Title

Plešovice Zircon — A New Natural Reference Material for U–Pb and Hf Isotopic Microanalysis

Document Type

Article

Publication Date

3-30-2008

DOI

http://dx.doi.org/10.1016/j.chemgeo.2007.11.005

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 microbeam 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 (Plešovice, 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 206Pb/238U 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 ~ 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 Plešovice zircon (> 0.9 wt.% Hf) is homogenous within and between the grains with a mean 176Hf/177Hf value of 0.282482 ± 0.000013 (2SD). The age and Hf isotopic homogeneity of the Plešovice 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.

Comments

For full list of authors, please see article.

Copyright Statement

For full list of authors, please see article.

Share

COinS