An analysis of the ice‐sheet surface and subsurface topography above the Vostok Station subglacial lake, central East Antarctica

Siegert, Martín J.; Ridley, Jeffrey K.

doi:10.1029/98jb00390

Cited by 48 publications

(46 citation statements)

References 18 publications

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“…The RES data show a distinct bending in the internal layering that can be modelled when zones of melting and freezing (in the order of several centimetres per year) are introduced. Internal layering features similar to those in Figure 2 occur across other parts of the western lake margin to the north of our flowline (Siegert and Ridley, 1998). If these RES features are also caused by zones of melting and freezing, then a continuous zone of basal melting may exist from our investigated flowline, northwards, along the western margin of the lake.…”

Section: Discussionmentioning

confidence: 91%

“…The RES profile (Fig. 2a) shows clear internal reflections in the ice which are interpreted as isochrons (Smith, 1996;Siegert and Ridley, 1998).…”

Section: Model Resultsmentioning

confidence: 99%

“…In central regions of East Antarctica, some of the most obvious surface morphological features result from ice flow over subglacial lakes. These basal water bodies, often hundreds to thousands of square kilometres in area, manifest themselves on the ice-sheet surface as distinct smooth, flat regions (Cudlip and McIntyre, 1987;Ridley and others, 1993;Kapitsa and others, 1996;Siegert and Ridley, 1998). However, the influence of subglacial lakes on ice dynamics has yet to be quantified fully.…”

Section: Introductionmentioning

confidence: 99%

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Numerical modelling of ice-sheet dynamics across the Vostok subglacial lake, central East Antarctica

Mayer

Siegert

2000

J. Glaciol.

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ABSTRACT. A numerical model of the ice-sheet/ice-shelf transition was used to investigate ice-sheet dynamics across the large subglacial lake beneath Vostok station, central East Antarctica. European Remote-sensing Satellite (ERS-1) altimetry of the ice surface and 60 MHz radio-echo sounding (RES) of the ice-sheet base and internal ice-sheet layering were used to develop a conceptual flowline across the ice sheet, which the model used as input. The model calculates horizontal and vertical velocities and stresses, from which particle flow paths can be obtained, and the ice-sheet temperature distribution. An inverse approach to modelling was adopted, where particle flow paths were forced to match those identified from internal RES layering. Results show that ice dynamics across the inflow grounding line are similar to an ice-sheet/ice-shelf transition. Model particle flow paths match internal RES layering when ice is (a) taken away from the ice base across the first 2 km of the flowline over the lake and (b) added to the base across the remainder of the lake. We contend that the process causing this transfer of ice is likely to be melting of ice and freezing of water at the ice^water interface. Other explanations, such as enhanced rates of accumulation over the grounding line, or three-dimensional convergent/divergent flow of ice are inconsistent with available measurements. Such melting and refreezing would be responsible for circulation and mixing of at least the surface layers of the lake water. Our model suggests that several tens of metres of refrozen``basal ice'' would accrete from lake water to the ice sheet before the ice regrounds.

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Section: Discussionmentioning

confidence: 91%

“…The RES profile (Fig. 2a) shows clear internal reflections in the ice which are interpreted as isochrons (Smith, 1996;Siegert and Ridley, 1998).…”

Section: Model Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical modelling of ice-sheet dynamics across the Vostok subglacial lake, central East Antarctica

Mayer

Siegert

2000

J. Glaciol.

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“…A subglacial lake the size of Lake Ontario would have significantly influenced the surface topography of the overlying ice sheet in a fashion similar to that documented from the Antarctica Ice Sheet (Siegert and Ridley, 1998). The largest documented subglacial lake beneath the Antarctic Ice Sheet is Lake Vostok and is overlain by ice with a surface topography of 0.004°slope (0.25 m km -1 ; Siegert 2000).…”

Section: The Confining Ice Lidmentioning

confidence: 99%

Stratigraphic Architecture and Sediment Facies of the Western Oak Ridges Moraine, Humber River Watershed, Southern Ontario*

