The Denali fault system and Alaska Range of Alaska: Evidence for underplated Mesozoic flysch from magnetotelluric surveys

Abstract

Research Article| February 01, 1990 The Denali fault system and Alaska Range of Alaska: Evidence for underplated Mesozoic flysch from magnetotelluric surveys WILLIAM D. STANLEY; WILLIAM D. STANLEY 1U.S. Geological Survey, Box 25046, M.S. 964, Denver Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar VICTOR F. LABSON; VICTOR F. LABSON 1U.S. Geological Survey, Box 25046, M.S. 964, Denver Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar WARREN J. NOKLEBERG; WARREN J. NOKLEBERG 2US. Geological Survey, 345 Middlefield Road Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar BELA CSEJTEY, JR.; BELA CSEJTEY, JR. 2US. Geological Survey, 345 Middlefield Road Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar MICHAEL A. FISHER MICHAEL A. FISHER 2US. Geological Survey, 345 Middlefield Road Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Author and Article Information WILLIAM D. STANLEY 1U.S. Geological Survey, Box 25046, M.S. 964, Denver Federal Center, Denver, Colorado 80225 VICTOR F. LABSON 1U.S. Geological Survey, Box 25046, M.S. 964, Denver Federal Center, Denver, Colorado 80225 WARREN J. NOKLEBERG 2US. Geological Survey, 345 Middlefield Road Menlo Park, California 94025 BELA CSEJTEY, JR. 2US. Geological Survey, 345 Middlefield Road Menlo Park, California 94025 MICHAEL A. FISHER 2US. Geological Survey, 345 Middlefield Road Menlo Park, California 94025 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1990) 102 (2): 160–173. https://doi.org/10.1130/0016-7606(1990)102<0160:TDFSAA>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 Email Permissions Search Site Citation WILLIAM D. STANLEY, VICTOR F. LABSON, WARREN J. NOKLEBERG, BELA CSEJTEY, MICHAEL A. FISHER; The Denali fault system and Alaska Range of Alaska: Evidence for underplated Mesozoic flysch from magnetotelluric surveys. GSA Bulletin 1990;; 102 (2): 160–173. doi: https://doi.org/10.1130/0016-7606(1990)102<0160:TDFSAA>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 Regional magnetotelluric surveys recently completed across the central and eastern Alaska Range of Alaska provide evidence for large volumes of conductive rocks beneath the core of the range. These conductive rocks may represent a formerly extensive, but now collapsed, Mesozoic flysch basin formed on the leading edge of the Talkeetna superterrane (amalgamated Wrangellia, Peninsular, and Alexander terranes). The docking of the Talkeetna superterrane caused large-scale oblique thrusting, folding, and metamorphism in the flysch basin, and formation of a megasuture along which the Cenozoic strike-slip Denali fault system developed. The deep magnetotelluric soundings and seismic reflection data suggest the possibility that the highly conductive rocks were tectonically emplaced beneath the thin crystalline sheet constituting the southern Yukon-Tanana terrane over a broad region of the Alaska Range. The conductive rocks are locally correlated with surface outcrops of Mesozoic black shales that are part of Upper Jurassic and Cretaceous flysch but may be composed of Paleozoic carbonaceous shales as well. In either case, their extremely low resistivities make them a valuable marker horizon for tectonic studies. The conductive rocks are interpreted to extend to depths of greater than 20 km and were mapped north and northeast of the Denali fault for more than 50 km. The magnetotelluric surveys represent the first large-scale surveys done in Alaska, but the structures mapped are similar to those observed in large, compressed flysch basins in the eastern Alps and Carpathian Mountains of Europe. The results of these surveys bear on several key tectonic questions, including development of the ancestral Denali fault, and collapse and possible underplating of an extensive Mesozoic flysch system and associated igneous arc. 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.