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

Author(s): Nasdala, Lutz; Corfu, Fernando; Schoene, Blair; Tapster, Simon R; Wall, Corey J; et al

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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.
Publication Date: 30-Aug-2018
Citation: Nasdala, Lutz, Fernando Corfu, Blair Schoene, Simon R. Tapster, Corey J. Wall, Mark D. Schmitz, Maria Ovtcharova et al. "GZ 7 and GZ 8–Two Zircon Reference Materials for SIMS U‐Pb Geochronology." Geostandards and Geoanalytical Research 42, no. 4 (2018): 431-457. doi:10.1111/ggr.12239.
DOI: doi:10.1111/ggr.12239
ISSN: 1639-4488
EISSN: 1751-908X
Pages: 431 - 457
Language: eng
Type of Material: Journal Article
Journal/Proceeding Title: Geostandards and Geoanalytical Research
Version: Final published version. This is an open access article.

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