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Matrix effects in Pb/U measurements during LA-ICP-MS analysis of the mineral apatite
journal contribution
posted on 2023-05-18, 20:28 authored by Thompson, J, Sebastien MeffreSebastien Meffre, Maas, R, Vadim Kamenetsky, Maya KamenetskyMaya Kamenetsky, Karsten GoemannKarsten Goemann, Ehrig, K, Leonid DanyushevskyU–Pb ages of several apatite reference materials, acquired by LA-ICP-MS over a 3.5 year period using the Otter Lake apatite as a primary standard, show systematic offsets (up to 3%) from reference ages obtained by isotope dilution mass spectrometry. The offsets are well outside known analytical errors from counting statistics, uncertainty in common Pb corrections or excess 206Pb in high-Th/U materials. The age offsets also do not correlate strongly with the concentrations of F, Cl, REE, Th and U, with accumulated radiation dose or with the depth of ablation pits. We suggest that the observed age offsets are related to elemental fractionation at the ablation site, but their direction and magnitude cannot at present be predicted from compositional differences in different apatite samples. Our results further suggest that Otter Lake apatite is too heterogeneous for use as a calibration standard. Two other apatite samples, OD306 (1596.7 ± 7.1 Ma) and the 401 apatite (530.3 ± 1.5 Ma) are introduced as potential U–Pb reference materials.
Funding
Australian Research Council
History
Publication title
Journal of Analytical Atomic SpectrometryVolume
31Issue
6Pagination
1206-1215ISSN
0267-9477Department/School
School of Natural SciencesPublisher
Royal Society of ChemistryPlace of publication
UKRights statement
Copyright 2016 The Royal Society of ChemistryRepository Status
- Restricted