Optimization of Analytical Conditions for LA-ICP-MS and Its Application to Zircon U-Pb Dating

During LA-ICP-MS analysis, the key factor influencing data accuracy of sample analysis is whether the sample can be uniformly delivered from the laser sample chamber to the torch of the ICP-MS.An external container between LA and ICP-MS and a multi-channel rotary sampling cell, which can effectively eliminate the sample position effect during the laser ablation was designed for the study reported in this paper.The pattern of aerosol delivered to ICP-MS is approximately continuous and at the same time, this can greatly improve the stability.Under optimal conditions, using 91500 as external standard, the standard zircons GJ-1, Ple ovice, TEMROA and QH yield U-Pb ages of 604±3 Ma(2δ, MSWD=1.2), 337±1 Ma(2δ, MSWD=1.18), 419±3 Ma(2δ, MSWD=0.15) and 161±1 Ma(2δ, MSWD=0.6), respectively, which agree well with the previously reported ID-TIMS and SHRIMP ages.For the same conditions, using NIST610 as external standard, most trace element results of the glass standards NIST612 and BHVO-2G fall within 10% range of the reference values.The 207Pb/206Pb weighted mean age of zircons from the Tianshan Orogen of Xinjiang is consistent with the previous SHRIMP U-Pb age within uncertainty.This method can effectively reduce the elemental fractionation effects and improve the reliability of the analytical data.