Issue 3, 2016

High-precision zircon U/Pb geochronology by ID-TIMS using new 1013 ohm resistors

Abstract

Accessory mineral U–Pb geochronology by isotope dilution thermal ionization mass spectrometry (ID-TIMS) requires precise and accurate determinations of parent–daughter isotope ratios. The small sample size, particularly with respect to radiogenic Pb (Pb*), requires highly sensitive ion detection systems. Most studies therefore employ either secondary electron multipliers (SEMs) or Daly photomultipliers that provide low background noise and high sensitivity but have a limited linear range and require dynamic peak-hopping. We here evaluate the application of new 1013 ohm resistors in a Faraday cup amplifier feedback loop for the static collection of all Pb isotopes (sample and tracer) with 202,205,206,207,208Pb measured on Faraday cups and 204Pb measured in the axial SEM of a Thermo Scientific™ TRITON™ Plus TIMS instrument. We demonstrate long-term stability of the amplifier gain calibration using a secondary Nd standard and test short- and long-term stability and reproducibility of amplifier baselines. Accurate calibration of static detector arrays is demonstrated by repeated analyses of synthetic and natural U–Pb standards (ET100, Temora-2 and AUS_Z7_5) with variable Pb* (0.551 to 699 pg) and comparison with conventional dynamic ion counting data. Excellent agreement between the two detector systems for all analysed standards suggests that our static measurement routine with 1013 ohm resistors produces accurate and precise U–Pb isotopic data with superior external reproducibility. We anticipate that this new technique will push the frontiers of high-precision U–Pb geochronology and may represent a crucial advancement in the quest towards inter- and intra-laboratory reproducibility at the 0.01% level.

Graphical abstract: High-precision zircon U/Pb geochronology by ID-TIMS using new 1013 ohm resistors

Supplementary files

Article information

Article type
Paper
Submitted
18 Nov 2015
Accepted
15 Dez 2015
First published
15 Dez 2015

J. Anal. At. Spectrom., 2016,31, 658-665

High-precision zircon U/Pb geochronology by ID-TIMS using new 1013 ohm resistors

A. von Quadt, J. Wotzlaw, Y. Buret, S. J. E. Large, I. Peytcheva and A. Trinquier, J. Anal. At. Spectrom., 2016, 31, 658 DOI: 10.1039/C5JA00457H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements