Publication: GZ7 and GZ8 – Two Zircon Reference Materials for SIMS U-Pb Geochronology
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Issued Date
2018
Resource Type
File Type
application/pdf
ISSN
16394488
Other identifier(s)
2-s2.0-85054508859
Rights Holder(s)
มหาวิทยาลัยศรีนครินทรวิโรฒ
Bibliographic Citation
Geostandards and Geoanalytical Research. Vol 42, No.4 (2018), p.431-457
Suggested Citation
Nasdala L., Corfu F., Schoene B., Tapster S.R., Wall C.J., Schmitz M.D., Ovtcharova M., Schaltegger U., Kennedy A.K., Kronz A., Reiners P.W., Yang Y.-H., Wu F.-Y., Gain S.E.M., Griffin W.L., Szymanowski D., Chanmuang N. C., Ende M., Valley J.W., Spicuzza M.J., Wanthanachaisaeng B., Giester G. GZ7 and GZ8 – Two Zircon Reference Materials for SIMS U-Pb Geochronology. Geostandards and Geoanalytical Research. Vol 42, No.4 (2018), p.431-457. doi:10.1111/ggr.12239 Retrieved from: https://hdl.handle.net/20.500.14740/5782
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. © 2018 The Authors. Geostandards and Geoanalytical Research published by John Wiley & Sons Ltd on behalf of International Association of Geoanalysts