Globally synchronous marinoan deglaciation indicated by U-Pb geochronology of the cottons Breccia, Tasmania, Australia

C.R. Calver, J.L. Crowley, Michael Wingate, D.A.D. Evans, T.D. Raub, M.D. Schmitz

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    Abstract

    U-Pb zircon data from the uppermost Cottons Breccia, representing the Marinoan glacialpostglacial transition on King Island, Tasmania, provide the first direct age constraint on the Cryogenian-Ediacaran boundary in Australia. Zircons in four samples from the topmost meter of the Cottons Breccia, dated by sensitive high-resolution ion microprobe, exhibit two modes ca. 660 Ma and ca. 635 Ma. The younger component predominates in the uppermost sample, a possibly volcanolithic dolomitic sandstone, apparently lacking glacially transported debris, in the transition to cap carbonate. Chemical abrasion-thermal ionization mass spectrometry (CA-TIMS) U-Pb dating of euhedral zircons from that sample yields a weighted-mean age of 636.41 ± 0.45 Ma. Equivalence to published TIMS ash bed dates from Cryogenian-Ediacaran transitional strata in Namibia (635.51 ± 0.82 Ma, within glacial deposit) and China (635.23 ± 0.84 Ma, 2 m above glacial deposit) supports correlation of those strata to the Australian type sections and globally synchronous deglaciation at the end of the Cryogenian Period. © 2013 Geological Society of America.
    Original languageEnglish
    Pages (from-to)1127-1130
    JournalGeology
    Volume41
    Issue number10
    DOIs
    Publication statusPublished - 2013

    Fingerprint

    deglaciation
    breccia
    geochronology
    cotton
    Ediacaran
    zircon
    glacial deposit
    type section
    ion microprobe
    abrasion
    ionization
    ash
    mass spectrometry
    sandstone
    carbonate

    Cite this

    Calver, C.R. ; Crowley, J.L. ; Wingate, Michael ; Evans, D.A.D. ; Raub, T.D. ; Schmitz, M.D. / Globally synchronous marinoan deglaciation indicated by U-Pb geochronology of the cottons Breccia, Tasmania, Australia. In: Geology. 2013 ; Vol. 41, No. 10. pp. 1127-1130.
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    abstract = "U-Pb zircon data from the uppermost Cottons Breccia, representing the Marinoan glacialpostglacial transition on King Island, Tasmania, provide the first direct age constraint on the Cryogenian-Ediacaran boundary in Australia. Zircons in four samples from the topmost meter of the Cottons Breccia, dated by sensitive high-resolution ion microprobe, exhibit two modes ca. 660 Ma and ca. 635 Ma. The younger component predominates in the uppermost sample, a possibly volcanolithic dolomitic sandstone, apparently lacking glacially transported debris, in the transition to cap carbonate. Chemical abrasion-thermal ionization mass spectrometry (CA-TIMS) U-Pb dating of euhedral zircons from that sample yields a weighted-mean age of 636.41 ± 0.45 Ma. Equivalence to published TIMS ash bed dates from Cryogenian-Ediacaran transitional strata in Namibia (635.51 ± 0.82 Ma, within glacial deposit) and China (635.23 ± 0.84 Ma, 2 m above glacial deposit) supports correlation of those strata to the Australian type sections and globally synchronous deglaciation at the end of the Cryogenian Period. {\circledC} 2013 Geological Society of America.",
    author = "C.R. Calver and J.L. Crowley and Michael Wingate and D.A.D. Evans and T.D. Raub and M.D. Schmitz",
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    Globally synchronous marinoan deglaciation indicated by U-Pb geochronology of the cottons Breccia, Tasmania, Australia. / Calver, C.R.; Crowley, J.L.; Wingate, Michael; Evans, D.A.D.; Raub, T.D.; Schmitz, M.D.

    In: Geology, Vol. 41, No. 10, 2013, p. 1127-1130.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Globally synchronous marinoan deglaciation indicated by U-Pb geochronology of the cottons Breccia, Tasmania, Australia

    AU - Calver, C.R.

    AU - Crowley, J.L.

    AU - Wingate, Michael

    AU - Evans, D.A.D.

    AU - Raub, T.D.

    AU - Schmitz, M.D.

    PY - 2013

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    N2 - U-Pb zircon data from the uppermost Cottons Breccia, representing the Marinoan glacialpostglacial transition on King Island, Tasmania, provide the first direct age constraint on the Cryogenian-Ediacaran boundary in Australia. Zircons in four samples from the topmost meter of the Cottons Breccia, dated by sensitive high-resolution ion microprobe, exhibit two modes ca. 660 Ma and ca. 635 Ma. The younger component predominates in the uppermost sample, a possibly volcanolithic dolomitic sandstone, apparently lacking glacially transported debris, in the transition to cap carbonate. Chemical abrasion-thermal ionization mass spectrometry (CA-TIMS) U-Pb dating of euhedral zircons from that sample yields a weighted-mean age of 636.41 ± 0.45 Ma. Equivalence to published TIMS ash bed dates from Cryogenian-Ediacaran transitional strata in Namibia (635.51 ± 0.82 Ma, within glacial deposit) and China (635.23 ± 0.84 Ma, 2 m above glacial deposit) supports correlation of those strata to the Australian type sections and globally synchronous deglaciation at the end of the Cryogenian Period. © 2013 Geological Society of America.

    AB - U-Pb zircon data from the uppermost Cottons Breccia, representing the Marinoan glacialpostglacial transition on King Island, Tasmania, provide the first direct age constraint on the Cryogenian-Ediacaran boundary in Australia. Zircons in four samples from the topmost meter of the Cottons Breccia, dated by sensitive high-resolution ion microprobe, exhibit two modes ca. 660 Ma and ca. 635 Ma. The younger component predominates in the uppermost sample, a possibly volcanolithic dolomitic sandstone, apparently lacking glacially transported debris, in the transition to cap carbonate. Chemical abrasion-thermal ionization mass spectrometry (CA-TIMS) U-Pb dating of euhedral zircons from that sample yields a weighted-mean age of 636.41 ± 0.45 Ma. Equivalence to published TIMS ash bed dates from Cryogenian-Ediacaran transitional strata in Namibia (635.51 ± 0.82 Ma, within glacial deposit) and China (635.23 ± 0.84 Ma, 2 m above glacial deposit) supports correlation of those strata to the Australian type sections and globally synchronous deglaciation at the end of the Cryogenian Period. © 2013 Geological Society of America.

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