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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 Gordani·Joel DesOrmeau·George E. Gehrels·Xianhua Li·Scott MacLennan·Mark Pecha·Kei Sato·Blair Schoene·Victor A. Valencia·Jeffrey D. Vervoort·Tiantian Wang
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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 206 Pb/ 238 U 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 (2 s analytical including tracer uncertainties, MSWD = 1.53) and is our recommended date for GHR1 zircon. Microbeam 206 Pb/ 238 U 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 176 Hf/ 177 Hf of 0.283050 ± 17 (2 s , n = 10), corresponding to a εHf 0 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 206 Pb/ 238 U and 176 Hf/ 177 Hf 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 176 Hf/ 177 Hf.

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90° N90° S · 180° W ← longitude → 180° E
Source-reported bounding extent: 45.336701909968134° to 59.712097173322924° latitude; -139.04296875° to -120.498046875° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Michael P Eddy, Mauricio Ibañez-Mejia, Seth D. Burgess, Matthew A. Coble, Umberto G Gordani, Joel DesOrmeau, George E. Gehrels, Xianhua Li, Scott MacLennan, Mark Pecha, Kei Sato, Blair Schoene, Victor A. Valencia, Jeffrey D. Vervoort, Tiantian Wang. 2018-12-26. GHR1 Zircon – A new Eocene natural reference material for microbeam U-Pb geochronology and Hf isotopic analysis of zircon. https://doi.org/10.1111/ggr.12246

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