Articles | Volume 8, issue 4
https://doi.org/10.5194/gchron-8-679-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gchron-8-679-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
29 Oct 2026
Research article |
| 29 Oct 2026
| 29 Oct 2026
Analytical strategies for 207Pb ∕ 235U carbonate geochronology
Dawid Szymanowski
CORRESPONDING AUTHOR
Department of Earth and Planetary Sciences, ETH Zurich, 8092 Zurich, Switzerland
Marcel Guillong
Department of Earth and Planetary Sciences, ETH Zurich, 8092 Zurich, Switzerland
Pieter Vermeesch
Department of Earth Sciences, University College London, London WC1E 6BT, United Kingdom
Philip J. Hopley
School of Natural Sciences, Birkbeck, University of London, London WC1E 7HX, United Kingdom
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Alyssa J. McKanna, Blair Schoene, and Dawid Szymanowski
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Secondary ion mass spectrometry (SIMS) is the oldest and most sensitive analytical technique for in situ U–Pb geochronology. This paper introduces a new algorithm for SIMS data reduction that treats data as
compositional data, which means that the relative abundances of 204Pb, 206Pb, 207Pb, and 238Pb are processed within a tetrahedral data space or
simplex. The new method is implemented in an eponymous computer programme that is compatible with the two dominant types of SIMS instruments.
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Short summary
U–Pb geochronology of carbonates using 238U and 206Pb can be inaccurate beyond ca. 1.5 Ma. This paper explores analytical strategies to use the more accurate, alternative approach using 235U and 207Pb. Solution mode and laser ablation analyses of reference materials and of a southern African speleothem demonstrate that this method is widely applicable, improving the ability to provide accurate carbonate chronologies, particularly in the freshwater realm.
U–Pb geochronology of carbonates using 238U and 206Pb can be inaccurate beyond ca. 1.5 Ma. This...
