Review of Persistent Tracers of Historic Ice Flow in Glacial Stratigraphy near Kamb Ice Stream

AbstractA basal zone, tens of meters thick, of debris-laden ice was observed in Kamb Ice Stream, West Antarctica, using a video camera lowered into boreholes made by hot-water drilling. The debris content varies, sometimes abruptly, forming a sequence of layers that reflect the complex history of fast ice flow and bed interaction. In most parts, the concentration of debris is low, a few percent by weight, with particles, often mud clots, dispersed in a matrix of clear ice. The nature of the debris distribution can be interpreted in terms of specific time intervals in the history of fast motion of Kamb Ice Stream including processes leading up to the termination of its streaming behavior and possible reactivation.

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Persistent tracers of historic ice flow in glacial stratigraphy near Kamb Ice Stream, West Antarctica

The Cryosphere ◽

10.5194/tc-12-2821-2018 ◽

2018 ◽

Vol 12 (9) ◽

pp. 2821-2829 ◽

Cited By ~ 2

Author(s):

Nicholas Holschuh ◽

Knut Christianson ◽

Howard Conway ◽

Robert W. Jacobel ◽

Brian C. Welch

Keyword(s):

Large Scale ◽

Ross Sea ◽

Accumulation Rate ◽

Volcanic Complex ◽

West Antarctica ◽

Ice Flow ◽

Ice Stream ◽

Grounding Line ◽

Flow Pathways ◽

Kamb Ice Stream

Abstract. Variations in properties controlling ice flow (e.g., topography, accumulation rate, basal friction) are recorded by structures in glacial stratigraphy. When anomalies that disturb the stratigraphy are fixed in space, the structures they produce advect away from the source and can be used to trace flow pathways and reconstruct ice-flow patterns of the past. Here we provide an example of one of these persistent tracers: a prominent unconformity in the glacial layering that originates at Mt. Resnik, part of a subglacial volcanic complex near Kamb Ice Stream in central West Antarctica. The unconformity records a change in the regional thinning behavior seemingly coincident (∼3440±117 a) with stabilization of grounding-line retreat in the Ross Sea Embayment. We argue that this feature records both the flow and thinning history far upstream of the Ross Sea grounding line, indicating a limited influence of observed ice-stream stagnation cycles on large-scale ice-sheet routing over the last ∼ 5700 years.

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Surface morphology and internal layer stratigraphy in the downstream end of Kamb Ice Stream, West Antarctica

Journal of Glaciology ◽

10.3189/172756505781829142 ◽

2005 ◽

Vol 51 (174) ◽

pp. 423-431 ◽

Cited By ~ 25

Author(s):

G. A. Catania ◽

H. Conway ◽

C.F. Raymond ◽

T.A. Scambos

Keyword(s):

Satellite Images ◽

Flow Direction ◽

Internal Layer ◽

Internal Layers ◽

West Antarctica ◽

Ice Flow ◽

Ice Stream ◽

Grounding Line ◽

Different Origins ◽

Kamb Ice Stream

AbstractSatellite images of Kamb Ice Stream (formerly Ice Stream C), West Antarctica, reveal several long, curved linear features (lineations) oriented sub-parallel to the ice-flow direction. We use ground-based radar to characterize the internal layer stratigraphy of these lineations and the terrains that they bound. Some lineations are relict ice-stream shear margins, identified by hyperbolic diffractors near the surface (interpreted to be buried crevasses) and highly disturbed internal layers at depth. Satellite images show another set of lineations outside the relict margins that wrap around the ends of the surrounding inter-ice-stream ridges. Internal layers beneath these lineations are downwarped strongly into a syncline shape. The internal stratigraphy of the terrain between these lineations and the relict margins is characterized by deep hyperbolic line diffractors. Our preferred hypothesis for the origin of this terrain is that it was floating sometime in the past; the deep hyperbolas are interpreted to be basal crevasses, and the strongly downwarped internal layers mark the position of a relict grounding line. Our study shows that lineations and intervening terrains have different internal layer characteristics implying different origins. Differentiation between these features is not possible using satellite images alone.

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Reactivation of Kamb Ice Stream tributaries triggers century-scale reorganization of Siple Coast ice flow in West Antarctica

Geophysical Research Letters ◽

10.1002/2015gl065782 ◽

2015 ◽

Vol 42 (20) ◽

pp. 8471-8480 ◽

Cited By ~ 16

Author(s):

M. Bougamont ◽

P. Christoffersen ◽

S. F. Price ◽

H. A. Fricker ◽

S. Tulaczyk ◽

...

