GZ7 and GZ8 – Two Zircon Reference Materials for SIMS U-Pb Geochronology

Lutz Nasdala, Fernando Corfu, Blair Schoene, Simon R. Tapster, Corey J. Wall, Mark D. Schmitz, Maria Ovtcharova, Urs Schaltegger, Allen K. Kennedy, Andreas Kronz, Peter W. Reiners, Yue Heng Yang, Fu Yuan Wu, Sarah E.M. Gain, William L. Griffin, Dawid Szymanowski, Chutimun Chanmuang, Martin Ende, John W. Valley, Michael J. SpicuzzaBhuwadol Wanthanachaisaeng, Gerald Giester

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11 Citations (Scopus)


© 2018 The Authors. Geostandards and Geoanalytical Research published by John Wiley & Sons Ltd on behalf of International Association of Geoanalysts Here, we document a detailed characterisation of two zircon gemstones, GZ7 and GZ8. Both stones had the same mass at 19.2 carats (3.84 g) each; both came from placer deposits in the Ratnapura district, Sri Lanka. The U-Pb data are in both cases concordant within the uncertainties of decay constants and yield weighted mean206Pb/238U ages (95% confidence uncertainty) of 530.26 Ma ± 0.05 Ma (GZ7) and 543.92 Ma ± 0.06 Ma (GZ8). Neither GZ7 nor GZ8 have been subjected to any gem enhancement by heating. Structure-related parameters correspond well with the calculated alpha doses of 1.48 × 1018 g−1(GZ7) and 2.53 × 1018 g−1(GZ8), respectively, and the (U-Th)/He ages of 438 Ma ± 3 Ma (2s) for GZ7 and 426 Ma ± 9 Ma (2s) for GZ8 are typical of unheated zircon from Sri Lanka. The mean U mass fractions are 680 μg g−1(GZ7) and 1305 μg g−1(GZ8). The two zircon samples are proposed as reference materials for SIMS (secondary ion mass spectrometry) U-Pb geochronology. In addition, GZ7 (Ti mass fractions 25.08 μg g−1 ± 0.18 μg g−1; 95% confidence uncertainty) may prove useful as reference material for Ti-in-zircon temperature estimates.
Original languageEnglish
Pages (from-to)431
Number of pages457
JournalGeostandards and Geoanalytical Research
Issue number4
Publication statusPublished - 1 Dec 2018
Externally publishedYes


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