@article{59faa23b25fb41d4a2930bae6446bca4,
title = "GZ7 and GZ8 – Two Zircon Reference Materials for SIMS U-Pb Geochronology",
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.",
keywords = "SIMS, Ti-in-zircon geothermometry, U-Pb geochronology, reference material, zircon",
author = "Lutz Nasdala and Fernando Corfu and Blair Schoene and Tapster, {Simon R.} and Wall, {Corey J.} and Schmitz, {Mark D.} and Maria Ovtcharova and Urs Schaltegger and Kennedy, {Allen K.} and Andreas Kronz and Reiners, {Peter W.} and Yang, {Yue Heng} and Wu, {Fu Yuan} and Gain, {Sarah E.M.} and Griffin, {William L.} and Dawid Szymanowski and {Chanmuang N.}, Chutimun and Martin Ende and Valley, {John W.} and Spicuzza, {Michael J.} and Bhuwadol Wanthanachaisaeng and Gerald Giester",
note = "Funding Information: We thank E. Gamini Zoysa (Mincraft Co., Mt. Lavinia) for his awesome assistance in testing and purchasing gem zircon in Sri Lanka. Reference zircon M257 was made available by Wolfgang Hofmeister (Institute of Gemstone Research, Idar-Oberstein and Mainz, Germany), and REE-doped ZrSiO4 crystals were provided by Dominik Talla (University of Vienna). Crystals of U4+-doped ZrSiO4, grown in 1965 by Judith A. Osmer, were loaned by George R. Rossman (California Institute of Technology, Pasadena). Sample preparation was done by Andreas Wagner (University of Vienna), and the high-alloy steel cylinder and piston was machined by Thomas Rosen (University of Vienna). We acknowledge (U-Th)/He analytical assistance from Uttam Chowdhury (University of Arizona, Tucson) and optical absorption measurements by Manfred Wildner (University of Vienna). We thank two anonymous reviewers and journal editor Paul Sylvester for their constructive comments. The SHRIMP II ion microprobe used in this study is operated by a consortium consisting of Curtin University, the University of Western Australia and the Geological Survey of Western Australia. This study used instrumentation funded by the Australian Government, Department of Education, Science and Training (DEST) Systemic Infrastructure Grants, ARC Linkage Infrastructure, Equipment and Facilities (LIEF), Macquarie University and industry partners. This is contribution 1211 from the ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and 1257 from the ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC). Financial support was provided by the Faculty of Geosciences, Geography and Astronomy, University of Vienna, and the Austrian Science Fund (FWF), grant P24448–N19, to L.N. Co-author J.W.V. is supported by the US National Science Foundation (EAR–1524336). Funding Information: We thank E. Gamini Zoysa (Mincraft Co., Mt. Lavinia) for his awesome assistance in testing and purchasing gem zircon in Sri Lanka. Reference zircon M257 was made available by Wolfgang Hofmeister (Institute of Gemstone Research, Idar-Oberstein and Mainz, Germany), and REE-doped ZrSiO4 crystals were provided by Dominik Talla (University of Vienna). Crystals of U4+-doped ZrSiO4, grown in 1965 by Judith A. Osmer, were loaned by George R. Rossman (California Institute of Technology, Pasadena). Sample preparation was done by Andreas Wagner (University of Vienna), and the high-alloy steel cylinder and piston was machined by Thomas Rosen (University of Vienna). We acknowledge (U-Th)/He analytical assistance from Uttam Chowdhury (University of Arizona, Tucson) and optical absorption measurements by Manfred Wildner (University of Vienna). We thank two anonymous reviewers and journal editor Paul Sylvester for their constructive comments. The SHRIMP II ion microprobe used in this study is operated by a consortium consisting of Curtin University, the University of Western Australia and the Geological Survey of Western Australia. This study used instrumentation funded by the Australian Government, Department of Education, Science and Training (DEST) Systemic Infrastructure Grants, ARC Linkage Infrastructure, Equipment and Facilities (LIEF), Macquarie University and industry partners. This is contribution 1211 from the ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and 1257 from the ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC). Financial support was provided by the Faculty of Geosciences, Geography and Astronomy, University of Vienna, and the Austrian Science Fund (FWF), grant P24448?N19, to L.N. Co-author J.W.V. is supported by the US National Science Foundation (EAR?1524336). Publisher Copyright: {\textcopyright} 2018 The Authors. Geostandards and Geoanalytical Research published by John Wiley & Sons Ltd on behalf of International Association of Geoanalysts",
year = "2018",
month = dec,
doi = "10.1111/ggr.12239",
language = "English (US)",
volume = "42",
pages = "431--457",
journal = "Geostandards and Geoanalytical Research",
issn = "1639-4488",
publisher = "Wiley-Blackwell",
number = "4",
}