile element after C, H and O. Under oxidising conditions, S dissolves in aluminosilicate melt as sulfates 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 aluminosilicate melt structure. Glasses of haplogranitic (HPG) and anorthite-diopside eutectic (An-Di) compositions were synthesised at 300 MPa and 1250°C and under oxidising conditions (FMQ+1.7 to +3.0). Starting compositions were equilibrated under fluid-saturated conditions with a mixture of S (0 to 5 wt.%) and H2O (5 wt.%). The S and H2O 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.
