Accuracy of LA-ICPMS zircon U-Pb age determination: An inter-laboratory comparison |
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| Authors: | Email author" target="_blank">XianHua?LiEmail author XiaoMing?Liu YongSheng?Liu Li?Su WeiDong?Sun HuiQing?Huang Keewook?Yi |
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| Institution: | 1.State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing,China;2.State Key Laboratory of Continental Dynamics, Department of Geology,Northwest University,Xi’an,China;3.State Key Laboratory of Geological Processes and Mineral Resources, Faculty of Earth Sciences,China University of Geosciences,Wuhan,China;4.Geological Lab Center,China University of Geosciences,Beijing,China;5.State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou,China;6.NSW Institute of Frontiers Geoscience, School of Environmental and Life Sciences,University of Newcastle, University Drive,Callaghan,Australia;7.Korea Basic Science Institute,Cheongwon, Chungbuk,Korea |
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| Abstract: | LA-ICPMS zircon U-Pb dating has been greatly advanced and widely applied in the past decade because it is a cheap and fast technique. The internal error of LA-ICPMS zircon U-Pb dating can be better than 1%, but reproducibility (accuracy) is relatively poor. In in order to quantitatively assess the accuracy of this technique, zircons from two dioritic rocks, a Mesozoic dioritic microgranular enclave (FS06) and a Neoproterozoic diorite (WC09-32), were dated independently in eight laboratories using SIMS and LA-ICPMS. Results of three SIMS analyses on FS06 and WC09-2 are indistinguishable within error and give a best estimate of the crystallization age of 132.2 and 760.5 Ma (reproducibility is ～1%, 2RSD), respectively. Zircon U-Pb ages determined by LA-ICPMS in six laboratories vary from 128.3±1.0 to 135.0±0.9 Ma (2SE) for FS06 and from 742.9±3.1 to 777.8±4.7 Ma (2SE) for WC09-32, suggesting a reproducibility of ～4% (2RSD). Uncertainty produced during LA-ICPMS zircon U-Pb analyses comes from multiple sources, including uncertainty in the isotopic ratio measurements, uncertainty in the fractionation factor calculation using an external standard, uncertainty in the age determination as a result of common lead correction, age uncertainty of the external standards and uncertainty in the data reduction. Result of our study suggests that the uncertainty of LA-ICPMS zircon U-Pb dating is approximately 4% (2RSD). The uncertainty in age determination must be considered in order to interpret LA-ICPMS zircon U-Pb data rationally. |
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