Correlation of quaternary glacial deposits in Alaska

Hamilton, Thomas D.

doi:10.1016/0277-3791(86)90182-4

Cited by 17 publications

(7 citation statements)

References 41 publications

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“…This is especially true for the penultimate glacier advance, which for decades was suspected to post-date the last interglaciation (Hamilton, 1986b(Hamilton, , 1994(Hamilton, , 2001. The penultimate advance culminated between 60 and 50 ka, based on cosmogenic exposure ages of moraine boulders in three valleys from sites up to 800 km apart ( Fig.…”

Section: Discussionmentioning

confidence: 99%

Late Pleistocene mountain glaciation in Alaska: key chronologies

Briner

Kaufman

2008

J Quaternary Science

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Moraine sequences of mountain glaciers can be used to infer spatial and temporal patterns of climate change across the globe. Alaska is an accessible high-latitude location in the Northern Hemisphere and contains a rich record of alpine glaciation. Here, we highlight the key chronologies from three mountain ranges in Alaska that reveal the timing and spatial extent of Late Pleistocene glaciation, and pay particular attention to age of the penultimate glaciation. The most extensive glacier advance of the last glaciation occurred prior to the last global glacial maximum. Cosmogenic exposure ages from moraine boulders in three sites spanning 800 km indicate that this penultimate advance most likely culminated during marine isotope stage (MIS) 4 or early MIS 3. During MIS 2, more limited glacier expansion generated multiple moraines that span from prior to the global Last Glacial Maximum (LGM) through the Lateglacial period. Glaciers retreated from their terminal positions ca. 27-25 ka in arctic Alaska and ca. 22-19 ka in southern Alaska. Moraines in at least two ranges date to 12-11 ka, indicating a glacial advance during the Younger Dryas period. Reconstructed equilibrium-line altitudes of both penultimate and MIS 2 glaciers were lowered only 300-600 mmuch less than elsewhere in the Americas. Alaska is documented to have been more arid during MIS 2, perhaps due in large part to the exposure of the Bering-Chukchi platform during eustatic sea-level lowering. The restricted ice extent is also consistent with the output of climate models that simulate a lack of significant summer cooling.

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Section: Discussionmentioning

confidence: 99%

Late Pleistocene mountain glaciation in Alaska: key chronologies

Briner

Kaufman

2008

J Quaternary Science

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“…The glacial history of Alaska has been recently reviewed by Kaufman and Manley (2004), which built upon past reviews (e.g., Péwé et al, 1965;Péwé, 1975;Hamilton, 1986aHamilton, , 1994. While Alaska was extensively glaciated during late Pleistocene ice advances, large portions of the state escaped glacial cover (cf.…”

Section: Late Pleistocene Glacial History Of Alaska: Previous Work Nmentioning

confidence: 99%

“…The strikingly limited extent of late Wisconsin glaciers in Alaska relative to previous advances has long been recognized (Péwé et al, 1965;Hopkins, 1982;Hamilton et al, 1986a;Kaufman and Manley, 2004). Most mountain ranges preserve clear morainal evidence for the extent of pre-late Wisconsin (penultimate) glaciers.…”

Section: Introductionmentioning

confidence: 99%

Cosmogenic exposure dating of late Pleistocene moraine stabilization in Alaska

Briner

Kaufman

Manley

et al. 2005

Geol Soc America Bull

181

163

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Seventy-three new 10 Be/ 26 Al 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 diffi cult 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 14 C 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.

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“…Time-distance diagram illustrating the extent and chronology (in 14 C kyr) of late Quaternary glacier advances in three areas of Alaska, based on Porter et al (1983) with data also from Hamilton (1986) and Mann and Peteet (1994). and until ca.…”

Section: Figurementioning

confidence: 99%

“…Interpretation and speculation from data for Kodiak Island and the Alaska Peninsula from Mann & Peteet (1994) B. Glacier advances and outwash in the Central Brooks Range and Koyukuk Lowlands, from Porter et al, (1983) and Hamilton (1986).…”

mentioning

confidence: 99%

Interhemispheric synchroneity of Marine Oxygen Isotope Stage 2 glacier fluctuations along the American cordilleras transect

Clapperton

2000

J. Quaternary Sci.

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Correlation of quaternary glacial deposits in Alaska

Cited by 17 publications

References 41 publications

Late Pleistocene mountain glaciation in Alaska: key chronologies

Late Pleistocene mountain glaciation in Alaska: key chronologies

Cosmogenic exposure dating of late Pleistocene moraine stabilization in Alaska

Interhemispheric synchroneity of Marine Oxygen Isotope Stage 2 glacier fluctuations along the American cordilleras transect

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