Rapid U-Pb Geochronology by Laser Ablation Multi-Collector ICP-MS

Detrital zircon (DZ) U-Pb laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) has revolutionised the way geologists approach many Earth science questions. Although recent research has focused on rapid sample throughput, acquisition rates are limited to 100–300 analyses h⁻¹. We present a method to acquire zircon U-Pb dates at rates of 120, 300, 600 and 1200 analyses h⁻¹ (30, 12, 6 and 3 s per analysis) by multi-collector LA-ICP-MS. We demonstrate the efficacy of this method by analysing twelve zircon reference materials with dates from ~ 3465 to ~ 28 Ma. Mean offset from high-precision dates increases with faster rates from 0.9% to 1.1%; mean random 1s uncertainty increases from 0.6% to 1.3%. We tested this new method on a sandstone sample previously characterised by large-n DZ geochronology. Quantitative comparison shows increased correspondence among age distributions comprising > 300 dates. This new method holds promise for DZ geochronology because (a) it requires no major changes to hardware, but rather modifications to software; (b) it yields robust age distributions well-suited for quantitative analysis and maximum depositional age calculations; (c) there is only a minor sacrifice of accuracy and measurement uncertainty; and (d) there is less burden to researchers in terms of time investment and analytical cost.