GLACIAL EROSION RATE FOR THE CORDILLERAN ICE SHEET IN SOUTHEAST ALASKA USING COSMOGENIC 10BE CONCENTRATIONS IN BEDROCK AND PERCHED BOULDERS

2018 ◽  
Author(s):  
Christopher Sbarra ◽  
◽  
Jason P. Briner ◽  
Alia J. Lesnek ◽  
James F. Baichtal
Keyword(s):  
Erosion Rate ◽  
Ice Sheet ◽  
Glacial Erosion ◽  
Southeast Alaska ◽  
Cordilleran Ice Sheet ◽  
Cosmogenic 10Be

scholarly journals Investigating the glacial history of the northern sector of the Cordilleran Ice Sheet with cosmogenic 10Be concentrations in quartz

2010 ◽  
Vol 29 (25-26) ◽  
pp. 3630-3643 ◽  
Author(s):  
Arjen P. Stroeven ◽  
Derek Fabel ◽  
Alexandru T. Codilean ◽  
Johan Kleman ◽  
John J. Clague ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Glacial History ◽  
History Of ◽  
Cordilleran Ice Sheet ◽  
Cosmogenic 10Be ◽  
Northern Sector

A new set of basaltic tephras from Southeast Alaska represent key stratigraphic markers for the late Pleistocene

2019 ◽  
Vol 92 (1) ◽  
pp. 246-256 ◽  
Author(s):  
Paul S. Wilcox ◽  
Jason Addison ◽  
Sarah J. Fowell ◽  
James F. Baichtal ◽  
Ken Severin ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Late Pleistocene ◽  
Ice Sheet ◽  
Volcanic Field ◽  
Southeast Alaska ◽  
Cordilleran Ice Sheet

AbstractThree new tephras have been identified in Southeast Alaska. An 8-cm-thick black basaltic tephra with nine discrete normally graded beds is present in cores from a lake on Baker Island. The estimated age of the tephra is 13,492 ± 237 cal yr BP. Although similar in age to the MEd tephra from the adjacent Mt. Edgecumbe volcanic field, this tephra is geochemically distinct. Black basaltic tephras recovered from two additional sites in Southeast Alaska, Heceta Island and the Gulf of Esquibel, are also geochemically distinct from the MEd tephra. The age of the tephra from Heceta Island is 14,609 ± 343 cal yr BP. Whereas the tephras recovered from Baker Island/Heceta Island/Gulf of Esquibel are geochemically distinct from each other, similarities in the ages of these tephras and the MEd tephra suggest a shared eruptive trigger, possibly crustal unloading caused by retreat of the Cordilleran Ice Sheet. The submerged Addington volcanic field on the continental shelf, which may have been subaerially exposed during the late Pleistocene, is a possible source for the Southeast Alaska tephras.

New constraints on the last deglaciation of the Cordilleran Ice Sheet in coastal Southeast Alaska

2020 ◽  
Vol 96 ◽  
pp. 140-160 ◽  
Author(s):  
Alia J. Lesnek ◽  
Jason P. Briner ◽  
James F. Baichtal ◽  
Alex S. Lyles
Keyword(s):  
Ice Sheet ◽  
Last Deglaciation ◽  
Rapid Phase ◽  
Southeast Alaska ◽  
Alpine Glaciers ◽  
Air Temperatures ◽  
The Last Deglaciation ◽  
Cordilleran Ice Sheet ◽  
Exposure Ages ◽  
Outer Coast

