Europium isotope fractionation in highly fractionated igneous rocks with large Eu negative anomaly

One of peculiar geochemical characteristics in the chondrite-normalized REE patterns from highly fractionated granites and high silica rhyolite is extremely large negative Eu anomaly (Eu/Eu* < 0.10) due to very low concentration of Eu. Particularly, Eu provides a valuable information for evolution processes of the earth and planetary materials. Eu has only two isotopes, 151Eu and 153Eu. In this study, Eu isotope ratios from highly fractionated igneous rocks curated GSJ and USGS and some highly fractionated granites with extremely large Eu negative anomaly were determined by MC-ICP-MS using Sm internal standardization methods. The degree of Eu isotope fractionation (δ153/151Eu) was calculated on the basis of NIST3117a Eu standard. All of highly fractionated igneous rocks in this study showed that their 153Eu/151Eu values are higher than NIST3117a Eu standard, indicating that 151Eu isotope was enriched in the felsic magma. Our results suggest that a study for Eu isotope fractionation from highly fractionated granites and high silica rhyolite will provide a valuable key for understanding geochemical processes related with magmatic differentiation processes.