Cosmogenic exposure dating of late Pleistocene moraine stabilization in Alaska

Abstract

Research Article| July 01, 2005 Cosmogenic exposure dating of late Pleistocene moraine stabilization in Alaska Jason P. Briner; Jason P. Briner 1Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80309-0450, USA Search for other works by this author on: GSW Google Scholar Darrell S. Kaufman; Darrell S. Kaufman 2Department of Geology and Department of Environmental Sciences, Northern Arizona University, Flagstaff, Arizona 86011, USA Search for other works by this author on: GSW Google Scholar William F. Manley; William F. Manley 3Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80309-0450, USA Search for other works by this author on: GSW Google Scholar Robert C. Finkel; Robert C. Finkel 4Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, California 94550, USA Search for other works by this author on: GSW Google Scholar Marc W. Caffee Marc W. Caffee 5Purdue Rare Isotope Measurement Laboratory and Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Jason P. Briner 1Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80309-0450, USA Darrell S. Kaufman 2Department of Geology and Department of Environmental Sciences, Northern Arizona University, Flagstaff, Arizona 86011, USA William F. Manley 3Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80309-0450, USA Robert C. Finkel 4Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, California 94550, USA Marc W. Caffee 5Purdue Rare Isotope Measurement Laboratory and Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA Publisher: Geological Society of America Received: 27 May 2004 Revision Received: 08 Dec 2004 Accepted: 29 Dec 2004 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2005) 117 (7-8): 1108–1120. https://doi.org/10.1130/B25649.1 Article history Received: 27 May 2004 Revision Received: 08 Dec 2004 Accepted: 29 Dec 2004 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Jason P. Briner, Darrell S. Kaufman, William F. Manley, Robert C. Finkel, Marc W. Caffee; Cosmogenic exposure dating of late Pleistocene moraine stabilization in Alaska. GSA Bulletin 2005;; 117 (7-8): 1108–1120. doi: https://doi.org/10.1130/B25649.1 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 Seventy-three new 10Be/26Al ages from 57 moraine boulders and 2 tors, together with 43 previously published cosmogenic exposure ages from 41 moraine boulders, allow us to critique the use of cosmogenic exposure (CE) dating of moraine boulders in Alaska. Boulder exhumation during moraine degradation likely gives rise to the largest uncertainty in constraining the timing of initial moraine stabilization following ice retreat. Isotopic inheritance appears to be most important for moraines deposited close to their cirque headwalls. Boulder-surface (bedrock) erosion rate can be roughly constrained and leads to a range in moraine stabilization ages. Snow-cover history is difficult to constrain, but its effect is thought to be minor for the tall boulders sampled.Despite these complications, the CE ages provide important new information regarding the timing of the last and penultimate glaciations in Alaska. Three penultimate moraines yielded CE ages that overlap with marine isotope stage (MIS) 4/early MIS 3 (45–65 ka) rather than MIS 6 (ca. 140 ka). Based on a combination of our new CE chronologies and existing 14C ages from six study areas, glaciers retreated from their local late Wisconsin maxima: ca. 24–27 ka, Kokrines Hills (west-interior Alaska); ca. 24–26 ka, northeastern Brooks Range (NE Alaska); ca. 21–23 ka, Yukon Tanana Upland (east-interior Alaska); ca. 22 ka, Ahklun Mountains (SW Alaska); ca. 20 ka, western Alaska Range (central Alaska); ca. 16–18 ka, Chuilnuk Mountains (SW Alaska). Overall, glacier retreat was concurrent with the peak of the last global glacial maximum, probably in response to limited moisture availability. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.