Determination of trace-element partitioning between fluid and melt using LA-ICP-MS analysis of synthetic fluid inclusions in glass

The partitioning of trace elements between an aqueous chloride fluid phase and a granitic melt was investigated using LA-ICP-MS analysis of synthetic fluid inclusions in glass. In these experiments, a granitic melt was equilibrated with included vesicles containing the chloride solution at 850°C and 2 kbar. Rapid isobaric quenching of the system preserves the host phase as an unfractured granitic glass which contains typically more than a hundred individual two-phase fluid inclusions. Glass matrix and fluid inclusions were analysed by LA-ICP-MS for Na, K, Al, Cl, Nb, Cs, Mo, and W. For quantification the integrated fluid inclusion intensities were corrected for the contribution of the doped host glass to the inclusion signal using integrated intensities for the highly compatible elements Si and Al. Quantitative data for the fluid inclusions were calculated using Cl as internal standard element. The reproducibility of inclusion analyses for Na, K, Cs, Mo, and W ranges between 3 and 25% relative. Analyses of fluid inclusions and the host glass permit the calculation of partition coefficents for Na, K, Cs, Mo, and W. The resultant partition coefficient data were compared with the results of partitioning experiments using classical bulk analytical techniques.