Synthetic zircon doped with hafnium and rare earth elements: A reference material for in situ hafnium isotope analysis

Christopher M. Fisher, John M. Hanchar, Scott D. Samson, Bruno Dhuime, Janne Blichert-Toft, Jeffery D. Vervoort, Rebecca Lam

Research output: Contribution to journalArticle

87 Scopus citations

Abstract

A series of flux-grown synthetic zircon crystals doped with Hf and selected rare earth elements (REE) were produced for use as a potential reference material for Lu-Hf isotopic analysis of zircon by in situ laser ablation multi-collector inductively-coupled plasma mass spectrometry (LA-MC-ICPMS). The synthetic zircon crystals were doped such as to produce a large range of REE/Hf, allowing for a robust means of monitoring and correcting the sometimes large 176Yb and 176Lu isobaric interferences on the low-abundance 176Hf in natural zircon, as well as potential oxide interferences from Gd, Tb, and Dy. The synthetic zircon crystals have a homogeneous Hf isotopic composition, both within and between grains, as documented by solution MC-ICPMS analyses of Hf chemically separated from multiple fragments of zircon from three different syntheses, and 321 laser ablation MC-ICPMS analyses done in two different laboratories. An additional 110 in situ analyses of natural zircon crystals reveal identical behavior of natural and synthetic zircon during Hf isotope analysis by laser ablation. Hence, the synthetic zircon crystals provide a means of monitoring a wide range of Yb and Lu interferences (up to 50% of the total signal intensity at mass 176) during routine isotopic analysis for geological studies. They also may be helpful in developing improved laboratory protocols for accurate in situ Lu-Hf isotopic measurement of natural zircon. The present data illustrate the importance of the 176Yb interference correction on 176Hf, which can result in large biases if not properly applied to natural samples with their variable and often high 176Yb/177Hf. This study definitively shows that use of high-REE/Hf synthetic zircon standards for calibrating the Yb mass bias correction is more accurate than use of Yb-doped natural Hf solutions. Finally, the results of the present work suggest that synthetic minerals may prove useful as both in situ method development tools and isotopic reference materials.

Original languageEnglish (US)
Pages (from-to)32-47
Number of pages16
JournalChemical Geology
Volume286
Issue number1-2
DOIs
StatePublished - Jun 26 2011

Keywords

  • Hafnium isotopes
  • Isobaric interference
  • Laser ablation
  • Reference material
  • Synthetic zircon
  • Ytterbium

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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