Spot zircon U-Pb isotope analysis by ICP-MS coupled with a frequency quintupled (213 nm) Nd-YAG laser system

Abstract

A method for precise determination of 207Pb/206Pb and 206Pb/238U ratios of zircon was developed, using an ICP-MS with 213 nm Nd-YAG laser ablation system. Compared with the conventional 266 nm laser, the 213 nm laser has advantages of high absorption of energy and effective reduction of U-Pb elemental fractionation. The maximum fractionation during the first 80 seconds is about 1.3 times the initial value. In addition, by using a linear fit of 206Pb/238U ratios acquired during a depth profile analysis, U-Pb elemental fractionation can be further corrected and the precision of 206Pb/238U ratio measurement is improved to around 3% (2σ). © 2004 by The Geochemical Society of Japan.