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 N., Martin Ende, John W. Valley, Michael J. Spicuzza & 2 others Bhuwadol Wanthanachaisaeng, Gerald Giester

*Corresponding author for this work

Research output: Contribution to journalArticle

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Abstract

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 mean 206Pb/ 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)431-457
Number of pages27
JournalGeostandards and Geoanalytical Research
Volume42
Issue number4
DOIs
Publication statusPublished - Dec 2018

Bibliographical note

Copyright the Author(s) 2018. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • zircon
  • reference material
  • SIMS
  • U-Pb geochronology
  • Ti-in-zircon geothermometry
  • NATURAL ZIRCON
  • SINGLE ZIRCONS
  • HF ISOTOPE MEASUREMENTS
  • ENERGY-LEVELS
  • TI-IN-ZIRCON
  • MASS-SPECTROMETRY
  • LU-HF
  • RADIATION-DAMAGE
  • HALF-LIVES
  • HIGH-PRECISION

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    Nasdala, L., Corfu, F., Schoene, B., Tapster, S. R., Wall, C. J., Schmitz, M. D., ... Giester, G. (2018). GZ7 and GZ8 – two zircon reference materials for SIMS U-Pb geochronology. Geostandards and Geoanalytical Research, 42(4), 431-457. https://doi.org/10.1111/ggr.12239