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A Critical Evaluation of U–Pb Calibration Schemes Used in SIMS Zircon Geochronology
Author(s) -
Jeon Heejin,
Whitehouse Martin J.
Publication year - 2015
Publication title -
geostandards and geoanalytical research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.037
H-Index - 73
eISSN - 1751-908X
pISSN - 1639-4488
DOI - 10.1111/j.1751-908x.2014.00325.x
Subject(s) - zircon , geochronology , calibration , analytical chemistry (journal) , geology , calibration curve , mineralogy , chemistry , geochemistry , physics , detection limit , environmental chemistry , chromatography , quantum mechanics
Precision and accuracy in SIMS zircon geochronology strongly depend on the method of determination of the interelement ion ratios (e.g., 206 Pb/ 238 U) from the measured secondary ion ratios ( 206 Pb + / 238 U + ). Six possible U–Pb calibrations (Pb/U– UO 2 /U, Pb/U– UO /U, Pb/U– UO 2 / UO , Pb/ UO – UO 2 /U, Pb/ UO – UO /U, Pb/ UO – UO 2 / UO ) based on simple power law relationships, and Pb/ UO 2 ‐related one‐ and two‐ (a power law) dimensional ones were compared using data acquired on the 91500 zircon reference material from one hundred measurement sessions, to determine the most statistically reliable scheme. Taking advantage of U oxide species ( UO and UO 2 ) over atomic U, due to their similar energy distribution to Pb and higher intensities, the data calibrated with Pb/ UO – UO 2 / UO showed the smallest mean uncertainties and dispersions, and provided the best‐fit calibration curve consistently. Although it was demonstrated with Temora 2 that the unknown zircon age was not changed significantly by different calibrations, its precision could be improved using the Pb/ UO – UO 2 / UO calibration in zircon geochronology.