Seafloor evidence for ice shelf flow across the Alaska–Beaufort margin of the Arctic Ocean

Engels, Jennifer; Polyak, Leonid; Johnson, Paul

doi:10.1002/esp.1601

Cited by 43 publications

(53 citation statements)

References 52 publications

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“…Previous studies of the Chukchi Borderland suggest the re-current influence of ice grounding attributed to ice shelves extending from the northern margin of the Laurentide Ice Sheet combined with an ice rise formed over the borderland (Jakobsson et al, 2008b). This is corroborated by traces of ice shelf grounding along the Alaska-Beaufort margin (Engels et al, 2007). Furthermore, the flat topped nature of the southern Lomonosov Ridge north of Greenland and the data presented here indicate extensive ice grounding and the possible formation of local ice rises in this area.…”

Section: An Arctic Ocean Ice Shelf In the Amerasian Basinmentioning

confidence: 70%

“…2c). Orientations of glaciogenic features found on the Alaska-Beaufort Margin (Engels et al, 2007), suggest that ice masses may first have extended from the northwestern margin of the Laurentide Ice Sheet to the Chukchi Borderland forming the nucleus of a local ice rise, which eventually may have developed into its own ice sheet.…”

Section: Geophysical Mappingmentioning

confidence: 99%

“…comm.). The general maximum seaward limit is defined where the ice shelf thins to a thickness of 200 m. The only exception is the Beaufort Sea area, where there are signs of ice shelf grounding along the continental margin (Engels et al, 2007).…”

Section: An Arctic Ocean Ice Shelf In the Amerasian Basinmentioning

confidence: 99%

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An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data

Nilsson

O’Regan

Backman

et al. 2010

Quaternary Science Reviews

Self Cite

114

118

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a b s t r a c tThe hypothesis of floating ice shelves covering the Arctic Ocean during glacial periods was developed in the 1970s. In its most extreme form, this theory involved a 1000 m thick continuous ice shelf covering the Arctic Ocean during Quaternary glacial maxima including the Last Glacial Maximum (LGM). While recent observations clearly demonstrate deep ice grounding events in the central Arctic Ocean, the ice shelf hypothesis has been difficult to evaluate due to a lack of information from key areas with severe sea ice conditions. Here we present new data from previously inaccessible, unmapped areas that constrain the spatial extent and timing of marine ice sheets during past glacials. These data include multibeam swath bathymetry and subbottom profiles portraying glaciogenic features on the Chukchi Borderland, southern Lomonosov Ridge north of Greenland, Morris Jesup Rise, and Yermak Plateau. Sediment cores from the mapped areas provide age constraints on the glaciogenic features. Combining these new geophysical and geological data with earlier results suggests that an especially extensive marine ice sheet complex, including an ice shelf, existed in the Amerasian Arctic Ocean during Marine Isotope Stage (MIS) 6. From a conceptual oceanographic model we speculate that the cold halocline of the Polar Surface Water may have extended to deeper water depths during MIS 6 inhibiting the warm Atlantic water from reaching the Amerasian Arctic Ocean and, thus, creating favorable conditions for ice shelf development. The hypothesis of a continuous 1000 m thick ice shelf is rejected because our mapping results show that several areas in the central Arctic Ocean substantially shallower than 1000 m water depth are free from glacial influence on the seafloor.

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Section: An Arctic Ocean Ice Shelf In the Amerasian Basinmentioning

confidence: 70%

Section: Geophysical Mappingmentioning

confidence: 99%

See 1 more Smart Citation

An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data

Nilsson

O’Regan

Backman

et al. 2010

Quaternary Science Reviews

Self Cite

114

118

View full text Add to dashboard Cite

show abstract

“…Recent geophysical mapping in the Arctic, however, has led to a re-evaluation of large floating Arctic ice shelves during the Pleistocene. Various mechanisms have been proposed to account for the mapped submarine features, including the drifting of ice-shelf remnants or mega-bergs trapped in multi-year sea ice, or a transient surge or brief grounding of a floating ice shelf (Polyak et al, 2001(Polyak et al, , 2009Engels et al, 2008;Dowdeswell et al, 2010;O'Regan et al, 2010;Gebhardt et al, 2011;Niessen et al, 2013;Dove et al, 2014). Age control for many of the features remains enigmatic, often relying on stratigraphic correlation and biostratigraphy; for example, identification of diagnostic MIS 5e nannofossils gives a likely, or minimum, MIS 6 age estimate for features on Morris Jesup Rise, Lomonosov Ridge, Yermak Plateau, Hovgaard Ridge, Mendeleev Ridge, and Arlis Plateau (Jakobsson, 1999;Polyak et al, 2001;Matthiessen and Knies, 2001;Kristoffersen et al, 2004;Spielhagen et al, 2004;Jakobsson et al, 2008Jakobsson et al, , 2010Jakobsson et al, , 2016Arndt et al, 2014;L€ owemark et al, 2016).…”