Keyword(s):

West Antarctica ◽

Ice Flow ◽

Ice Stream ◽

Kamb Ice Stream

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Supplementary material to "Persistent Tracers of Historic Ice Flow in Glacial Stratigraphy near Kamb Ice Stream, West Antarctica"

10.5194/tc-2018-58-supplement ◽

2018 ◽

Author(s):

Nicholas Holschuh ◽

Knut Christianson ◽

Howard Conway ◽

Robert W. Jacobel ◽

Brian C. Welch

Keyword(s):

West Antarctica ◽

Ice Flow ◽

Ice Stream ◽

Supplementary Material ◽

Kamb Ice Stream

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Persistent Tracers of Historic Ice Flow in Glacial Stratigraphy near Kamb Ice Stream, West Antarctica

10.5194/tc-2018-58 ◽

2018 ◽

Author(s):

Nicholas Holschuh ◽

Knut Christianson ◽

Howard Conway ◽

Robert W. Jacobel ◽

Brian C. Welch

Keyword(s):

Large Scale ◽

Ross Sea ◽

Accumulation Rate ◽

Volcanic Complex ◽

West Antarctica ◽

Ice Flow ◽

Ice Stream ◽

Grounding Line ◽

Flow Pathways ◽

Kamb Ice Stream

Abstract. Variations in properties controlling ice flow (e.g., topography, accumulation rate, basal friction) are recorded by structures in glacial stratigraphy. When anomalies that disturb the stratigraphy are fixed in space, the structures they produce advect away from the source, and can be used to trace flow pathways and reconstruct ice-flow patterns of the past. Here we provide an example of one of these persistent tracers: a prominent unconformity in the glacial layering that originates at Mt. Resnik, part of a subglacial volcanic complex near Kamb Ice Stream in central West Antarctica. The unconformity records a change in the regional thinning behavior seemingly coincident (∼ 3440 ± 117a) with stabilization of grounding-line retreat along the Ross Ice Shelf. We argue that this feature records both the flow and thinning history far upstream of the Ross Sea grounding line, indicating a limited influence of observed ice-stream stagnation cycles on large-scale ice-sheet routing over the last ∼ 5700 years.

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Streamlined bedrock terrain and fast ice flow, Jakobshavns Isbrae, West Greenland: implications for ice stream and ice sheet dynamics

Boreas ◽

10.1080/03009480510012818 ◽

2005 ◽

Vol 34 (1) ◽

pp. 25-42 ◽

Cited By ~ 71

Author(s):

David H. Roberts ◽

Antony J. Long

Keyword(s):

Ice Sheet ◽

Ice Flow ◽

West Greenland ◽

Ice Stream ◽

Fast Ice ◽

Ice Sheet Dynamics

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Of isbræ and ice streams

Annals of Glaciology ◽

10.3189/172756403781816347 ◽

2003 ◽

Vol 36 ◽

pp. 66-72 ◽

Cited By ~ 88

Author(s):

Martin Truffer ◽

Keith A. Echelmeyer

Keyword(s):

Ice Sheet ◽

Shear Zones ◽

West Antarctica ◽

Ice Streams ◽

Ice Flow ◽

Bed Topography ◽

Ice Stream ◽

Fast Ice ◽

Fast Flow ◽

End Members

AbstractFast-flowing ice streams and outlet glaciers provide the major avenues for ice flow from past and present ice sheets. These ice streams move faster than the surrounding ice sheet by a factor of 100 or more. Several mechanisms for fast ice-stream flow have been identified, leading to a spectrum of different ice-stream types. In this paper we discuss the two end members of this spectrum, which we term the “ice-stream” type (represented by the Siple Coast ice streams in West Antarctica) and the “isbræ” type (represented by Jakobshavn Isbræ in Greenland). The typical ice stream is wide, relatively shallow (∼1000 m), has a low surface slope and driving stress (∼10 kPa), and ice-stream location is not strongly controlled by bed topography. Fast flow is possible because the ice stream has a slippery bed, possibly underlain by weak, actively deforming sediments. The marginal shear zones are narrow and support most of the driving stress, and the ice deforms almost exclusively by transverse shear. The margins seem to be inherently unstable; they migrate, and there are plausible mechanisms for such ice streams to shut down. The isbræ type of ice stream is characterized by very high driving stresses, often exceeding 200 kPa. They flow through deep bedrock channels that are significantly deeper than the surrounding ice, and have steep surface slopes. Ice deformation includes vertical as well as lateral shear, and basal motion need not contribute significantly to the overall motion. The marginal shear zone stend to be wide relative to the isbræ width, and the location of isbræ and its margins is strongly controlled by bedrock topography. They are stable features, and can only shut down if the high ice flux cannot be supplied from the adjacent ice sheet. Isbræs occur in Greenland and East Antarctica, and possibly parts of Pine Island and Thwaites Glaciers, West Antarctica. In this paper, we compare and contrast the two types of ice streams, addressing questions such as ice deformation, basal motion, subglacial hydrology, seasonality of ice flow, and stability of the ice streams.

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