U-Pb zircon in situ dating with LA-MC-ICP-MS using a mixed detector configuration

Farid Chemale*, Koji Kawashita, Ivo A. Dussin, Janaína N. Ávila, Dayvisson Justino, Anelise Bertotti

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    59 Citations (Scopus)

    Abstract

    The LA-MC-ICP-MS method applied to U-Pb in situ dating is still rapidly evolving due to improvements in both lasers and ICP-MS. To test the validity and reproducibility of the method, 5 different zircon samples, including the standard Temora-2, ranging in age between 2.2 Ga and 246 Ma, were dated using both LAMC- ICP-MS and SHRIMP. The selected zircons were dated by SHRIMP and, after gentle polishing, the laser spot was driven to the same site or on the same zircon phase with a 213 nm laser microprobe coupled to a multi-collector mixed system. The data were collected with a routine spot size of 25 μm and, in some cases, of 15 and 40 μm. A careful cross-calibration using a diluted U-Th-Pb solution to calculate the Faraday reading to counting rate conversion factors and the highly suitable GJ-1 standard zircon for external calibrations were of paramount importance for obtaining reliable results. All age results were concordant within the experimental errors. The assigned age errors using the LA-MC-ICP-MS technique were, in most cases, higher than those obtained by SHRIMP, but if we are not faced with a high resolution stratigraphy, the laser technique has certain advantages.

    Original languageEnglish
    Pages (from-to)275-295
    Number of pages21
    JournalAnais da Academia Brasileira de Ciencias
    Volume84
    Issue number2
    DOIs
    Publication statusPublished - Jun 2012

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