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Carbon isotope stratigraphy of Upper Cambrian (Steptoean Stage) sequences of the eastern Great Basin: Record of a global oceanographic event

1998; Geological Society of America; Volume: 110; Issue: 3 Linguagem: Inglês

10.1130/0016-7606(1998)110 2.3.co;2

1943-2674

Matthew R. Saltzman, Bruce Runnegar, Kyger C. Lohmann,

Geological and Geochemical Analysis

Research Article| March 01, 1998 Carbon isotope stratigraphy of Upper Cambrian (Steptoean Stage) sequences of the eastern Great Basin: Record of a global oceanographic event Matthew R. Saltzman; Matthew R. Saltzman 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90095 Search for other works by this author on: GSW Google Scholar Bruce Runnegar; Bruce Runnegar 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90095 Search for other works by this author on: GSW Google Scholar Kyger C. Lohmann Kyger C. Lohmann 2Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48104 Search for other works by this author on: GSW Google Scholar Author and Article Information Matthew R. Saltzman 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90095 Bruce Runnegar 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90095 Kyger C. Lohmann 2Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48104 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1998) 110 (3): 285–297. https://doi.org/10.1130/0016-7606(1998)110 2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Matthew R. Saltzman, Bruce Runnegar, Kyger C. Lohmann; Carbon isotope stratigraphy of Upper Cambrian (Steptoean Stage) sequences of the eastern Great Basin: Record of a global oceanographic event. GSA Bulletin 1998;; 110 (3): 285–297. doi: https://doi.org/10.1130/0016-7606(1998)110 2.3.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 SocietyGSA Bulletin Search Advanced Search Abstract A large, global positive excursion in δ13C (from ∼0.5 to 4.5‰) during the Late Cambrian Pterocephaliid biomere/Steptoean Stage (Aphelaspis-Elvinia zones) is documented at high stratigraphic resolution in three sections in the eastern Great Basin. The excursion, which we refer to as the Steptoean Positive Carbon Isotope Excursion, or SPICE excursion, began coincident with a world-wide extinction event. The δ13C data from the Great Basin reflect global seawater values in a wide range of lithologies, including oolitic grainstones, wackestones, thrombolitic boundstones, and flat-pebble conglomerates. We use a section at Shingle Pass in the southern Egan Range to divide the Pterocephaliid biomere into eight isotope steps that represent equal divisions of the δ13C rise and fall (±4‰). This provides a basis for recognition of a revised chronostratigraphic framework for the Pterocephaliid biomere/Steptoean Stage.Strata deposited during the beginning of the SPICE excursion record a major change in the pattern of sedimentation in the eastern Great Basin. This is reflected in a siliciclastic-carbonate transition at Shingle Pass, Nevada, and a carbonate-siliciclastic transition at the House Range and Lawson Cove sections in Utah. A regional siliciclastic influx recognized throughout the Great Basin occurs near the peak of the SPICE excursion. Carbon isotope analyses from cratonal sections in Wyoming provide independent evidence that a major sedimentary hiatus took place on the craton during the time of the SPICE excursion.The correlated changes in δ13C, relative sea level, and the marine biota during the SPICE excursion provide remarkably detailed records of a major paleoceanographic event. We speculate that changes in sea level, climate, or tectonics may have triggered the SPICE excursion and coeval extinction event. Subsequent burial of organic carbon caused the increase in δ13C and may have led to an interval of global cooling. The results of this study lend confidence to carbon-isotopic studies of pre-Mesozoic rocks. 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.