Terminal Ordovician extinction: Geochemical analysis of the Ordovician/Silurian boundary, Anticosti Island, Quebec

Abstract

Research Article| May 01, 1986 Terminal Ordovician extinction: Geochemical analysis of the Ordovician/Silurian boundary, Anticosti Island, Quebec C. J. Orth; C. J. Orth 1Isotope and Nuclear Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Search for other works by this author on: GSW Google Scholar J. S. Gilmore; J. S. Gilmore 1Isotope and Nuclear Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Search for other works by this author on: GSW Google Scholar L R. Quintana; L R. Quintana 1Isotope and Nuclear Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Search for other works by this author on: GSW Google Scholar P. M. Sheehan P. M. Sheehan 2Department of Geology, Milwaukee Public Museum, Milwaukee, Wisconsin 53233 Search for other works by this author on: GSW Google Scholar Author and Article Information C. J. Orth 1Isotope and Nuclear Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 J. S. Gilmore 1Isotope and Nuclear Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 L R. Quintana 1Isotope and Nuclear Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 P. M. Sheehan 2Department of Geology, Milwaukee Public Museum, Milwaukee, Wisconsin 53233 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1986) 14 (5): 433–436. https://doi.org/10.1130/0091-7613(1986)14<433:TOEGAO>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation C. J. Orth, J. S. Gilmore, L R. Quintana, P. M. Sheehan; Terminal Ordovician extinction: Geochemical analysis of the Ordovician/Silurian boundary, Anticosti Island, Quebec. Geology 1986;; 14 (5): 433–436. doi: https://doi.org/10.1130/0091-7613(1986)14<433:TOEGAO>2.0.CO;2 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 Elemental abundances (including Ir), carbon and oxygen ratios in carbonates, mineral content, and thin sections have been measured in samples collected across the conodont-defined Ordovician/Silurian (O/S) boundary exposed on Anticosti Island, Quebec. The Ir concentrations ranged from 5 to a maximum at the boundary of 58 parts per trillion (ppt). However, there is no evidence, on the basis of these Ir results, for the association of a large-body-Earth impact with the O/S extinction, because the Ir concentrations, like those of most other trace elements, are simply proportional to the clay (Al) content in the carbonate sequence. The 13C/12C and 18O/16O ratios decrease abruptly at the boundary, then just as abruptly increase to a long period of higher than preboundary ratios. These patterns are probably related to the salinity in the seaway, which was shallowing up to boundary time and then deepened and developed patch-reefs. Fresh-water input from rivers would have been most influential during the shallow-water conditions. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.