A Critical Evaluation of U–Pb Calibration Schemes Used in SIMS Zircon Geochronology |
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| Authors: | Heejin Jeon Martin J Whitehouse |
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| Affiliation: | Swedish Museum of Natural History, Stockholm, Sweden |
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| Abstract: | Precision and accuracy in SIMS zircon geochronology strongly depend on the method of determination of the interelement ion ratios (e.g., 206Pb/238U) from the measured secondary ion ratios (206Pb+/238U+). Six possible U–Pb calibrations (Pb/U–UO2/U, Pb/U–UO/U, Pb/U–UO2/UO, Pb/UO–UO2/U, Pb/UO–UO/U, Pb/UO–UO2/UO) based on simple power law relationships, and Pb/UO2‐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 UO2) over atomic U, due to their similar energy distribution to Pb and higher intensities, the data calibrated with Pb/UO–UO2/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–UO2/UO calibration in zircon geochronology. |
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| Keywords: | U– Pb calibration geochronology zircon
SIMS
IMS 1280 calibration U‐Pb gé ochronologie zircon
SIMS
IMS 1280 |
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