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

Ninna K. Jensen*, Zhengbin Deng, James N. Connelly, Martin Bizzarro

*Corresponding author for this work

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Abstract

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 91Zr-96Zr 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 δ94ZrIPGP-Zr values (deviation of the 94Zr/90Zr ratio in the sample relative to the IPGP-Zr reference material) and associated intermediate precisions (2s) for the zircon reference materials 91500, Mud Tank, Plešovice and Penglai of -0.041 ± 0.015‰, 0.018 ± 0.013‰, 0.089 ± 0.020‰ and -0.117 ± 0.021‰, respectively. Furthermore, this method yields un-biased δ94ZrIPGP-Zr and 176Hf/177Hf results for 25-ng Zr and 0.56-ng Hf aliquots of the Mud Tank zircon with intermediate precisions (2s) of 0.027‰ and 1.7 ε (parts per ten thousand), respectively. Thus, the presented method is applicable for the analysis of extremely small and rare zircon grains.

Original languageEnglish
JournalGeostandards and Geoanalytical Research
Volume48
Issue number1
Pages (from-to)5-28
Number of pages24
ISSN1639-4488
DOIs
Publication statusPublished - 2024

Bibliographical note

Publisher Copyright:
© 2023 The Authors. Geostandards and Geoanalytical Research published by John Wiley & Sons Ltd on behalf of International Association of Geoanalysts.

Keywords

  • Hf isotopes
  • MC-ICP-MS
  • stable Zr isotopes
  • zircon reference material
  • Zr double spike

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