Novel Methods for Concomitant Determination of the Stable Zr Isotope Composition, Lu-Hf Isotope Systematics and U-Pb Age of Individual Zircons

The stable Zr isotope ratios in zircon yield a novel geochemical tracer that, together with the Lu-Hf and U-Pb radiogenic isotope systems, allows for a better understanding of the magmatic evolution of silicate melts. We present a solution-based procedure for coupled stable Zr, Lu-Hf and U-Pb isotope ratio determinations for individual zircons using a Zr-91-Zr-96 tracer purified from Hf and a late-spiking protocol for Zr. This method yields high-precision Zr and Hf isotope results while maintaining low blank levels for U-Pb isotope and Lu/Hf ratio determinations. With a two-fold improvement on the precision relative to previous solution-based work, we report delta Zr-94(IPGP-Zr) values (deviation of the Zr-94/Zr-90 ratio in the sample relative to the IPGP-Zr reference material) and associated intermediate precisions (2s) for the zircon reference materials 91500, Mud Tank, Ple & scaron;ovice and Penglai of -0.041 +/- 0.015 parts per thousand, 0.018 +/- 0.013 parts per thousand, 0.089 +/- 0.020 parts per thousand and -0.117 +/- 0.021 parts per thousand, respectively. Furthermore, this method yields un-biased delta Zr-94(IPGP-Zr) and Hf-176/Hf-177 results for 25-ng Zr and 0.56-ng Hf aliquots of the Mud Tank zircon with intermediate precisions (2s) of 0.027 parts per thousand and 1.7 epsilon (parts per ten thousand), respectively. Thus, the presented method is applicable for the analysis of extremely small and rare zircon grains.