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U-Pb dating of zircon by LA-ICP-MS


Chang, Z and Vervoort, JD and McClelland, WC and Knack, C, U-Pb dating of zircon by LA-ICP-MS, Geochemistry Geophysics Geosystems, 7, (5) Article Q05009. ISSN 1525-2027 (2006) [Refereed Article]


Copyright Statement

Copyright 2006 American Geophysical Union

DOI: doi:10.1029/2005GC001100


In this study we used LA-ICP-MS (laser ablation–inductively coupled plasma–mass spectrometry) to determine U-Pb ages of 5 zircon samples of known age (∼1800 Ma to ∼50 Ma) in order to determine the reproducibility, precision, and accuracy of this geochronologic technique. This work was performed using a ThermoFinnigan Element2 magnetic sector double-focusing ICP-MS coupled with a New Wave Research UP-213 laser system. The laser ablation pit sizes ranged from 30 to 40 μm in diameter. Laser-induced time-dependent fractionation is corrected by normalizing measured ratios in both standards and samples to the beginning of the analysis using the intercept method. Static fractionation, including those caused during laser ablation and due to instrumental discrimination, is corrected using external zircon standards. Total uncertainty for each laser analysis of an unknown is combined quadratically from the uncertainty in the measured isotope ratios of the unknown and the uncertainty in the fractionation factors calculated from the measurement of standards. For individual analyses we estimate that the accuracy and precision are better than 4% at the 2 sigma level, with the largest contribution in uncertainty from the measurement of the standards. Accuracy of age determinations in this study is on the order of 1% on the basis of comparing the weighted average of the LA-ICP-MS determinations to the TIMS ages. Due to unresolved contributions to uncertainty from the lack of a common Pb correction and from potential matrix effects between standards and unknowns, however, this estimate cannot be universally applied to all unknowns. Nevertheless, the results of this study provide an example of the type of precision and accuracy that may be possible with this technique under ideal conditions. In summary, the laser ablation technique, using a magnetic sector ICP-MS, can be used for the U-Pb dating of zircons with a wide range of ages and is a useful complement to the established TIMS and SHRIMP techniques. This technique is especially well suited to reconnaissance geochronologic and detrital zircon studies.

Item Details

Item Type:Refereed Article
Keywords:laser ablation, magnetic sector ICP-MS, U-Pb dating, zircon dating
Research Division:Earth Sciences
Research Group:Geology
Research Field:Mineralogy and crystallography
Objective Division:Mineral Resources (Excl. Energy Resources)
Objective Group:Other mineral resources (excl. energy resources)
Objective Field:Other mineral resources (excl. energy resources) not elsewhere classified
UTAS Author:Chang, Z (Dr Zhaoshan Chang)
ID Code:95367
Year Published:2006
Web of Science® Times Cited:260
Deposited By:Earth Sciences
Deposited On:2014-09-30
Last Modified:2014-11-25
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