U-Pb geochronology and global context of the Charnian Supergroup, UK: Constraints on the age of key Ediacaran fossil assemblages

Abstract

Research Article| January 01, 2015 U-Pb geochronology and global context of the Charnian Supergroup, UK: Constraints on the age of key Ediacaran fossil assemblages Stephen R. Noble; Stephen R. Noble † 1Natural Environment Research Council Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK †E-mail: srn@bgs.ac.uk. Search for other works by this author on: GSW Google Scholar Daniel J. Condon; Daniel J. Condon 1Natural Environment Research Council Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK Search for other works by this author on: GSW Google Scholar John N. Carney; John N. Carney 2British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK Search for other works by this author on: GSW Google Scholar Philip R. Wilby; Philip R. Wilby 2British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK Search for other works by this author on: GSW Google Scholar Timothy C. Pharaoh; Timothy C. Pharaoh 2British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK Search for other works by this author on: GSW Google Scholar Trevor D. Ford Trevor D. Ford 3Department of Geology, University of Leicester, Leicester, LE1 7RH, UK Search for other works by this author on: GSW Google Scholar Author and Article Information Stephen R. Noble † 1Natural Environment Research Council Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK Daniel J. Condon 1Natural Environment Research Council Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK John N. Carney 2British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK Philip R. Wilby 2British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK Timothy C. Pharaoh 2British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK Trevor D. Ford 3Department of Geology, University of Leicester, Leicester, LE1 7RH, UK †E-mail: srn@bgs.ac.uk. Publisher: Geological Society of America Received: 13 Oct 2013 Revision Received: 06 Jun 2014 Accepted: 21 Jul 2014 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2014 Geological Society of America GSA Bulletin (2015) 127 (1-2): 250–265. https://doi.org/10.1130/B31013.1 Article history Received: 13 Oct 2013 Revision Received: 06 Jun 2014 Accepted: 21 Jul 2014 First Online: 08 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 Stephen R. Noble, Daniel J. Condon, John N. Carney, Philip R. Wilby, Timothy C. Pharaoh, Trevor D. Ford; U-Pb geochronology and global context of the Charnian Supergroup, UK: Constraints on the age of key Ediacaran fossil assemblages. GSA Bulletin 2015;; 127 (1-2): 250–265. doi: https://doi.org/10.1130/B31013.1 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 SocietyGSA Bulletin Search Advanced Search Abstract U-Pb (zircon) ages for key stratigraphic volcanic horizons within the ∼3200-m-thick Ediacaran-age Charnian Supergroup provide an improved age model for the included Avalonian assemblage macrofossils and, hence, temporal constraints essential for intercomparisons of the Charnian fossils with other Ediacaran fossil assemblages globally. The Ives Head Formation (Blackbrook Group), the oldest exposed part of the volcaniclastic Charnian Supergroup of the late Neoproterozoic Avalonian volcanic arc system of southern Britain, contains a bedding plane with an impoverished assemblage of ivesheadiomorphs that is constrained to between ca. 611 Ma and 569.1 ± 0.9 Ma (total uncertainty). Higher-diversity biotas, including the holotypes of Charnia, Charniodiscus, and Bradgatia, occupy the upper part of the volcaniclastic succession (Maplewell Group) and are dated at 561.9 ± 0.9 Ma (total uncertainty) and younger by zircons interpreted as coeval with eruption and deposition of the Park Breccia, Bradgate Formation. An ashy volcanic-pebble conglomerate in the Hanging Rocks Formation at the very top of the supergroup yielded two U-Pb zircon populations: an older detrital one at ca. 604 Ma, and a younger population at ca. 557 Ma, which is interpreted as the approximate depositional age. The temporal association of the fossiliferous Charnian Supergroup with comparable fossiliferous deep-water successions in Newfoundland, and the probable temporal overlap of the youngest Charnwood macrofossils with those from different paleoenvironmental settings, such as the Ediacaran White Sea macrofossils, indicate a primary role for ecological sensitivity in determining the composition of these late Neoproterozoic communities. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.