40Ar/39Ar age of the Lake Saint Martin impact structure (Canada) - Unchaining the Late Triassic terrestrial impact craters

Martin Schmieder, F. Jourdan, Eric Tohver, E.A. Cloutis

    Research output: Contribution to journalArticle

    12 Citations (Scopus)

    Abstract

    © 2014 Elsevier B.V. New 40Ar/39Ar dating of impact-melted K-feldspars and impact melt rock from the ~40 km Lake Saint Martin impact structure in Manitoba, Canada, yielded three plateau ages and one mini-plateau age in agreement with inverse isochron ages for the K-feldspar melt aliquots and a minimum age for a whole-rock impact melt sample. A combination of two plateau ages and one isochron age, with a weighted mean of 227.8±0.9 Ma [±1.1 Ma; including all sources of uncertainty] (2σ MSWD = 0.52; P=0.59), is considered to represent the best-estimate age for the impact. The concordant 40Ar/39Ar ages for the melted K-feldspars, derived from impact melt rocks in the eastern crater moat domain and the partially melted Proterozoic central uplift granite, suggest that the new dates accurately reflect the Lake Saint Martin impact event in the Carnian stage of the Late Triassic. With a relative error of ±0.4% on the 40Ar/39Ar age, the Lake Saint Martin impact structure counts among the most precisely dated impact structures on Earth. The new isotopic age for Lake Saint Martin significantly improves upon earlier Rb/Sr and (U-Th)/He results for this impact structure and contradicts the hypothesis that planet Earth experienced the formation of a giant 'impact crater chain' during a major Late Triassic multiple impact event.
    Original languageEnglish
    Pages (from-to)37-48
    Number of pages12
    JournalEarth and Planetary Science Letters
    Volume406
    Early online date27 Sep 2014
    DOIs
    Publication statusPublished - 15 Nov 2014

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    impact structure
    Canada
    lakes
    craters
    crater
    Lakes
    Triassic
    Rocks
    lake
    impact melts
    Earth (planet)
    melt
    plateaus
    feldspars
    Planets
    rocks
    plateau
    Manitoba
    rock
    Carnian

    Cite this

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    title = "40Ar/39Ar age of the Lake Saint Martin impact structure (Canada) - Unchaining the Late Triassic terrestrial impact craters",
    abstract = "{\circledC} 2014 Elsevier B.V. New 40Ar/39Ar dating of impact-melted K-feldspars and impact melt rock from the ~40 km Lake Saint Martin impact structure in Manitoba, Canada, yielded three plateau ages and one mini-plateau age in agreement with inverse isochron ages for the K-feldspar melt aliquots and a minimum age for a whole-rock impact melt sample. A combination of two plateau ages and one isochron age, with a weighted mean of 227.8±0.9 Ma [±1.1 Ma; including all sources of uncertainty] (2σ MSWD = 0.52; P=0.59), is considered to represent the best-estimate age for the impact. The concordant 40Ar/39Ar ages for the melted K-feldspars, derived from impact melt rocks in the eastern crater moat domain and the partially melted Proterozoic central uplift granite, suggest that the new dates accurately reflect the Lake Saint Martin impact event in the Carnian stage of the Late Triassic. With a relative error of ±0.4{\%} on the 40Ar/39Ar age, the Lake Saint Martin impact structure counts among the most precisely dated impact structures on Earth. The new isotopic age for Lake Saint Martin significantly improves upon earlier Rb/Sr and (U-Th)/He results for this impact structure and contradicts the hypothesis that planet Earth experienced the formation of a giant 'impact crater chain' during a major Late Triassic multiple impact event.",
    author = "Martin Schmieder and F. Jourdan and Eric Tohver and E.A. Cloutis",
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    40Ar/39Ar age of the Lake Saint Martin impact structure (Canada) - Unchaining the Late Triassic terrestrial impact craters. / Schmieder, Martin; Jourdan, F.; Tohver, Eric; Cloutis, E.A.

    In: Earth and Planetary Science Letters, Vol. 406, 15.11.2014, p. 37-48.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - 40Ar/39Ar age of the Lake Saint Martin impact structure (Canada) - Unchaining the Late Triassic terrestrial impact craters

    AU - Schmieder, Martin

    AU - Jourdan, F.

    AU - Tohver, Eric

    AU - Cloutis, E.A.

    PY - 2014/11/15

    Y1 - 2014/11/15

    N2 - © 2014 Elsevier B.V. New 40Ar/39Ar dating of impact-melted K-feldspars and impact melt rock from the ~40 km Lake Saint Martin impact structure in Manitoba, Canada, yielded three plateau ages and one mini-plateau age in agreement with inverse isochron ages for the K-feldspar melt aliquots and a minimum age for a whole-rock impact melt sample. A combination of two plateau ages and one isochron age, with a weighted mean of 227.8±0.9 Ma [±1.1 Ma; including all sources of uncertainty] (2σ MSWD = 0.52; P=0.59), is considered to represent the best-estimate age for the impact. The concordant 40Ar/39Ar ages for the melted K-feldspars, derived from impact melt rocks in the eastern crater moat domain and the partially melted Proterozoic central uplift granite, suggest that the new dates accurately reflect the Lake Saint Martin impact event in the Carnian stage of the Late Triassic. With a relative error of ±0.4% on the 40Ar/39Ar age, the Lake Saint Martin impact structure counts among the most precisely dated impact structures on Earth. The new isotopic age for Lake Saint Martin significantly improves upon earlier Rb/Sr and (U-Th)/He results for this impact structure and contradicts the hypothesis that planet Earth experienced the formation of a giant 'impact crater chain' during a major Late Triassic multiple impact event.

    AB - © 2014 Elsevier B.V. New 40Ar/39Ar dating of impact-melted K-feldspars and impact melt rock from the ~40 km Lake Saint Martin impact structure in Manitoba, Canada, yielded three plateau ages and one mini-plateau age in agreement with inverse isochron ages for the K-feldspar melt aliquots and a minimum age for a whole-rock impact melt sample. A combination of two plateau ages and one isochron age, with a weighted mean of 227.8±0.9 Ma [±1.1 Ma; including all sources of uncertainty] (2σ MSWD = 0.52; P=0.59), is considered to represent the best-estimate age for the impact. The concordant 40Ar/39Ar ages for the melted K-feldspars, derived from impact melt rocks in the eastern crater moat domain and the partially melted Proterozoic central uplift granite, suggest that the new dates accurately reflect the Lake Saint Martin impact event in the Carnian stage of the Late Triassic. With a relative error of ±0.4% on the 40Ar/39Ar age, the Lake Saint Martin impact structure counts among the most precisely dated impact structures on Earth. The new isotopic age for Lake Saint Martin significantly improves upon earlier Rb/Sr and (U-Th)/He results for this impact structure and contradicts the hypothesis that planet Earth experienced the formation of a giant 'impact crater chain' during a major Late Triassic multiple impact event.

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