The partial molar volume of CO2 (VCO2) in silicate melt was determined for a komatiite composition using high pressure sink/float experiments in a multi-anvil press. The density of the experimental melt at pressure was determined by observing sinking and floating of pure forsterite (Fo100) and 90% forsterite (Fo90) buoyancy markers. Values for VCO2 were bracketed at 4.3 GPa (23.71 cm3/mol) and at 5.5 GPa (22.06 cm3/mol), normalized to 1850°C. Combining the current data with previous work we now more accurately constrain the compression curve of VCO2 over the pressure range of 1 bar to 20 GPa. These data allow the calculation of density at pressure of carbonated silicate melts, such as kimberlite and silica undersaturated alkali basalts, and the determination of their buoyancy and eruptibility
