Quaternary glacial, lacustrine, and fluvial interactions in the western Noatak basin, Northwest Alaska

Hamilton, Thomas D.

doi:10.1016/s0277-3791(00)00110-4

Cited by 37 publications

(71 citation statements)

References 12 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%

“…In the Noatak basin of the western Brooks Range, two separate advances are younger than the 140 ka Old Crow tephra and older than 36-34 ka (Hamilton, 2001). There are no published luminescence or cosmogenic exposure ages on Itkillik I (penultimate) drift in the Brooks Range.…”

Section: Brooks Rangementioning

confidence: 99%

“…2) is bracketed in both the central (Hamilton, 1982) and western Brooks Range (Hamilton, 2001) between 30 and 13 ka. Numerous 14 C ages have been reported from Itkillik II outwash in the Koyakuk River area on the south side of the range (Hamilton, 1982).…”

Section: Brooks Rangementioning

confidence: 99%

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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%

Section: Brooks Rangementioning

confidence: 99%

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Late Pleistocene mountain glaciation in Alaska: key chronologies

Briner

Kaufman

2008

J Quaternary Science

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“…Holocene and Pleistocene alluvial fills and terraces along streams on the North Slope have not been studied in detail, though scattered 14 C dates indicate that many formed between 14,000 and 8000 14 C yr BP (Nelson and Carter, 1987;Dinter et al, 1990). The Pleistocene glaciation of the Brooks Range created a complex succession of glacierdammed lakes with associated fluvial terraces and shorelines in the upper Noatak valley (Hamilton, 2001). Glaciation was accompanied by alluvial and aeolian activity in the Kobuk valley south of the range .…”

Section: Paleohydrologymentioning

confidence: 99%

“…Net downcutting began after 8700 14 C yr BP that has continued to the present. These changes occurred in catchments regardless of whether their headwaters were in the Brooks Range or in the Arctic Foothills, eliminating the possibility that glaciers controlled their dynamics (cf., Ashley and Hamilton, 1993;Hamilton, 2001). The fact that the Ikpikpuk River was downcutting during the YD, a time when the Ikpikpuk Dunes were active on the Arctic Coastal Plain (Carter, 1993), indicates that changes in base level caused by dune movements downstream (cf., Loope et al, 1995) did not affect fluvial dynamics at the study sections.…”

Section: Fluvial Historymentioning

confidence: 99%

Responses of an arctic landscape to Lateglacial and early Holocene climatic changes: the importance of moisture

Mann

Peteet

Reanier³

et al. 2002

Quaternary Science Reviews

117

132

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Many of the physical and biological processes that characterize arctic ecosystems are unique to high latitudes, and their sensitivities to climate change are poorly understood. Stratigraphic records of land-surface processes and vegetation change in the Arctic Foothills of northern Alaska reveal how tundra landscapes responded to climatic changes between 13,000 and 8000 14 C yr BP. Peat deposition began and shrub vegetation became widespread ca. 12,500 14 C yr BP, probably in response to the advent of warmer and wetter climate. Increased slope erosion caused rapid alluviation in valleys, and Populus trees spread northward along braided floodplains before 11,000 14 C yr BP. Lake levels fell and streams incised their floodplains during the Younger Dryas (YD) (11,000-10,000 14 C yr BP). A hiatus in records of Populus suggest that its geographic range contracted, and pollen records of other species suggest a cooler and drier climate during this interval. Basal peats dating to the YD are rare, suggesting that rates of paludification slowed. Immediately after 10,000 14 C yr BP, lake levels rose, streams aggraded rapidly again, intense solifluction occurred, and Populus re-invaded the area. Moist acidic tundra vegetation was widespread by 8500 14 C yr BP along with wet, organic-rich soils. Most of these landscape-scale effects of climatic change involved changes in moisture. Although low temperature is the most conspicuous feature of arctic climate, shifts in effective moisture may be the proximate cause for many of the impacts that climate change has in arctic regions. r

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Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change

Gaglioti

Mann

Jones

et al. 2014

J. Geophys. Res. Biogeosci.

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Continued warming of the Arctic may cause permafrost to thaw and speed the decomposition of large stores of soil organic carbon (OC), thereby accentuating global warming. However, it is unclear if recent warming has raised the current rates of permafrost OC release to anomalous levels or to what extent soil carbon release is sensitive to climate forcing. Here we use a time series of radiocarbon age-offsets ( 14 C) between the bulk lake sediment and plant macrofossils deposited in an arctic lake as an archive for soil and permafrost OC release over the last 14,500 years. The lake traps and archives OC imported from the watershed and allows us to test whether prior warming events stimulated old carbon release and heightened age-offsets. Today, the age-offset (2 ka; thousand of calibrated years before A.D. 1950) and the depositional rate of ancient OC from the watershed into the lake are relatively low and similar to those during the Younger Dryas cold interval (occurring 12.9-11.7 ka). In contrast, age-offsets were higher (3.0-5.0 ka) when summer air temperatures were warmer than present during the Holocene Thermal Maximum (11.7-9.0 ka) and Bølling-Allerød periods (14.5-12.9 ka). During these warm times, permafrost thaw contributed to ancient OC depositional rates that were~10 times greater than today. Although permafrost OC was vulnerable to climate warming in the past, we suggest surface soil organic horizons and peat are presently limiting summer thaw and carbon release. As a result, the temperature threshold to trigger widespread permafrost OC release is higher than during previous warming events.

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Quaternary glacial, lacustrine, and fluvial interactions in the western Noatak basin, Northwest Alaska

Cited by 37 publications

References 12 publications

Late Pleistocene mountain glaciation in Alaska: key chronologies

Late Pleistocene mountain glaciation in Alaska: key chronologies

Responses of an arctic landscape to Lateglacial and early Holocene climatic changes: the importance of moisture

Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change

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