Research Article| October 01, 2013 Globally synchronous Marinoan deglaciation indicated by U-Pb geochronology of the Cottons Breccia, Tasmania, Australia C.R. Calver; C.R. Calver 1Mineral Resources Tasmania, PO Box 56, Rosny Park, Tasmania 7018, Australia Search for other works by this author on: GSW Google Scholar J.L. Crowley; J.L. Crowley 2Department of Geosciences, Boise State University, 1910 University Drive, Boise, Idaho 83725-1535, USA Search for other works by this author on: GSW Google Scholar M.T.D. Wingate; M.T.D. Wingate 3Geological Survey of Western Australia, 100 Plain Street, East Perth, Western Australia 6004, Australia4School of Earth and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia Search for other works by this author on: GSW Google Scholar D.A.D. Evans; D.A.D. Evans 5Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06520-8109, USA Search for other works by this author on: GSW Google Scholar T.D. Raub; T.D. Raub 6Department of Earth and Environmental Sciences, University of St Andrews, St Andrews, KY16 9AL Scotland, UK Search for other works by this author on: GSW Google Scholar M.D. Schmitz M.D. Schmitz 2Department of Geosciences, Boise State University, 1910 University Drive, Boise, Idaho 83725-1535, USA Search for other works by this author on: GSW Google Scholar Author and Article Information C.R. Calver 1Mineral Resources Tasmania, PO Box 56, Rosny Park, Tasmania 7018, Australia J.L. Crowley 2Department of Geosciences, Boise State University, 1910 University Drive, Boise, Idaho 83725-1535, USA M.T.D. Wingate 3Geological Survey of Western Australia, 100 Plain Street, East Perth, Western Australia 6004, Australia4School of Earth and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia D.A.D. Evans 5Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06520-8109, USA T.D. Raub 6Department of Earth and Environmental Sciences, University of St Andrews, St Andrews, KY16 9AL Scotland, UK M.D. Schmitz 2Department of Geosciences, Boise State University, 1910 University Drive, Boise, Idaho 83725-1535, USA Publisher: Geological Society of America Received: 14 Mar 2013 Revision Received: 19 Jun 2013 Accepted: 27 Jun 2013 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2013 Geological Society of America Geology (2013) 41 (10): 1127–1130. https://doi.org/10.1130/G34568.1 Article history Received: 14 Mar 2013 Revision Received: 19 Jun 2013 Accepted: 27 Jun 2013 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation C.R. Calver, J.L. Crowley, M.T.D. Wingate, D.A.D. Evans, T.D. Raub, M.D. Schmitz; Globally synchronous Marinoan deglaciation indicated by U-Pb geochronology of the Cottons Breccia, Tasmania, Australia. Geology 2013;; 41 (10): 1127–1130. doi: https://doi.org/10.1130/G34568.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract U-Pb zircon data from the uppermost Cottons Breccia, representing the Marinoan glacial-postglacial 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. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.