U‐Pb Detrital Zircon Analysis – Results of an Inter‐laboratory Comparison

Inter-laboratory comparison of laser ablation ICP-MS and SIMS U-Pb dating of synthetic detrital zircon samples provides an insight into the state-of-the art of sedimentary provenance studies. Here, we report results obtained from ten laboratories that routinely perform this type of work. The achieved level of bias was mostly within ± 2% relative to the ID-TIMS U-Pb ages of zircons in the detrital sample, and the variation is likely to be attributed to variable Pb/U elemental fractionation due to zircon matrix differences between the samples and the reference materials used for standardisation. It has been determined that ~ 5% age difference between adjacent age peaks is currently at the limit of what can be routinely resolved by the in situ dating of detrital zircon samples. Precision of individual zircon age determination mostly reflects the data reduction and procedures of measurement uncertainty propagation, and it is largely independent of the instrumentation, analytical technique and reference samples used for standardisation. All laboratories showed a bias towards selection of larger zircon grains for analysis. The experiment confirms the previously published estimates of the minimum number of grains that have to be analysed in order to detect minor zircon age populations in detrital samples. Une comparaison inter-laboratoires de datation U-Pb d'echantillons de zircons detritiques de synthese par les methodes d'ablation laser ICP-MS et SIMS donne un apercu de l'etat de l'art des etudes de provenance sedimentaire. Nous presentons ici les resultats obtenus par dix laboratoires qui effectuent regulierement ce type de travail. Le niveau de biais atteint etait compris dans l'intervalle ± 2% par rapport aux âges U-Pb ID-TIMS des zircons de l'echantillon detritique et la variation peut certainement etre attribue a un fractionnement elementaire Pb/U variable relie a des differences de matrices entre les zircons des echantillons et les zircons de reference utilises pour la normalisation. Il a ete determine qu'environ 5% de difference d'âge entre les pics d'âge adjacents est actuellement a la limite de ce qui peut etre resolu en mode routine par la datation in situ d'echantillons de zircons detritiques. La precision de la determination de l'âge de zircon individuel reflete principalement la reduction des donnees et les procedures de mesure de la propagation de l'incertitude, et elle est largement independante de l'instrumentation, de la technique d'analyse et des echantillons de reference utilises pour la standardisation. Tous les laboratoires ont montre un biais vers la selection des plus gros grains de zircon pour l'analyse. L'experience confirme les estimations precedemment publiees sur le nombre minimum de grains qui doivent etre analyses afin de detecter les populations mineures d'âge de zircons dans les echantillons detritiques.

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