GHR1 Zircon – A New Eocene Natural Reference Material for Microbeam U-Pb Geochronology and Hf Isotopic Analysis of Zircon

Michael P. Eddy, Mauricio Ibañez-Mejia, Seth D. Burgess, Matthew A. Coble, Umberto G. Cordani, Joel DesOrmeau, George E Gehrels, Xianhua Li, Scott MacLennan, Mark Pecha, Kei Sato, Blair Schoene, Victor A. Valencia, Jeffrey D. Vervoort, Tiantian Wang

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

We present multitechnique U-Pb geochronology and Hf isotopic data from zircon separated from rapakivi biotite granite within the Eocene Golden Horn batholith in Washington, USA. A weighted mean of twenty-five Th-corrected 206Pb/238U zircon dates produced at two independent laboratories using chemical abrasion-isotope dilution-thermal ionisation mass spectrometry (CA-ID-TIMS) is 48.106 ± 0.023 Ma (2s analytical including tracer uncertainties, MSWD = 1.53) and is our recommended date for GHR1 zircon. Microbeam 206Pb/238U dates from laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and secondary ion mass spectrometry (SIMS) laboratories are reproducible and in agreement with the CA-ID-TIMS date to within < 1.5%. Solution multi-collector ICP-MS (MC-ICP-MS) measurements of Hf isotopes from chemically purified aliquots of GHR1 yield a mean 176Hf/177Hf of 0.283050 ± 17 (2s, n = 10), corresponding to a εHf0 of +9.3. Hafnium isotopic measurements from two LA-ICP-MS laboratories are in agreement with the solution MC-ICP-MS value. The reproducibility of 206Pb/238U and 176Hf/177Hf ratios from GHR1 zircon across a variety of measurement techniques demonstrates their homogeneity in most grains. Additionally, the effectively limitless reserves of GHR1 material from an accessible exposure suggest that GHR1 can provide a useful reference material for U-Pb geochronology of Cenozoic zircon and Hf isotopic measurements of zircon with radiogenic 176Hf/177Hf.

Original languageEnglish (US)
JournalGeostandards and Geoanalytical Research
DOIs
StateAccepted/In press - Jan 1 2018

Keywords

  • Hf isotope ratios
  • ID-TIMS
  • LA-ICP-MS
  • MC-ICP-MS
  • reference material
  • secondary ion mass spectrometry
  • U-Pb geochronology
  • zircon

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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    Eddy, M. P., Ibañez-Mejia, M., Burgess, S. D., Coble, M. A., Cordani, U. G., DesOrmeau, J., Gehrels, G. E., Li, X., MacLennan, S., Pecha, M., Sato, K., Schoene, B., Valencia, V. A., Vervoort, J. D., & Wang, T. (Accepted/In press). GHR1 Zircon – A New Eocene Natural Reference Material for Microbeam U-Pb Geochronology and Hf Isotopic Analysis of Zircon. Geostandards and Geoanalytical Research. https://doi.org/10.1111/ggr.12246