Radiometric Ages and Stratigraphic Sequence of Volcanic and Plutonic Rocks, Southern Nye and Western Lincoln Counties, Nevada

Abstract

Research Article| September 01, 1970 Radiometric Ages and Stratigraphic Sequence of Volcanic and Plutonic Rocks, Southern Nye and Western Lincoln Counties, Nevada RICHARD F MARVIN; RICHARD F MARVIN U.S. Geological Survey, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar F. M BYERS, JR.; F. M BYERS, JR. U.S. Geological Survey, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar HARALD H MEHNERT; HARALD H MEHNERT U.S. Geological Survey, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar PAUL P ORKILD; PAUL P ORKILD U.S. Geological Survey, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar T. W STERN T. W STERN U.S. Geological Survey, Washington, D.C. 20242 Search for other works by this author on: GSW Google Scholar Author and Article Information RICHARD F MARVIN U.S. Geological Survey, Denver, Colorado 80225 F. M BYERS, JR. U.S. Geological Survey, Denver, Colorado 80225 HARALD H MEHNERT U.S. Geological Survey, Denver, Colorado 80225 PAUL P ORKILD U.S. Geological Survey, Denver, Colorado 80225 T. W STERN U.S. Geological Survey, Washington, D.C. 20242 Publisher: Geological Society of America Received: 25 Aug 1969 Revision Received: 09 Mar 1970 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1970, 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 (1970) 81 (9): 2657–2676. https://doi.org/10.1130/0016-7606(1970)81[2657:RAASSO]2.0.CO;2 Article history Received: 25 Aug 1969 Revision Received: 09 Mar 1970 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation RICHARD F MARVIN, F. M BYERS, HARALD H MEHNERT, PAUL P ORKILD, T. W STERN; Radiometric Ages and Stratigraphic Sequence of Volcanic and Plutonic Rocks, Southern Nye and Western Lincoln Counties, Nevada. GSA Bulletin 1970;; 81 (9): 2657–2676. doi: https://doi.org/10.1130/0016-7606(1970)81[2657:RAASSO]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 The geochronology of Tertiary igneous events at the Nevada Test Site and adjacent area is outlined by 36 recently determined K-Ar ages, together with other published K-Ar ages. The first evidence of Tertiary igneous activity is the ash-fall bedded tuffs in the Horse Spring Formation. One such tuff has been dated as 29 m.y. old (late Oligocene). Other ash-flow tuffs and lavas formed during the Miocene and Pliocene, according to radiometric age determinations. The youngest ash-flow tuff in this area is about 6 m.y. old.Great volumes of ash and lava were spewed forth 13 to 11 m.y. ago to form the Paintbrush and Timber Mountain Tuffs. Sixteen replicate age determinations on minerals from four densely welded ash-flow tuffs from these formations gave a pooled standard deviation of about ± 2 percent error, provided anomalous ages were rejected on the basis of rock alteration or analytical difficulties.In the Air Force Gunnery Range, just north of the test site, K-Ar ages suggest that the oldest ash flows, the Monotony Tuff, were emplaced 27.6 m.y. ago (late Oligocene) and were followed by outpourings of lava and ash throughout most of the Miocene. Youngest dated lava is about 13 m.y. old.In the southern Egan and northern Seaman Ranges of central Nevada, the Needles Range (?) Formation has an averaged K-Ar age of about 30 m.y., which compares closely with 29.2 m.y., the average of four earlier K-Ar ages determined by other investigators on known Needles Range Formation in eastern Nevada and western Utah.K-Ar ages given by micas from two exposed plutons in the Nevada Test Site suggest emplacement of these plutons at about 93 m.y. ago (early Late Cretaceous), although earlier emplacement in the Mesozoic would be more consistent with Pb-α ages. 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.