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GZ 7 and GZ 8 – Two Zircon Reference Materials for SIMS U‐Pb Geochronology
Author(s) -
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 YueHeng,
Wu FuYuan,
Gain Sarah E. M.,
Griffin William L.,
Szymanowski Dawid,
Chanmuang N. Chutimun,
Ende Martin,
Valley John W.,
Spicuzza Michael J.,
Wanthanachaisaeng Bhuwadol,
Giester Gerald
Publication year - 2018
Publication title -
geostandards and geoanalytical research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.037
H-Index - 73
eISSN - 1751-908X
pISSN - 1639-4488
DOI - 10.1111/ggr.12239
Subject(s) - zircon , geochronology , confidence interval , geology , sri lanka , yield (engineering) , geochemistry , analytical chemistry (journal) , mineralogy , chemistry , materials science , mathematics , environmental chemistry , metallurgy , environmental science , statistics , environmental planning , tanzania
Here, we document a detailed characterisation of two zircon gemstones, GZ 7 and GZ 8. 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 206 Pb/ 238 U ages (95% confidence uncertainty) of 530.26 Ma ± 0.05 Ma ( GZ 7) and 543.92 Ma ± 0.06 Ma ( GZ 8). Neither GZ 7 nor GZ 8 have been subjected to any gem enhancement by heating. Structure‐related parameters correspond well with the calculated alpha doses of 1.48 × 10 18 g −1 ( GZ 7) and 2.53 × 10 18 g −1 ( GZ 8), respectively, and the (U‐Th)/He ages of 438 Ma ± 3 Ma (2 s ) for GZ 7 and 426 Ma ± 9 Ma (2 s ) for GZ 8 are typical of unheated zircon from Sri Lanka. The mean U mass fractions are 680 μg g −1 ( GZ 7) and 1305 μg g −1 ( GZ 8). The two zircon samples are proposed as reference materials for SIMS (secondary ion mass spectrometry) U‐Pb geochronology. In addition, GZ 7 (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.