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

Year:

2018

Type of Publication:

Artikel

Schlüsselwörter:

zircon, reference material, SIMS, U-Pb geochronology, Ti-in-zircon geothermometry

Autoren:

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

Journal:

Geostandards and Geoanalytical Research

Volume:

42

Nummer:

4

Seiten:

431-457

BibTex:

@article{doi:10.1111/ggr.12239, author = "Lutz Nasdala and Fernando Corfu and Blair Schoene and Simon R. Tapster and Corey J. Wall and Mark D. Schmitz and Maria Ovtcharova and Urs Schaltegger and Allen K. Kennedy and Andreas Kronz and Peter W. Reiners and Yue-Heng Yang and Fu-Yuan Wu and Sarah E. M. Gain and William L. Griffin and Dawid Szymanowski and Chutimun Chanmuang N. and Martin Ende and John W. Valley and Michael J. Spicuzza and Bhuwadol Wanthanachaisaeng and Gerald Giester", 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.", doi = "10.1111/ggr.12239", journal = "Geostandards and Geoanalytical Research", keywords = "zircon, reference material, SIMS, U-Pb geochronology, Ti-in-zircon geothermometry", number = "4", pages = "431-457", title = "{GZ}7 and {GZ}8 – {T}wo {Z}ircon {R}eference {M}aterials for {SIMS} {U}-{P}b {G}eochronolo", url = "https://onlinelibrary.wiley.com/doi/abs/10.1111/ggr.12239", volume = "42", year = "2018", }

Kurzzusammenfassung:

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.