Toward a Neoproterozoic composite carbon-isotope record

Abstract

Research Article| September 01, 2005 Toward a Neoproterozoic composite carbon-isotope record Galen P. Halverson; Galen P. Halverson 1Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138-2902, USA, and Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Building 54-1126, Cambridge, Massachusetts 02139, USA Search for other works by this author on: GSW Google Scholar Paul F. Hoffman; Paul F. Hoffman 2Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138-2902, USA Search for other works by this author on: GSW Google Scholar Daniel P. Schrag; Daniel P. Schrag 2Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138-2902, USA Search for other works by this author on: GSW Google Scholar Adam C. Maloof; Adam C. Maloof 2Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138-2902, USA Search for other works by this author on: GSW Google Scholar A. Hugh N. Rice A. Hugh N. Rice 3Department of Geological Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria Search for other works by this author on: GSW Google Scholar GSA Bulletin (2005) 117 (9-10): 1181–1207. https://doi.org/10.1130/B25630.1 Article history received: 03 May 2004 rev-recd: 17 Jan 2005 accepted: 25 May 2005 first online: 02 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 Galen P. Halverson, Paul F. Hoffman, Daniel P. Schrag, Adam C. Maloof, A. Hugh N. Rice; Toward a Neoproterozoic composite carbon-isotope record. GSA Bulletin 2005;; 117 (9-10): 1181–1207. doi: https://doi.org/10.1130/B25630.1 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 Glacial deposits of Sturtian and Marinoan age occur in the well-studied Neoproterozoic successions of northern Namibia, South Australia, and northwestern Canada. In all three regions, the Marinoan glaciation is presaged by a large negative δ13C anomaly, and the cap carbonates to both glacial units share a suite of unique sedimentological, stratigraphic, and geochemical features. These global chronostratigraphic markers are the bases of a new correlation scheme for the Neoproterozoic that corroborates radiometric data that indicate that there were three glacial epochs between ca. 750 and 580 Ma. Intraregional correlation of Neoproterozoic successions in the present-day North Atlantic region suggests that glacial diamictite pairs in the Polarisbreen Group in northeastern Svalbard and the Tillite Group in eastern Greenland were deposited during the Marinoan glaciation, whereas the younger of a pair of glacials (Mortensnes Formation) in the Vestertana Group of northern Norway was deposited during the third (Gaskiers) Neoproterozoic glaciation. Gaskiers-aged glacial deposits are neither globally distributed nor overlain by a widespread cap carbonate but are associated with an extremely negative δ13C anomaly. The chronology developed here provides the framework for a new, high-resolution model carbon-isotope record for the Neoproterozoic comprising new δ13C (carbonate) data from Svalbard (Akademikerbreen Group) and Namibia (Otavi Group) and data in the literature from Svalbard, Namibia, and Oman. A new U-Pb zircon age of 760 ± 1 Ma from an ash bed in the Ombombo Subgroup in Namibia provides the oldest direct time-calibration point in the compilation, but the time scale of this preliminary δ13C record remains poorly constrained. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.