Russell

Arnott

Sharpe

2006

gpq

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The Oak Ridges Moraine in southern Ontario is a ca. 160 km long east-west trending ridge of sand and gravel situated north of Lake Ontario. Study of the Oak Ridges Moraine in the Humber River watershed was undertaken to assess its role in the groundwater system of the buried Laurentian Valley. The Oak Ridges Moraine is interpreted to have been deposited in three stages. Stage I records rapid deposition from hyperconcentrated flows where tunnel channels discharged into a subglacial lake in the Lake Ontario basin. Low-energy basin sedimentation of Stage II was in a subglacial and ice-contact setting of a highly crevassed ice sheet. Stage III sedimentation is characterized by rapid facies changes associated with esker, subaqueous fan, and basinal sedimentation. Detailed sediment analysis challenges the concept that the Oak Ridges Moraine was deposited principally from seasonal meltwater discharges, climatic modulated ice-marginal fluctuations, or in an interlobate position. Instead it is interpreted to have formed in response to late-glacial ice sheet events associated with subglacial meltwater ponding, episodic and catastrophic subglacial meltwater discharge, and subsequent seasonal meltwater discharge. The moraine probably formed as the glacial-hydraulic system re-equilibrated to the presence of a thinned, grounded ice shelf and a subglacial lake in the Lake Ontario basin.La moraine de Oak Ridges, sud de l’Ontario, est une crête de sable et de gravier orientée est-ouest d’une longueur de 160 km au nord du lac Ontario. L’étude de la moraine de Oak Ridges dans le bassin de la rivière Humber permet de comprendre son rôle dans le système de drainage de la vallée Laurentienne. La moraine de Oak Ridges a été édifiée en trois phases. La phase I consiste en une sédimentation rapide par hyperconcentration des écoulements, où les chenaux en tunnel se déversent dans un lac sous-glaciaire du lac Ontario. Le bassin de sédimentation de faible énergie de la phase II est sous-glaciaire et touche à un inlandsis ayant d’importantes crevasses. La phase III se caractérise par un changement de faciès très rapide, par la présence d’eskers, de cônes aquatiques et de bassins sédimentaires. Les analyses sédimentaires détaillées ébranlent l’hypothèse que la moraine de Oak Ridges ait été formée par la fonte des glaces saisonnière, les fluctuations climatiques près des marges glaciaires, ou dans une position interlobaire. Notre interprétation indique plutôt qu’elle a été mise en place en réponse à des événements de fonte sous-glaciaire de nature épisodique et catastrophique, et par des apports subséquents d’eau de fonte saisonnière. La moraine s’est probablement formée lors de la ré-équilibration du système glacio-hydraulique en présence d’un inlandsis mince, en contact avec le substrat et alimentant un lac sous-glaciaire dans le bassin du lac Ontario

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“…From airborne radar data, Siegert and Ridley [1998] demonstrated that the ice sheet first thins, then thickens, as the ice cross es the lake. These changes appear to be driv en by the melting and refreezing processes at the base of the ice sheet.…”

Section: Clearly Visible From Spacementioning

confidence: 99%

Evolutionary processes a focus of decade‐long ecosystem study of Antarctic's Lake Vostok

Bell

Karl

1999

EoS Transactions

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As scientists probe for life in new habitats and try to understand the processes that triggered the origin and guided the evolution of life on Earth, environments beneath large ice sheets are beginning to emerge as key ecosystems. Modern subglacial environments are analogues both for the icy moons of Jupiter and the environmental stresses that led to widespread evolutionary radiation following the Neoproterozoic “snowball” Earth. The largest modern analogue to these distant systems is Lake Vostok, a great Antarctic subglacial lake, and the international science community is developing a plan to systematically survey and explore this complex system over the next decade. Approximately the size of Lake Ontario, Lake Vostok lies beneath the 4 km thick East Antarctic ice sheet (Figure 1). The lake is much deeper than Lake Ontario—remotely measured water depths reach 670 m.

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An analysis of the ice‐sheet surface and subsurface topography above the Vostok Station subglacial lake, central East Antarctica

Cited by 48 publications

References 18 publications

Numerical modelling of ice-sheet dynamics across the Vostok subglacial lake, central East Antarctica

Numerical modelling of ice-sheet dynamics across the Vostok subglacial lake, central East Antarctica

Stratigraphic Architecture and Sediment Facies of the Western Oak Ridges Moraine, Humber River Watershed, Southern Ontario*

Evolutionary processes a focus of decade‐long ecosystem study of Antarctic's Lake Vostok

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