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U-Pb zircon age constraints on late Neoproterozoic glaciation in Tasmania

Calver, Clive; Black, Lance; Everard, John L.; Seymour, David B

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Two new U-Pb dates (sensitive high-resolution ion microprobe on zircon) have an important bearing on the age of the Marinoan (Elatina) glaciation, a presumed global chronostratigraphic marker that has been previously poorly constrained in terms of its numerical age. In the Grassy Group of King Island, intermediate sills dated as 575 ± 3 Ma intrude an Elatina-equivalent diamictite (the Cottons Breccia), cap carbonate, and postglacial shale. The sills are locally vesicular, stratigraphically...[Show more]

dc.contributor.authorCalver, Clive
dc.contributor.authorBlack, Lance
dc.contributor.authorEverard, John L.
dc.contributor.authorSeymour, David B
dc.date.accessioned2015-12-13T23:07:38Z
dc.identifier.issn0091-7613
dc.identifier.urihttp://hdl.handle.net/1885/86299
dc.description.abstractTwo new U-Pb dates (sensitive high-resolution ion microprobe on zircon) have an important bearing on the age of the Marinoan (Elatina) glaciation, a presumed global chronostratigraphic marker that has been previously poorly constrained in terms of its numerical age. In the Grassy Group of King Island, intermediate sills dated as 575 ± 3 Ma intrude an Elatina-equivalent diamictite (the Cottons Breccia), cap carbonate, and postglacial shale. The sills are locally vesicular, stratigraphically limited, probably intruded at shallow depth, and probably closely postdate the end of Marinoan glaciation. In the Togari Group of northwest Tasmania, a rhyodacite flow dated as 582 ± 4 Ma underlies the Croles Hill Diamictite, which is at least partly glaciogenic. No cap carbonate is known from the Croles Hill Diamictite, but in other respects its stratigraphic setting is similar to the Cottons Breccia. The two dates together support a significantly younger age (ca. 580 Ma) for the Marinoan glaciation than some previous estimates, and suggest correlation with the Gaskiers Formation of Newfoundland. The new data cannot exclude the possibility of a ca. 620 Ma age for the Marinoan glaciation, as suggested by recent evidence from outside Australia, but this would require a more complex and much less probable interpretation of the Tasmanian stratigraphic relationships.
dc.publisherGeological Society of America Inc
dc.sourceGeology
dc.subjectKeywords: Neoproterozoic glaciation; Tasmania; Carbonates; Landforms; Lead; Stratigraphy; Uranium; Zircon; Glacial geology; chronostratigraphy; glaciation; Proterozoic; uranium-lead dating; Australasia; Australia; Eastern Hemisphere; Tasmania; World Age determination; Australia; Geochronology; Glaciation; Neoproterozoic; SHRIMP data
dc.titleU-Pb zircon age constraints on late Neoproterozoic glaciation in Tasmania
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume32
dc.date.issued2004
local.identifier.absfor040203 - Isotope Geochemistry
local.identifier.ariespublicationMigratedxPub15127
local.type.statusPublished Version
local.contributor.affiliationCalver, Clive, Mineral Resources Tasmania
local.contributor.affiliationBlack, Lance, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationEverard, John L., Mineral Resources Tasmania
local.contributor.affiliationSeymour, David B, Mineral Resources Tasmania
local.description.embargo2037-12-31
local.bibliographicCitation.issue10
local.bibliographicCitation.startpage893
local.bibliographicCitation.lastpage896
local.identifier.doi10.1130/G20713.1
dc.date.updated2016-02-24T09:47:26Z
local.identifier.scopusID2-s2.0-7444268936
CollectionsANU Research Publications

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