New Olivine Reference Materials for Secondary Ion Mass Spectrometry Oxygen Isotope Measurements

Abstract

To accurately analyze the oxygen isotope of olivine using secondary ion mass spectrometry (SIMS), appropriate standard materials are required to calibrate for matrix effects caused by chemical composition differences between the samples and the standard materials. In this study, we investigated the homogeneity of oxygen isotopes in two natural olivine minerals using a secondary ion mass spectrometer to evaluate their potential as standard materials. The two minerals, JAY03-3 and JAY02-4, with forsterite contents of 99.3% and 99.6%, respectively, were evaluated for homogeneity in oxygen isotope composition. The recommended oxygen isotope values were characterized using CO2 laser fluorination, and the homogeneity was tested with in situ SIMS oxygen isotope measurements. Our results show that the δ18O value determined via CO2 laser fluorination for JAY03-3 is 16.37 ± 0.22‰ (2 s) and for JAY02-4 is 18.29 ± 0.28‰ (2 s). The precision of SIMS oxygen isotope measurements is 0.57‰ (2 s) for JAY03-3 and 0.70‰ (2 s) for JAY02-4. These two minerals have the potential to be used as standard materials for calibrating the oxygen isotope value of end-member forsterite during in situ analysis of SIMS oxygen isotope.