Abstract This article describes the regional effects of Cenozoic subduction along the outboard margin of the Northern Cordillera (Alaska, USA, and Western Canada), and thereby acquaints the reader with several chapters of the e-book Dynamic Geology of the Northern Cordillera (Alaska, Western Canada, and Adjacent Marine Areas). This article and the e-book are written for earth-science students and teachers. The level of writing for the article and the source e-book is that of popular science magazines, and readers are encouraged to share this article with students and laypersons. The main thrust of the article is to present and describe a suite of ten regional topographic, bathymetric, and geologic maps, and two figures portraying deep-crustal sections that illustrate the regional effects of Cenozoic subduction along the outboard margin of the North American Cordillera. The regional maps and cross sections are described in a way that a teacher might describe a map to students. Cenozoic subduction along the margin of the Northern Cordillera resulted in the formation of the following: (1) underthrusting of terranes and oceanic lithosphere beneath Southern Alaska; (2) landscapes, including narrow continental shelves along Southern and Southeastern Alaska and Western Canada (the Canadian Cordillera) and continental-margin mountain ranges, including the Alaska Peninsula, Chugach Range, Saint Elias Mountains, and Cascade Mountains; (3) sedimentary basins; (4) an array of active continental strike-slip and thrust faults (inboard of subduction zones); (5) earthquake belts related to subduction of terranes and oceanic plates; (6) active volcanoes, including continental-margin arcs (the Aleutian, Wrangell, and Cascade Arcs) linked to subduction zones, and interior volcanic belts related to strike-slip faulting or to hot spots; (7) lode and placer mineral deposits related to continental margin arcs or subduction of oceanic ridges; (8) hot springs related to continental-margin arcs; (9) plate movements as recorded from GPS measurements; and (10) underthrusting of terranes and oceanic lithosphere beneath the Northern Cordillera.
Research Article| January 01, 1990 Paleoclimatic forcing of magnetic susceptibility variations in Alaskan loess during the late Quaternary James E. Begét; James E. Begét 1Department of Geology and Geophysics, University of Alaska, Fairbanks, Alaska 99775-0760 Search for other works by this author on: GSW Google Scholar David B. Stone; David B. Stone 1Department of Geology and Geophysics, University of Alaska, Fairbanks, Alaska 99775-0760 Search for other works by this author on: GSW Google Scholar Daniel B. Hawkins Daniel B. Hawkins 1Department of Geology and Geophysics, University of Alaska, Fairbanks, Alaska 99775-0760 Search for other works by this author on: GSW Google Scholar Author and Article Information James E. Begét 1Department of Geology and Geophysics, University of Alaska, Fairbanks, Alaska 99775-0760 David B. Stone 1Department of Geology and Geophysics, University of Alaska, Fairbanks, Alaska 99775-0760 Daniel B. Hawkins 1Department of Geology and Geophysics, University of Alaska, Fairbanks, Alaska 99775-0760 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1990) 18 (1): 40–43. https://doi.org/10.1130/0091-7613(1990)018<0040:PFOMSV>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 James E. Begét, David B. Stone, Daniel B. Hawkins; Paleoclimatic forcing of magnetic susceptibility variations in Alaskan loess during the late Quaternary. Geology 1990;; 18 (1): 40–43. doi: https://doi.org/10.1130/0091-7613(1990)018<0040:PFOMSV>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 Visual matches and statistical tests suggest correlations between marine isotope curves, retrodictive solar insolation at lat 65°N, and magnetic susceptibility profiles through late Quaternary age Alaskan loess sections. The susceptibility changes largely appear to reflect variability in magnetite content due to climatically controlled changes in wind intensity and competence. Magnetic susceptibility profiles through massive loess can provide stratigraphic context for intercalated paleosols and tephras. A prominent paleosol correlated with marine isotope stage 5 occurs several metres above the Old Crow ash in loess sections, indicating that this important tephra is older than suggested by thermoluminescence dates, and may have been deposited ca. 215 ±25 ka. 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.
