S9: 40Ar/39Ar dating

The 40Ar/39Ar dating: historical perspective and recent advances

Sébastien Nomade,
Laboratoire des Sciences du Climat et de l’Environnement, UMR 8212, Université Versailles Saint-Quentin et Paris-Saclay,

Web Lecture on February 17,  2022 at 3:00 PM (Paris Time)

Since the pioneer work of Merrihue and Turner in 1966, the 40Ar/39Ar method have become one of the most used and abused radio-isotopic dating methods applied in Geosciences. In 1998 the first complete work of intercalibration of flux standards by Renne and collaborators have put the first stone toward high accuracy 40Ar/39Ar dating. Over the first decade of 2000’s the works of Min and collaborators (2000); Kuiper and collaborators (2008) and Renne et al., (2011) for examples have allowed major improvements of both the standards and K total decay constant decay constant accuracy and precision. The Earthtime consortium efforts as well as continuous technological innovations that have led to new generation of noble gas mass spectrometers equipped with high-sensitivity multicollector arrays allow today to measure, smaller quantities of material with unprecedented precision. After decades of discussions, in 2021, the 40Ar/39Ar community successfully achieved thank to a large international consensus (i.e. 35 laboratories involved) the publication of an article entitled “Interpreting and reporting 40Ar/39Ar geochronologic data” (Shaen et al., 2021) that is now the international reference of good practices. After a short but thorough review of the history and current practices of the 40Ar/39Ar dating method. I will illustrate using several examples taken in the recent literature the state of the art and limits of this method to geosciences in general and stratigraphy in particular.
Merrihue and Turner (1966). J. Geophys. Res. https://doi.org/10.1029/JZ071i011p02852
Renne et al., (1998). Chem. Geol. https://doi.org/10.1016/S0009-2541(97)00159-9
Min et al., (2000). Geochimica Cosmochimica Acta. https://doi.org/10.1016/S0016-7037(99)00204-5
Kuiper et al., (2008). Science. https://doi.org/10.1126/science.1154339
Renne et al., (2011). Geochimica Cosmochimica Acta. https://doi.org/10.1016/j.gca.2011.06.021
Shaen et al., (2021). Geol. Soc. Am. Bull. https://doi.org/10.1130/B35560.1