New ages for the climactic eruptions at Yellowstone: Single-crystal 40Ar/39Ar dating identifies contamination

Abstract

Research Article| April 01, 1998 New ages for the climactic eruptions at Yellowstone: Single-crystal 40Ar/39Ar dating identifies contamination C. A. Gansecki; C. A. Gansecki 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115 Search for other works by this author on: GSW Google Scholar G. A. Mahood; G. A. Mahood 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115 Search for other works by this author on: GSW Google Scholar M. McWilliams M. McWilliams 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115 Search for other works by this author on: GSW Google Scholar Author and Article Information C. A. Gansecki 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115 G. A. Mahood 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115 M. McWilliams 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1998) 26 (4): 343–346. https://doi.org/10.1130/0091-7613(1998)026<0343:NAFTCE>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation C. A. Gansecki, G. A. Mahood, M. McWilliams; New ages for the climactic eruptions at Yellowstone: Single-crystal 40Ar/39Ar dating identifies contamination. Geology 1998;; 26 (4): 343–346. doi: https://doi.org/10.1130/0091-7613(1998)026<0343:NAFTCE>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 SocietyGeology Search Advanced Search Abstract Ash beds associated with the three climactic Yellowstone ignimbrites form important Quaternary chronostratigraphic markers over much of the continental United States. Previous K-Ar ages determined on crystal concentrates from these ashes varied by as much as 60–100 k.y. Laser-fusion 40Ar/39Ar dating of single sanidine grains from these units reveals a small number of grains with anomalously old ages. Eliminating these from the weighted averages results in highly precise refined ages of 2.003 ± 0.014, 1.293 ± 0.012, and 0.602 ± 0.004 Ma (2σ errors) for the Huckleberry Ridge Tuff, Mesa Falls Tuff, and member B of the Lava Creek Tuff, respectively. Individual single-grain ages that are slightly too old could result from incomplete degassing of xenocrysts in the magma. Electron-microprobe analyses of sanidine splits reveal no obvious xenocrystic compositions, suggesting another possibility—that phenocrysts from the crystallized rind of the magma chamber were re-entrained into the magma prior to eruption. Contamination and natural variation in phenocryst age may create larger uncertainty in bulk-crystal dating of young silicic volcanic rocks than incomplete extraction of Ar from sanidine. 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.