Laser Ablation ( U‐Th‐Sm )/He Dating of Zircons: Analytical Age Bias and its Consequence for Studying Detrital Zircon Populations - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Article Dans Une Revue Geostandards and Geoanalytical Research Année : 2023

Laser Ablation ( U‐Th‐Sm )/He Dating of Zircons: Analytical Age Bias and its Consequence for Studying Detrital Zircon Populations

Résumé

The in situ (U‐Th‐Sm)/He and U/Pb laser‐ablation double‐dating procedure is a valuable method that can provide a large dataset relatively efficiently in contrast with conventional bulk helium thermochronometry. In this study, we evaluate the potential age error associated with the double ablation procedure and report the in situ (U‐Th‐Sm)/He double‐ablation dating of 249 zircons from the Fish Canyon Tuff locality. With LA‐ICP‐MS pseudo‐depth profiling and 3D numerical modelling, we show that the concentric double‐ablation procedure in minerals with U‐Th‐Sm zoning can generate a significant (U‐Th‐Sm)/He age error (positive or negative), resulting in over‐scattering and/or an offset of the mean age. Pseudo‐depth profiling is insufficient to predict the individual age error, partly because of the superimposed ablations. To evaluate the consequence of this inherent bias, we confront a synthetic age distribution to the error expected for U‐Th‐Sm zoned zircons analysed with double‐ablation (U‐Th‐Sm)/He thermochronometry. As expected, a strong age bias causes the spreading of peak ages, downgrading the original signal. Yet, the throughput of the ablation‐based method can allow intra‐ and inter‐sample peak age identification and comparison, and the coupling of (U‐Th‐Sm)/He and U/Pb ages extends our ability to deconvolute a multimodal age spectrum.
Fichier non déposé

Dates et versions

insu-04360176 , version 1 (21-12-2023)

Identifiants

Citer

Julien Léger, Raphaël Pik, Bouchaïb Tibari, Sébastien Ternois, Mary Ford, et al.. Laser Ablation ( U‐Th‐Sm )/He Dating of Zircons: Analytical Age Bias and its Consequence for Studying Detrital Zircon Populations. Geostandards and Geoanalytical Research, 2023, 47 (2), pp.219-242. ⟨10.1111/ggr.12494⟩. ⟨insu-04360176⟩
25 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More