[SIT22-P30] High precision 182W/183W isotopic compositions of terrestrial samples
Keywords:core-mantle interaction, W isotope, Ocean island basalt, high-precision isotope analysis
In our study, high-precision W isotope ratio measurement with MC-ICP-MS (Thermo co. Ltd., NEPTUNE PLUS) has been developed. We have measured W standard solution (SRM 3163) and obtained the isotopic compositions with a enough high precision of ± 5ppm. However, the standard solution, which separated by cation or anion exchange resin, has systematical 183W/184W drift of -5ppm. These phenomena was also reported by Willbold et al. (2011). Therefore, we corrected the measured W isotope ratios of samples with the standard solution processed by the same method as that of the samples. This technique leads to the reproducible W isotopic compositions with reproducibility of several ppm. We have obtained the negative 182W/183W for the basalts with the high 3He/4He isotopic composition from the Loihi, Hawaii, through the developed analytical method. This result is consitent with that of Mundl et al., (2017). As negative anomaly of 182W/183W could be created by the early earth core segregation, it is probably a signature of core-mantle interaction.