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Plešovice zircon — A new natural reference material for U-Pb and Hf isotopic microanalysis

Sláma, Jiří
Košler, Jan
Condon, Daniel J.
Crowley, James L.
Gerdes, Axel
Hanchar, John M.
Horstwood, Matthew S.A.
Morris, George A.
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Published in Chemical Geology. 2008, vol. 249, no. 1-2, p. 1-35
Abstract Matrix-matched calibration by natural zircon standards and analysis of natural materials as a reference are the principle methods for achieving accurate results in inicrobeam U-Pb dating and Hf isotopic analysis. We describe a new potential zircon reference material for laser ablation ICP-MS that was extracted from a potassic granulite facies rock collected in the southern part of the Bohemian Massif (Plesovice, Czech Republic). Data from different techniques (ID-TIMS, SIMS and LA ICP-MS) and several laboratories suggest that this zircon has a concordant U-Pb age with a weighted mean (206)Pb/(238)U date of 337.13 +/- 0.37 Ma (ID-TIMS, 95% confidence limits, including tracer calibration uncertainty) and U-Pb age homogeneity on the scale used in LA ICP-MS dating. Inhomogeneities in trace element composition due to primary growth zoning prevent its use as a calibration standard for trace element analysis. The content of U varies from 465 ppm in pristine parts of the grains to similar to 3000 ppm in actinide-rich sectors that correspond to pyramidal faces with a high degree of metamictization (present in ca. 30% of the grains). These domains are easily recognized from high intensities on BSE images and should be avoided during the analysis. Hf isotopic composition of the Plesovice zircon (>0.9 wt.% Hf) is homogenous within and between the grains with a mean (176)Hf/(177)Hf value of 0.282492 +/- 0.000013 (2SD). The age and Hf isotopic homogeneity of the Plesovice zircon together with its relatively high U and Pb contents make it an ideal calibration and reference material for laser ablation ICP-MS measurements, especially when using low laser energies and/or small diameters of laser beam required for improved spatial resolution.
Keywords Zircon reference materialLaser ablation ICP-MSPlesoviceU-Pb datingHf isotopesBohemian Massif
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Research group Isotope Geochemistry, Geochronology and Thermochronology
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SLÁMA, Jiří et al. Plešovice zircon — A new natural reference material for U-Pb and Hf isotopic microanalysis. In: Chemical Geology, 2008, vol. 249, n° 1-2, p. 1-35. https://archive-ouverte.unige.ch/unige:21477

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Deposited on : 2012-06-04

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