scholarly journals Kamb Ice Stream flow history and surge potential

2013 ◽  
Vol 54 (63) ◽  
pp. 287-298 ◽  
Author(s):  
Hermann Engelhardt ◽  
Barclay Kamb
Keyword(s):  
Video Camera ◽  
Hot Water ◽  
West Antarctica ◽  
Time Intervals ◽  
Ice Flow ◽  
Ice Stream ◽  
History Of ◽  
Fast Ice ◽  
Fast Motion ◽  
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.

scholarly journals Ice stream subglacial access for ice-sheet history and fast ice flow: the BEAMISH Project on Rutford Ice Stream, West Antarctica and initial results on basal conditions

2020 ◽  
pp. 1-9
Author(s):  
A. M. Smith ◽  
P. G. D. Anker ◽  
K. W. Nicholls ◽  
K. Makinson ◽  
T. Murray ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Hot Water ◽  
Ice Flow ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Ice Stream ◽  
Hydrological System ◽  
History Of ◽  
Fast Ice ◽  
Water Saturated

Abstract Three holes were drilled to the bed of Rutford Ice Stream, through ice up to 2154 m thick, to investigate the basal processes and conditions associated with fast ice flow and the glacial history of the West Antarctic Ice Sheet. A narrative of the drilling, measuring and sampling activities, as well as some preliminary results and initial interpretations of subglacial conditions, is given. These were the deepest subglacial access holes ever drilled using the hot-water drilling method. Samples of bed and englacial sediments were recovered, and a number of instruments were installed in the ice column and the bed. The ice–bed interface was found to be unfrozen, with an existing, well-developed subglacial hydrological system at high pressure, within ~1% of the ice overburden. The bed itself comprises soft, water-saturated sediments, consistent with previous geophysical interpretations. Englacial sediment quantity varies significantly between two locations ~2 km apart, and possibly over even shorter (~20 m) distances. Difficulties and unusual observations encountered while connecting to the subglacial hydrological system in one hole possibly resulted from the presence of a large clast embedded in the bottom of the ice.

scholarly journals Of isbræ and ice streams

2003 ◽  
Vol 36 ◽  
pp. 66-72 ◽  
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.

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

2018 ◽  
Vol 12 (9) ◽  
pp. 2821-2829 ◽  
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.

scholarly journals New and improved determinations of velocity of Ice Streams B and C, West Antarctica

1993 ◽  
Vol 39 (133) ◽  
pp. 483-590 ◽  
Author(s):  
I. M. Whillans ◽  
C.J. Van Der Veen
Keyword(s):  
Stream Flow ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Streams ◽  
Ice Flow ◽  
Ice Stream ◽  
Fast Ice ◽  
Ice Stream B ◽  
Shelf Flow ◽  
Streaming Flow

AbstractMeasurements of velocity have been made on and next to Ice Streams Β and C, West Antarctica. The results are more precise than previous work and constitute a 93% increase in the number of values. These velocities are used to describe the confluence of flow into the ice streams and the development of fast ice-stream flow. The onset of fast-streaming flow occurs in many separate tributaries that coalesce down-glacier into the major ice streams. For those inter-stream ridges that have been studied, the flow is consistent with steady state. Along Ice Stream B, gradients in longitudinal stress offer little resistance to the ice flow. The transition from basal-drag control to ice-shelf flow is achieved through reduced drag at the glacier base and increased resistance associated with lateral drag. Velocities in the trunk of Ice Stream C are nearly zero but those at the up-glacial head are similar to those at the head of Ice Stream B.

scholarly journals New and improved determinations of velocity of Ice Streams B and C, West Antarctica

1993 ◽  
Vol 39 (133) ◽  
pp. 483-590 ◽  
Author(s):  
I. M. Whillans ◽  
C.J. Van Der Veen
Keyword(s):  
Stream Flow ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Streams ◽  
Ice Flow ◽  
Ice Stream ◽  
Fast Ice ◽  
Ice Stream B ◽  
Shelf Flow ◽  
Streaming Flow

Abstract Measurements of velocity have been made on and next to Ice Streams Β and C, West Antarctica. The results are more precise than previous work and constitute a 93% increase in the number of values. These velocities are used to describe the confluence of flow into the ice streams and the development of fast ice-stream flow. The onset of fast-streaming flow occurs in many separate tributaries that coalesce down-glacier into the major ice streams. For those inter-stream ridges that have been studied, the flow is consistent with steady state. Along Ice Stream B, gradients in longitudinal stress offer little resistance to the ice flow. The transition from basal-drag control to ice-shelf flow is achieved through reduced drag at the glacier base and increased resistance associated with lateral drag. Velocities in the trunk of Ice Stream C are nearly zero but those at the up-glacial head are similar to those at the head of Ice Stream B.

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

2005 ◽  
Vol 51 (174) ◽  
pp. 423-431 ◽  
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.

scholarly journals Interpreting englacial layer deformation in the presence of complex ice flow history with synthetic radargrams

2020 ◽  
Vol 61 (81) ◽  
pp. 206-213 ◽  
Author(s):  
Cooper W. Elsworth ◽  
Dustin M. Schroeder ◽  
Matthew R. Siegfried
Keyword(s):  
Layer Structure ◽  
Geophysical Methods ◽  
West Antarctica ◽  
Ice Dynamics ◽  
Ice Flow ◽  
Ice Stream ◽  
Whillans Ice Stream ◽  
Antarctic Continent ◽  
Fast Ice ◽  
The Antarctic

AbstractFast ice flow on the Antarctic continent constitutes much of the mass loss from the ice sheet. However, geophysical methods struggle to constrain ice flow history at depth, or separate the signatures of topography, ice dynamics and basal conditions on layer structure. We develop and demonstrate a methodology to compare layer signatures in multiple airborne radar transects in order to characterize ice flow at depth, or improve coverage of existing radar surveys. We apply this technique to generate synthetic, along-flow radargrams and compare different deformation regimes to observed radargram structure. Specifically, we investigate flow around the central sticky spot of Whillans Ice Stream, West Antarctica. Our study suggests that present-day velocity flowlines are insufficient to characterize flow at depth as expressed in layer geometry, and streaklines provide a better characterization of flow around a basal sticky spot. For Whillans Ice Stream, this suggests that ice flow wraps around the central sticky spot, supported by idealized flow simulations. While tracking isochrone translation and rotation across survey lines is complex, we demonstrate that our approach to combine radargram interpretation and modeling can reveal critical details of past ice flow.

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

2015 ◽  
Vol 42 (20) ◽  
pp. 8471-8480 ◽  
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

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

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

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

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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