Subglacial sediments: A regional geological template for ice flow in West Antarctica

Studinger, M.; Bell, Robin E.; Blankenship, D. D.; Finn, Carol A.; Arko, R. A.; Morse, D. L.; Joughin, Ian

doi:10.1029/2000gl011788

Cited by 103 publications

(137 citation statements)

References 16 publications

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“…In PD09 it was twovalued, depending on whether the modern rebounded Antarctic bedrock is above or below sea level: if above, C(x, y)=10 −10 m a −1 Pa −2 representing hard bedrock (mainly EAIS), and if below, C(x, y) = 10 −6 m a −1 Pa −2 representing deformable sediment (mainly WAIS) (e.g., Studinger et al, 2001) shown in Fig. 3a.…”

Section: Basal Sliding Coefficientsmentioning

confidence: 99%

Description of a hybrid ice sheet-shelf model, and application to Antarctica

2012

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Abstract. The formulation of a 3-D ice sheet-shelf model is described. The model is designed for long-term continentalscale applications, and has been used mostly in paleoclimatic studies. It uses a hybrid combination of the scaled shallow ice and shallow shelf approximations for ice flow. Floating ice shelves and grounding-line migration are included, with parameterized ice fluxes at grounding lines that allows relatively coarse resolutions to be used. All significant components and parameterizations of the model are described in some detail. Basic results for modern Antarctica are compared with observations, and simulations over the last 5 million years are compared with previously published results. The sensitivity of ice volumes during the last deglaciation to basal sliding coefficients is discussed.

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Section: Basal Sliding Coefficientsmentioning

confidence: 99%

Description of a hybrid ice sheet-shelf model, and application to Antarctica

2012

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“…Subglacial geology (e.g. the presence of deformable till) also influences the position of ice-stream margins (Anandakrishnan and others, 1998;Bell and others, 1998; Blankenship and others, 2001; Studinger and others, 2001). Most of Thwaites Glacier's tributaries clearly originate within bedrock troughs (Holt and others, 2006; Fig.…”

Section: Introductionmentioning

confidence: 99%

Weak bed control of the eastern shear margin of Thwaites Glacier, West Antarctica

MacGregor¹,

Catania

Conway

et al. 2013

J. Glaciol.

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ABSTRACT. Recent acceleration and thinning of Thwaites Glacier, West Antarctica, motivates investigation of the controls upon, and stability of, its present ice-flow pattern. Its eastern shear margin separates Thwaites Glacier from slower-flowing ice and the southern tributaries of Pine Island Glacier. Troughs in Thwaites Glacier's bed topography bound nearly all of its tributaries, except along this eastern shear margin, which has no clear relationship with regional bed topography along most of its length. Here we use airborne ice-penetrating radar data from the Airborne Geophysical Survey of the Amundsen Sea Embayment, Antarctica (AGASEA) to investigate the nature of the bed across this margin. Radar data reveal slightly higher and rougher bed topography on the slower-flowing side of the margin, along with lower bed reflectivity. However, the change in bed reflectivity across the margin is partially explained by a change in bed roughness. From these observations, we infer that the position of the eastern shear margin is not strongly controlled by local bed topography or other bed properties. Given the potential for future increases in ice flux farther downstream, the eastern shear margin may be vulnerable to migration. However, there is no evidence that this margin is migrating presently, despite ongoing changes farther downstream.

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“…[7] It is uncertain whether similar mechanisms act in the EAIS, because unlike the WAIS, most of East Antarctica is not grounded below sea level and so marine sediments may not be as widespread Blankenship et al, 1986;Joughin et al, 1999;Studinger et al, 2001]. Studies of East Antarctic ice dynamics are currently extremely under-represented in the literature, and there has been no investigation of the controls on enhanced flow here.…”

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“…From calculations of isostatically adjusted topography, it has been suggested that marine sediments, deposited before the formation of the West Antarctic Ice Sheet (WAIS), and during periods when the ice sheet collapsed, may be widespread in the Siple Coast region [Scherer et al, 1998;Studinger et al, 2001]. Additionally, aerogeophysical and seismic data from the tributaries of Ice Stream C and Whillans Ice Stream on the Siple Coast, have indicated that enhanced flow tributaries coincide well with sedimentary basins [Anandakrishnan et al, 1998;Bell et al, 1998;Blankenship et al, 2001;Studinger et al, 2001].…”

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confidence: 99%

“…[6] If basal motion is an important component of enhanced flow, then not only is a lubricating water layer necessary, but an easily erodable soft bed may also be important, since it has been suggested that rapid basal motion may be related to the presence of a basal layer of water-saturated dilatant till Blankenship et al, 1986;Studinger et al, 2001]. There is, however, uncertainty as to whether fast motion occurs by deformation of this till layer, or by sliding at the interface between ice and till Blankenship et al, 1987;Kamb, 1991Kamb, , 2001Tulaczyk et al, 2000aTulaczyk et al, , 2000bJoughin et al, 2002].…”

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Basal topography and ice flow in the Bailey/Slessor region of East Antarctica

et al. 2003

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An airborne radio‐echo sounding campaign carried out in the upper reaches of Bailey Ice Stream and Slessor Glacier, in Coats Land, East Antarctica, has revealed that tributaries of enhanced flow lie within well‐defined basal troughs and are separated from each other by bed highs. These new data indicate significant differences in ice thickness compared with those estimated in the Bedmap database. A numerical modeling study has revealed that driving stresses are high enough to account for flow by ice deformation alone in intertributary areas. Most flow in the enhanced flow tributaries of Slessor Glacier may also be explained by ice deformation alone. However, although ice deformation is also significant in the Bailey Ice Stream tributary, a large amount of basal motion is also required to fully explain flow velocities here. It is proposed that the trough in which Bailey tributary lies is sufficiently deep that marine sediments may have accumulated here in preglacial times. Along with water produced by geothermal heating, frictional heating, and through a reduction in the pressure melting point, basal motion may therefore be facilitated by the presence of a deformable, saturated till layer at the bed.

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Subglacial sediments: A regional geological template for ice flow in West Antarctica

Cited by 103 publications

References 16 publications

Description of a hybrid ice sheet-shelf model, and application to Antarctica

Description of a hybrid ice sheet-shelf model, and application to Antarctica

Weak bed control of the eastern shear margin of Thwaites Glacier, West Antarctica

Basal topography and ice flow in the Bailey/Slessor region of East Antarctica

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