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

Author(s): Eddy, Michael P; Ibañez-Mejia, Mauricio; Burgess, Seth D; Coble, Matthew A; Cordani, Umberto G; et al

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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.
Publication Date: 2-Nov-2018
Citation: Eddy, Michael P., Mauricio Ibañez‐Mejia, Seth D. Burgess, Matthew A. Coble, Umberto G. Cordani, Joel DesOrmeau, George E. Gehrels et al. "GHR 1 Zircon–A New Eocene Natural Reference Material for Microbeam U‐Pb Geochronology and Hf Isotopic Analysis of Zircon." Geostandards and Geoanalytical Research 43, no. 1 (2019): 113-132. doi:10.1111/ggr.12246.
DOI: doi:10.1111/ggr.12246
ISSN: 1639-4488
EISSN: 1751-908X
Pages: 113 - 132
Type of Material: Journal Article
Journal/Proceeding Title: Geostandards and Geoanalytical Research
Version: Author's manuscript

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