Scientific article

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

Published inGeostandards and Geoanalytical Research, vol. 42, no. 4, p. 431-457
Publication date2018

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 3 1018 g-1 (GZ7) and 2.53 3 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 lg g-1 (GZ7) and 1305 lg 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 lg g-1 ± 0.18 lg g-1; 95% confidence uncertainty) may prove useful as reference material for Ti-in-zircon temperature estimates.

  • Zircon
  • Reference material
  • U-Pb
Citation (ISO format)
NASDALA, Lutz et al. GZ7 and GZ8 - Two Zircon Reference Materials for SIMS U-Pb Geochronology. In: Geostandards and Geoanalytical Research, 2018, vol. 42, n° 4, p. 431–457. doi: 10.1111/ggr.12239
Main files (1)
Article (Published version)
ISSN of the journal1639-4488

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