Sub-million-year age resolution of Precambrian igneous events by thermal extraction–thermal ionization mass spectrometer Pb dating of zircon: Application to crystallization of the Sudbury impact melt sheet

Research Article| May 01, 2008 Sub-million-year age resolution of Precambrian igneous events by thermal extraction–thermal ionization mass spectrometer Pb dating of zircon: Application to crystallization of the Sudbury impact melt sheet Donald W. Davis Donald W. Davis 1Jack Satterly Geochronology Laboratory, Department of Geology, University of Toronto, 22 Russell Street, Toronto, Ontario M5S 3B1, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Donald W. Davis 1Jack Satterly Geochronology Laboratory, Department of Geology, University of Toronto, 22 Russell Street, Toronto, Ontario M5S 3B1, Canada Publisher: Geological Society of America Received: 12 Oct 2007 Revision Received: 21 Jan 2008 Accepted: 23 Jan 2008 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2008 Geological Society of America Geology (2008) 36 (5): 383–386. https://doi.org/10.1130/G24502A.1 Article history Received: 12 Oct 2007 Revision Received: 21 Jan 2008 Accepted: 23 Jan 2008 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Donald W. Davis; Sub-million-year age resolution of Precambrian igneous events by thermal extraction–thermal ionization mass spectrometer Pb dating of zircon: Application to crystallization of the Sudbury impact melt sheet. Geology 2008;; 36 (5): 383–386. doi: https://doi.org/10.1130/G24502A.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 A new approach to zircon dating is described that potentially offers a considerable improvement in the accuracy of 207Pb/206Pb ages on a wider variety of samples and at less cost than that generally available from conventional techniques. Zircon is first preheated in a vacuum to evaporate Pb from altered domains, leaving predominantly Pb with isotopes that preserve the primary age of the sample. Refractory Pb is removed from the zircon by thermal extraction at higher temperature directly into a silica-melt ionization activator within a thermal ionization mass spectrometer. This produces strong ion beams that allow 207Pb/206Pb isotope ratios to be measured to high precision (±10−4) with almost negligible contamination from common Pb. Isotope fractionation appears to be more reproducible than with conventional solution analysis, allowing routine age determinations with precision of ~±0.2 m.y. for the Precambrian. As a test application, zircon from a noritic boundary phase of the Sudbury impact melt gives 1849.53 ± 0.21 Ma, while a phase from several hundred meters higher in the noritic layer is resolvably younger at 1849.11 ± 0.19 Ma (95% confidence errors). The enhanced precision and ease of application of this method should greatly increase the scientific power and availability of zircon dating. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.