U-Th/Pb geochronology of detrital zircon and monazite by single shot laser ablation inductively coupled plasma mass spectrometry (SS-LA-ICPMS)

A modified single-shot laser ablation inductively coupled plasma mass spectrometry (SS-LA-ICPMS) technique is presented that enables rapid acquisition of in-situ U-Th/Pb dates on accessory minerals from a single laser pulse. Advances over existing techniques include formulation of a semi-automated data reduction method and robust error propagation. The effects of pulse-to-pulse laser stability and analyte transport configurations on the precision and accuracy of the analyses are systematically assessed. The validity of the SS-LA-ICPMS approach is demonstrated by repeat analyses of multiple zircon and monazite reference materials, which consistently reproduce to within uncertainty of accepted reference values. Application of the method to detrital zircon and monazite samples with a wide range of ages and variable parent and daughter nuclide concentrations results in U-Th/Pb age spectra that are statistically indistinguishable from conventional laser ablation protocols that employ continuous laser pulsing. The SS-LA-ICPMS technique is minimally destructive, offers increased sample and grain throughput and enables rapid dating of large numbers of grains-enabling, e.g., to identify grains that are geologically significant yet rare. (c) 2012 Elsevier B.V. All rights reserved.