The McClure Mountain Syenite Apatite as a Potential Age Control Reference Material for LA-ICP-MS AFT and U-Pb Double Dating

Abstract

Apatite fission track (AFT) dating is now routinely performed using LA-ICP-MS, and U-Pb age data are often acquired at the same time, allowing double dating of individual grains. Furthermore, additional geochemical data, such as REE mass fractions are readily acquired during the analysis. It is therefore of practical interest to identify a single material as a quality control on ages and composition. Here we present AFT and U-Pb data for the McClure Mountain Syenite (MMS) apatite, already widely used as an age reference material by the U-Pb community. We performed double dating on 238 grains, in thirteen measurement sessions over two years. The AFT data show remarkable reproducibility with an overall central age of 254.1 ± 5.1 Ma. The U-Pb results agree with the reference age for individual sessions (and for all data together). The results show that that the McClure Mountain apatite is a valid quality control material for double dating, allowing the use of the same material for both methods. We also propose to extend the quality control using MMS to trace element measurements performed in conjunction AFT and U-Pb dating.