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Research Article| September 01, 1969 Potassium-Argon Ages Bearing on the Igneous and Tectonic History of the Elk Mountains and Vicinity, Colorado: A Preliminary Report JOHN D OBRADOVICH; JOHN D OBRADOVICH U.S. Geological Survey, Denver, Colorado Search for other works by this author on: GSW Google Scholar FELIX E MUTSCHLER; FELIX E MUTSCHLER U.S. Geological Survey, Denver, Colorado Search for other works by this author on: GSW Google Scholar BRUCE BRYANT BRUCE BRYANT U.S. Geological Survey, Denver, Colorado Search for other works by this author on: GSW Google Scholar Author and Article Information JOHN D OBRADOVICH U.S. Geological Survey, Denver, Colorado FELIX E MUTSCHLER U.S. Geological Survey, Denver, Colorado BRUCE BRYANT U.S. Geological Survey, Denver, Colorado Publisher: Geological Society of America Received: 11 Feb 1969 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1969, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1969) 80 (9): 1749–1756. https://doi.org/10.1130/0016-7606(1969)80[1749:PABOTI]2.0.CO;2 Article history Received: 11 Feb 1969 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 JOHN D OBRADOVICH, FELIX E MUTSCHLER, BRUCE BRYANT; Potassium-Argon Ages Bearing on the Igneous and Tectonic History of the Elk Mountains and Vicinity, Colorado: A Preliminary Report. GSA Bulletin 1969;; 80 (9): 1749–1756. doi: https://doi.org/10.1130/0016-7606(1969)80[1749:PABOTI]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 SocietyGSA Bulletin Search Advanced Search Abstract K-Ar ages for epizonal plutonic rocks together with field studies indicate that uplift of the Sawatch Range began at least 72 m.y. ago. Vertical uplift of the Sawatch Range was followed or accompanied by gravity sliding of sedimentary rocks along the Elk Range thrust fault. The greatest volume of exposed intrusive rocks in the Elk Mountains, Ruby Range, and West Elk Mountains consists of granodioritic rocks of Oligocene age which are younger than the Elk Range thrust. Miocene and Pliocene(?) mafic dikes were emplaced after most of the structural features in the area had developed. The Treasure Mountain dome near Marble was formed by emplacement of a unique soda granite pluton about 12.5 m.y. ago.Discordant K-Ar and Rb-Sr ages for biotite from the Twin Lakes stock in the Sawatch Range suggest that this large pluton is of Late Cretaceous or early Tertiary age and lost argon during Oligocene plutonism, or is of Eocene age and represents a separate event not yet supported by other radiometric dates from the area. 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.
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