Isotopic Ages of Igneous and Metamorphic Boulders from the Haymond Formation (Pennsylvanian), Marathon Basin, Texas, and their Significance

Research Article| February 01, 1969 Isotopic Ages of Igneous and Metamorphic Boulders from the Haymond Formation (Pennsylvanian), Marathon Basin, Texas, and their Significance RODGER E DENISON; RODGER E DENISON Mobil Research and Development Corporation, Field Research Laboratory, Dallas, Texas Search for other works by this author on: GSW Google Scholar GEORGE S KENNY; GEORGE S KENNY Mobil Research and Development Corporation, Field Research Laboratory, Dallas, Texas Search for other works by this author on: GSW Google Scholar WILLIAM H BURKE, JR.; WILLIAM H BURKE, JR. Mobil Research and Development Corporation, Field Research Laboratory, Dallas, Texas Search for other works by this author on: GSW Google Scholar ERNEST A HETHERINGTON, JR. ERNEST A HETHERINGTON, JR. Mobil Research and Development Corporation, Field Research Laboratory, Dallas, Texas Search for other works by this author on: GSW Google Scholar Author and Article Information RODGER E DENISON Mobil Research and Development Corporation, Field Research Laboratory, Dallas, Texas GEORGE S KENNY Mobil Research and Development Corporation, Field Research Laboratory, Dallas, Texas WILLIAM H BURKE, JR. Mobil Research and Development Corporation, Field Research Laboratory, Dallas, Texas ERNEST A HETHERINGTON, JR. Mobil Research and Development Corporation, Field Research Laboratory, Dallas, Texas Publisher: Geological Society of America Received: 02 Aug 1968 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 (2): 245–256. https://doi.org/10.1130/0016-7606(1969)80[245:IAOIAM]2.0.CO;2 Article history Received: 02 Aug 1968 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation RODGER E DENISON, GEORGE S KENNY, WILLIAM H BURKE, ERNEST A HETHERINGTON; Isotopic Ages of Igneous and Metamorphic Boulders from the Haymond Formation (Pennsylvanian), Marathon Basin, Texas, and their Significance. GSA Bulletin 1969;; 80 (2): 245–256. doi: https://doi.org/10.1130/0016-7606(1969)80[245:IAOIAM]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 Twelve whole-rock and mica ages have been determined on igneous and metamorphic boulders from the Haymond Formation in the Marathon Basin. Ages range from 370 to 410 m.y., indicating that these rocks were formed during the period from Middle Devonian to Late Silurian. The granitic gneisses and metarhyolitic rocks have distinctive petrographic and chemical characteristics which suggest that the rocks were derived from the partial melting of clastic sediments. This is supported by the relatively high initial Sr 87/86 ratio of 0.713. The petrographic and isotopic evidence supports the following conclusions: (1) a geosyncline to the southeast of the Marathon depositional basin probably reached maximum subsidence in Silurian-Devonian time. (2) the partial melting in the downwarped geosyncline and resulting volcanism offers a source for the silica in the Caballos Novaculite, (3) the igneous and metamorphic activity in the geosyncline was followed closely by mountain building which supplied the source for the flysch sequence in the Marathon depositional basin. The mountains formed during this interval are named the Llanoria Mountains, and the orogeny causing the uplift is called the Llanorian Orogeny. Ten samples were dated from Texas and Mexico in an unsuccessful search for the specific source area for the boulders. 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.