Determining major and trace element compositions of exposed melt inclusions in minerals using ToF-SIMS

Melt inclusions (MI), tiny portions of liquid silicate (melt) and gases trapped inside crystals during their growth in magmatic environments, are a valuable geological tool for understanding the evolution of magmas and the source of metals for some ore deposits. Owing to their small size, acquiring the chemical composition of MI is a meticulous process. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a powerful surface analytical technique that provides excellent sensitivity with high mass and spatial resolution. We have begun the study of MI in rocks associated with modern and ancient seafloor hydrothermal systems. The main objective of our experiments is to obtain quantitative data for which we have used as standards quenched glasses with known similar compositions. Specimens were polished and different cleaning conditions (presputtering with either Ar or Cs ions) were examined in order to optimize our results, which were obtained using a Bi cluster ion source. Good quantitative results were obtained for selected major and trace elements (e.g. Mg, Na, K, V, La and Ce).