Section: The Global D 18 O:sea-level/ice-volume Relationshipmentioning

confidence: 99%

“…Age control for many of the features remains enigmatic, often relying on stratigraphic correlation and biostratigraphy; for example, identification of diagnostic MIS 5e nannofossils gives a likely, or minimum, MIS 6 age estimate for features on Morris Jesup Rise, Lomonosov Ridge, Yermak Plateau, Hovgaard Ridge, Mendeleev Ridge, and Arlis Plateau (Jakobsson, 1999;Polyak et al, 2001;Matthiessen and Knies, 2001;Kristoffersen et al, 2004;Spielhagen et al, 2004;Jakobsson et al, 2008Jakobsson et al, , 2010Jakobsson et al, , 2016Arndt et al, 2014;L€ owemark et al, 2016). Debate continues not only about the age of the submarine features (e.g., Flower, 1997;Niessen et al, 2013), but also about the scale of any ice shelves, from Arcticwide as proposed by Hughes et al (1977) and more recently by Jakobsson et al (2016), to (much) more limited extents (Engels et al, 2008;Jakobsson et al, 2010;Niessen et al, 2013;Stein et al, 2017).…”

Section: The Global D 18 O:sea-level/ice-volume Relationshipmentioning

confidence: 99%

Differences between the last two glacial maxima and implications for ice-sheet, δ18O, and sea-level reconstructions

Rohling

Hibbert

Williams

et al. 2017

Quaternary Science Reviews

115

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Arctic ice shelf Last Interglacial Glacioisostatic adjustment a b s t r a c t Studies of past glacial cycles yield critical information about climate and sea-level (ice-volume) variability, including the sensitivity of climate to radiative change, and impacts of crustal rebound on sealevel reconstructions for past interglacials. Here we identify significant differences between the last and penultimate glacial maxima (LGM and PGM) in terms of global volume and distribution of land ice, despite similar temperatures and radiative forcing. Our analysis challenges conventional views of relationships between global ice volume, sea level, seawater oxygen isotope values, and deep-sea temperature, and supports the potential presence of large floating Arctic ice shelves during the PGM. The existence of different glacial 'modes' calls for focussed research on the complex processes behind ice-age development. We present a glacioisostatic assessment to demonstrate how a different PGM ice-sheet configuration might affect sea-level estimates for the last interglacial. Results suggest that this may alter existing last interglacial sea-level estimates, which often use an LGM-like ice configuration, by several metres (likely upward).

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Widespread gas hydrate instability on the upper U.S. Beaufort margin

et al. 2014

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The most climate-sensitive methane hydrate deposits occur on upper continental slopes at depths close to the minimum pressure and maximum temperature for gas hydrate stability. At these water depths, small perturbations in intermediate ocean water temperatures can lead to gas hydrate dissociation. The Arctic Ocean has experienced more dramatic warming than lower latitudes, but observational data have not been used to study the interplay between upper slope gas hydrates and warming ocean waters. Here we use (a) legacy seismic data that constrain upper slope gas hydrate distributions on the U.S. Beaufort Sea margin, (b) Alaskan North Slope borehole data and offshore thermal gradients determined from gas hydrate stability zone thickness to infer regional heat flow, and (c) 1088 direct measurements to characterize multidecadal intermediate ocean warming in the U.S. Beaufort Sea. Combining these data with a three-dimensional thermal model shows that the observed gas hydrate stability zone is too deep by 100 to 250 m. The disparity can be partially attributed to several processes, but the most important is the reequilibration (thinning) of gas hydrates in response to significant (~0.5°C at 2σ certainty) warming of intermediate ocean temperatures over 39 years in a depth range that brackets the upper slope extent of the gas hydrate stability zone. Even in the absence of additional ocean warming, 0.44 to 2.2 Gt of methane could be released from reequilibrating gas hydrates into the sediments underlying an area of~5-7.5 × 10 3 km 2 on the U.S. Beaufort Sea upper slope during the next century.

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Seafloor evidence for ice shelf flow across the Alaska–Beaufort margin of the Arctic Ocean

Cited by 43 publications

References 52 publications

An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data

An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data

Differences between the last two glacial maxima and implications for ice-sheet, δ18O, and sea-level reconstructions

Widespread gas hydrate instability on the upper U.S. Beaufort margin

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