AbstractUnderstanding marine-terminating ice sheet response to past climate transitions provides valuable long-term context for observations of modern ice sheet change. Here, we reconstruct the last deglaciation of marine-terminating Cordilleran Ice Sheet (CIS) margins in Southeast Alaska and explore potential forcings of western CIS retreat. We combine 27 new cosmogenic 10Be exposure ages, 13 recently published 10Be ages, and 25 new 14C ages from raised marine sediments to constrain CIS recession. Retreat from the outer coast was underway by 17 ka, and the inner fjords and sounds were ice-free by 15 ka. After 15 ka, the western margin of the CIS became primarily land-terminating and alpine glaciers disappeared from the outer coast. Isolated alpine glaciers may have persisted in high inland peaks until the early Holocene. Our results suggest that the most rapid phase of CIS retreat along the Pacific coast occurred between ~17 and 15 ka. This retreat was likely driven by processes operating at the ice-ocean interface, including sea level rise and ocean warming. CIS recession after ~15 ka occurred during a time of climatic amelioration in this region, when both ocean and air temperatures increased. These data highlight the sensitivity of marine-terminating CIS regions to deglacial climate change.

scholarly journals Rapid retreat of the southwestern Laurentide Ice Sheet during the Bølling-Allerød interval

Geology ◽  
2021 ◽  
Author(s):  
Sophie Norris ◽  
Lev Tarasov ◽  
Alistair J. Monteath ◽  
John C. Gosse ◽  
Alan J. Hidy ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Human Migration ◽  
The Arctic ◽  
Laurentide Ice Sheet ◽  
Geomorphic Mapping ◽  
Isostatic Adjustment ◽  
Southwestern Margin ◽  
Cordilleran Ice Sheet ◽  
Cosmogenic 10Be ◽  
Exposure Ages

The timing of Laurentide Ice Sheet deglaciation along its southwestern margin controlled the evolution of large glacial lakes and has implications for human migration into the Americas. Accurate reconstruction of the ice sheet’s retreat also constrains glacial isostatic adjustment models and is important for understanding ice-sheet sensitivity to climate forcing. Despite its significance, retreat of the southwestern Laurentide Ice Sheet (SWLIS) is poorly constrained by minimum-limiting 14C data. We present 26 new cosmogenic 10Be exposure ages spanning the western Interior Plains, Canada. Using a Bayesian framework, we combine these data with geomorphic mapping, 10Be, and high-quality minimum-limiting 14C ages to provide an updated chronology. This dataset presents an internally consistent retreat record and indicates that the initial detachment of the SWLIS from its convergence with the Cordilleran Ice Sheet began by ca. 15.0 ka, concurrent with or slightly prior to the onset of the Bølling-Allerød interval (14.7–12.9 ka) and retreated >1200 km to its Younger Dryas (YD) position in ~2500 yr. Ice-sheet stabilization at the Cree Lake Moraine facilitated a meltwater drainage route to the Arctic from glacial Lake Agassiz within the YD, but not necessarily at the beginning. Our record of deglaciation and new YD constraints demonstrate deglaciation of the Interior Plains was ~60% faster than suggested by minimum 14C constraints alone. Numerical modeling of this rapid retreat estimates a loss of ~3.7 m of sea-level equivalent from the SWLIS during the Bølling-Allerød interval.

NORTHERN CORDILLERAN ICE SHEET DISPLAYS A DIACHRONOUS RESPONSE TO MIS 4 FORCING, YUKON TERRITORY,CANADA

2019 ◽  
Author(s):  
Brent C. Ward ◽  
◽  
Jeffrey D. Bond ◽  
Derek Cronmiller ◽  
Derek Turner ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Yukon Territory ◽  
Cordilleran Ice Sheet

Ice-free conditions in southwestern British Columbia at 16000 years BP

1988 ◽  
Vol 25 (6) ◽  
pp. 938-941 ◽  
Author(s):  
John J. Clague ◽  
Ian R. Saunders ◽  
Michael C. Roberts
Keyword(s):  
British Columbia ◽  
Ice Sheet ◽  
Radiocarbon Dates ◽  
Maximum Extent ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

New radiocarbon dates on wood from two exposures in Chilliwack valley, southwestern British Columbia, indicate that this area was ice free and locally forested 16 000 radiocarbon years ago. This suggests that the Late Wisconsinan Cordilleran Ice Sheet reached its maximum extent in this region after 16 000 years BP. The Chilliwack valley dates are the youngest in British Columbia that bear on the growth of the Cordilleran Ice Sheet.

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