Distribution of marine ice beneath the Amery Ice Shelf

Fricker, H. A.; Попов, С. В.; Allison, Ian; Young, Neal W.

doi:10.1029/2000gl012461

Cited by 143 publications

(213 citation statements)

References 19 publications

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“…Surface elevation corresponds well to the free-board height derived from locally averaged ice thickness over length scales on the order of 10 ice thicknesses (Figure 2a), and there was no evidence for a thick marine-ice layer from the oceanic borehole at M2. In the 10 MHz radar profiles, we see a bright continuous basal interface typical for a meteoric ice-ocean interface [Fricker et al, 2001]. Furthermore, a significant marine-ice layer (> 8 m, the vertical radar resolution) would be detectable with the low-frequency radar as a deeper fainter continuous interface [Blindow, 1994], which we do not observe.…”

Section: Resultsmentioning

confidence: 72%

Complex network of channels beneath an Antarctic ice shelf

Langley

Deschwanden

Kohler

et al. 2014

Geophysical Research Letters

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Ice shelves play an important role in stabilizing the interior grounded ice of the large ice sheets.The thinning of major ice shelves observed in recent years, possibly in connection to warmer ocean waters coming into contact with the ice-shelf base, has focused attention on the ice-ocean interface. Here we reveal a complex network of sub ice-shelf channels under the Fimbul Ice Shelf, Antarctica, mapped using ground-penetrating radar over a 100 km 2 grid. The channels are 300-500 m wide and 50 m high, among the narrowest of any reported. Observing narrow channels beneath an ice shelf that is mainly surrounded by cold ocean waters, with temperatures close to the surface freezing point, shows that channelized basal melting is not restricted to rapidly melting ice shelves, indicating that spatial melt patterns around Antarctica are likely to vary on scales that are not yet incorporated in ice-ocean models.

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Section: Resultsmentioning

confidence: 72%

Complex network of channels beneath an Antarctic ice shelf

Langley

Deschwanden

Kohler

et al. 2014

Geophysical Research Letters

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“…1). Greater depths (> 2200 m, Fricker et al 2001) are found near the present ice shelf grounding zone well inland (550 km) from Prydz Bay (Fricker et al 2002). The Amery Depression is linked to the shelf edge by the Prydz Channel, which occupies the western part of the bay and has depths from 700 m below sea level at its inshore end to about 500 m below sea level at the shelf edge (Fig.…”

Section: Regional Settingmentioning

confidence: 99%

History of benthic colonisation beneath the Amery Ice Shelf, East Antarctica

Post¹,

Hemer²,

O'Brien³

et al. 2007

Mar. Ecol. Prog. Ser.

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This study presents compelling evidence for a diverse and abundant seabed community that developed over the course of the Holocene beneath the Amery Ice Shelf, East Antarctica. Fossil analysis of a 47 cm long sediment core revealed a rich modern fauna dominated by filter feeders (sponges and bryozoans). The down-core assemblage indicated a succession in the colonisation of this site. The lower portion of the core (before ~9600 yr BP) was completely devoid of preserved fauna. The first colonisers (at ~10 200 yr BP) were mobile benthic organisms. Their occurrence was matched by the first appearance of planktonic taxa, indicating a retreat of the ice shelf following the last glaciation to within sufficient distance to advect planktonic particles via bottom currents. The benthic infauna and filter feeders emerged during the peak abundance of the planktonic organisms, indicating their dependence on the food supply sourced from the open shelf waters of Prydz Bay. Understanding patterns of species succession in this environment has important implications for determining the potential significance of future ice shelf collapse.

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“…Ocean circulation and water temperature underneath ice shelves are critical for the ice mass balance; basal accretion amounting to as much as 190 m of ice from the grounding line to the calving front is observed underneath the Amery Ice Shelf in eastern Antarctica (Fricker et al, 2001). On the other hand, warm water has been shown to protrude onto the Amundsen Sea continental shelf in West Antarctica, causing thinning of the floating margin of Pine Island Glacier (Walker et al, 2007;Wåhlin et al, in press).…”

Section: Introductionmentioning

confidence: 99%

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

119

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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Distribution of marine ice beneath the Amery Ice Shelf

Cited by 143 publications

References 19 publications

Complex network of channels beneath an Antarctic ice shelf

Complex network of channels beneath an Antarctic ice shelf

History of benthic colonisation beneath the Amery Ice Shelf, East Antarctica

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

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