U-Pb dating of zircon by laser ablation ICP-MS: recent improvements and new insights

摘要: A robust method for U-Pb dating of zircon by laser ablation ICP-MS was established using a Thermo-Finnigan Element2 sector field coupled to New Wave UP193HE ArF Excimer system. This included the construction low-volume sample cell and establishment data reduction routine. detailed systematic approach determining optimal settings parameters is presented, which also applicable other instrument set-ups. Laser induced time-dependent elemental fractionation corrected intercept method, whereas drift, mass bias caused ionisation differences are applying external standardisation matrix-matched reference GJ-1. The isobaric interference 204Hg on 204Pb reduced gold trap enabling application an accurate common Pb correction. Typical craters 12, 25 or 35 μm in diameter ca . 20 deep. single analysis takes 65 s automated measurement sequence ensures efficiency. The performance procedure assessed analysing ranging age from Mesoproterozoic Miocene. Concordia ages obtained multiple analyses various well-characterised zircons all within uncertainty accepted values, demonstrating high accuracy method. individual ranges 1 4 % (2σ), depending absolute age, content homogeneity analysed zircon. These results indicate that precision technique presented this study similar those LA-ICP-MS laboratories SIMS analyses.