Developing state-of-the-art analytical techniques for high-precision U-Pb dating

Performance of the IsotopX PHOENIX thermal ionisation mass spectrometer for high-precision U-Pb geochronology, since 2016

The new mass spectrometer is equipped with a highly sensitive and linear Daly ion counting system and high-resistance 10E12 Ohm Faraday cups for low-level multicollection of small Pb and U ion beams. It is operational since September 2016 and delivers U-Pb dates of 0.02 to 0.01% internal precision in 206Pb/238U age.

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High-precision U and Pb isotopic measurements of synthetic ET100 EARTHTIME solution on both TIMS at University of Geneva

Our precision and reproducibility of zircon U-Pb dating using chemical-abrasion, isotope-dilution, thermal ionisation mass spectrometry. are at the forefront of geochronology and are constantly improved. For most recent developments see Schaltegger et al. (2015a and b). The 206Pb/238U date of the synthetic EARTHTIME solution ET100 (nominal apparent age of around 100 Ma) is constantly monitored on both Phoenix and Triton mass spectrometers. The diagram below shows perfect coincidence of results between Pb Daly/U 1E12 Ohm faraday on Phoenix, Pb faraday/U faraday on Phoenix and Pb SEM/U 1E12 Ohm faraday measurement protocols on Triton. The intercalibration is regularly checked every 12 months, and continues to yield the same perfect coincidence since the Triton TIMS has been upgraded with 1E13 Ohm resistance amplifiers in 2018.These results have been presented at Goldschmidt Conference 2018 in Boston (Schaltegger, 2018) and are subject to a scientific publication in an international journal.

 

Davies J.H.F.L., Bouvier A.-S., Baumgartner L.P., Vennemann T.W. & Schaltegger U. (2015) Progress towards using oxygen isotopes in baddeleyite to assess Pb loss. Goldschmidt Conference 2015, Prague, 16-21. 8. 2015

Schaltegger U. (2018) Heading towards the most precise, accurate and reproducible U-Pb age of least material. Goldschmidt Conference, 12-17. 8. 2018, Boston

Schaltegger U., Schmitt A. & Horstwood M. (2015) U-Th-Pb zircon geochronology by ID-TIMS, SIMS and laser ablation ICP-MS: recipes, interpretations and opportunities. Invited review Chem Geol., 402, 89-110

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