NanoSIMS Pb/Pb dating of tranquillityite in high-Ti lunar basalts: Implications for the chronology of high-Ti volcanism on the Moon

Romain Tartèse, Mahesh Anand, Thomas Delhaye

    Research output: Contribution to journalArticlepeer-review

    Abstract

    In this study, we carried out Pb/Pb dating of tranquillityite in high-Ti mare basalts 10044, 75055, and 74255, using a Cameca NanoSIMS 50 at a spatial resolution of ∼3 μm. The analyses yielded 207Pb/ 206Pb dates of 3722 ± 11 Ma for sample 10044, 3772 ± 9 Ma for sample 75055, and 3739 ± 10 Ma for sample 74255, at 95% confidence level. These dates are consistent with previously determined crystallization and emplacement ages of these samples using different radiogenic systems. These high-precision ages allow refinement of the timing of some of the high-Ti basaltic volcanism on the Moon. Crystallization ages of three different high-Ti basalt units, integrating these new Pb/Pb ages with previous Rb-Sr and Sm-Nd age determinations, are consistent with previous estimates but associated with uncertainties 3 to 5 times lower. In addition, the data obtained in this study confirm that tranquillityite contains very low amounts of initial common Pb and has a high-Pb ionization efficiency, making it an excellent candidate for Pb/Pb dating by ion microprobe. The higher spatial resolution afforded by NanoSIMS 50 and the recent discovery of tranquillityite in several terrestrial mafic rocks opens up a new area of research allowing an independent and rapid age dating of basaltic rocks in polished sections.

    Original languageEnglish
    Pages (from-to)1477-1486
    Number of pages10
    JournalThe American Mineralogist
    Volume98
    Issue number8-9
    DOIs
    Publication statusPublished - Aug 2013

    Keywords

    • High-Ti mare basalts
    • Ion probe
    • NanoSIMS 50
    • Pb/Pb dating
    • Tranquillityite

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