Paleomagnetic determinations of the inclination of the ancient geomagnetic field for localities in the Alaska Peninsula, Wrangellia, Chugach and Kuskokwim tectonostratigraphic terranes of Alaska show systematic northward motion from late Cretaceous time until the present. Prior to this, the ambiguity of polarity of the ancient geomagnetic field allow several interpretations; however, the preferred interpretation involves southerly motion of the terranes from Triassic to Early Jurrassic time, and steady northward motion from then up to the present. The latitudinal rate is about 6 cm/yr.
Research Article| May 01, 1991 EDGE deep seismic reflection transect of the eastern Aleutian arc-trench layered lower crust reveals underplating and continental growth J. Casey Moore; J. Casey Moore 1Department of Earth Sciences, University of California, Santa Cruz, California 95064 Search for other works by this author on: GSW Google Scholar John Diebold; John Diebold 2Lamont Doherty Geological Observatory, Columbia University, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar M. A. Fisher; M. A. Fisher 3U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar J. Sample; J. Sample 4Department of Earth and Space Sciences, University of California, Los Angeles, California 90024 Search for other works by this author on: GSW Google Scholar T. Brocher; T. Brocher 3U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar M. Talwani; M. Talwani 5Houston Area Research Center, 4802 Research Forest Drive, The Woodlands, Texas 77381 Search for other works by this author on: GSW Google Scholar John Ewing; John Ewing 5Houston Area Research Center, 4802 Research Forest Drive, The Woodlands, Texas 77381 Search for other works by this author on: GSW Google Scholar R. von Huene; R. von Huene 6Geomar, Wischhofstrasse 1-4,2300 Kiel 14, Germany Search for other works by this author on: GSW Google Scholar C. Rowe; C. Rowe 7Geophysical Institute, University of Alaska, Fairbanks, Alaska 99701 Search for other works by this author on: GSW Google Scholar D. Stone; D. Stone 7Geophysical Institute, University of Alaska, Fairbanks, Alaska 99701 Search for other works by this author on: GSW Google Scholar Chris Stevens; Chris Stevens 3U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Dale Sawyer Dale Sawyer 8Department of Geology, Rice University, Houston, Texas 77005 Search for other works by this author on: GSW Google Scholar Geology (1991) 19 (5): 420–424. https://doi.org/10.1130/0091-7613(1991)019<0420:EDSRTO>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 MailTo Tools Icon Tools Get Permissions Search Site Citation J. Casey Moore, John Diebold, M. A. Fisher, J. Sample, T. Brocher, M. Talwani, John Ewing, R. von Huene, C. Rowe, D. Stone, Chris Stevens, Dale Sawyer; EDGE deep seismic reflection transect of the eastern Aleutian arc-trench layered lower crust reveals underplating and continental growth. Geology 1991;; 19 (5): 420–424. doi: https://doi.org/10.1130/0091-7613(1991)019<0420:EDSRTO>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 An EDGE deep crustal seismic reflection transect of the eastern Aleutian arc-trench traces oceanic crust and Moho more than 200 km beneath the accretionary prism to depths of more than 30 km. These horizons project beneath a prominent sequence of layered reflectors that extends from about 9 to 35 km beneath the Mesozoic core of the prism. Earthquake hypocenters imply continuity of the downgoing lithosphere from the base of the layered reflectors to beneath and beyond the active Augustine volcano. Rapid lateral growth of the prism in Eocene-Oligocene time coincided with uplift of the Mesozoic core of the prism. During lateral growth, maintenance of critical taper requires thickening, either by internal deformation or underplating. Because exposed rocks show only modest postemplacement shortening, thickening most likely occurred by underplating, probably of the layered reflectors. The overall geometry of the layered reflectors is reminiscent of nappe structures, and their emplacement may represent crustal-scale duplexing associated with underplating. The EDGE reflection data and borehole results indicate that the shelf edge is marked by an active out-of-sequence thrust that separates the Paleogene and Neogene prisms. This thrust apparently developed in response to the prism's need to maintain critical taper and demonstrates that contrasts in lithology can result from mechanisms other than terrane emplacement. 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.
