scholarly journals Evidence for abundant subglacial meltwater beneath the paleo-ice sheet in Pine Island Bay, Antarctica

2003 ◽  
Vol 49 (164) ◽  
pp. 125-138 ◽  
Author(s):  
Ashley L. Lowe ◽  
John B. Anderson
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Drainage System ◽  
West Antarctic Ice Sheet ◽  
Sedimentary Deposits ◽  
West Antarctic ◽  
Crystalline Bedrock ◽  
Glacial Landforms ◽  
Subglacial Meltwater ◽  
Subglacial Drainage

AbstractMarine-geological and -geophysical data collected from the continental shelf in Pine Island Bay, Antarctica, reveal a complex paleo-subglacial drainage system controlled by bedrock topography and subglacial meltwater discharge. Significant amounts of freely flowing meltwater existed beneath former ice sheets in Pine Island Bay. Subglacial drainage is characterized by descriptions of glacial landforms imaged on the sea floor and sedimentary deposits collected in piston cores. Bedrock geology is characterized using seismic data. Large-scale landforms on the shelf include channels and cavities incised into impermeable crystalline bedrock. There is a transition from randomly oriented channels on the inner shelf to a dendritic pattern of elongate channels on the middle shelf. On the outer shelf, a change in basal conditions occurs where sedimentary deposits bury crystalline bedrock. No evidence for flowing meltwater exists on sedimentary substrates. Instead, meltwater formed at the ice–sediment contact was incorporated into the sediments, contributing to development of a deforming bed, which was sampled in piston cores. Characterization of subglacial meltwater processes that occurred in the past may aid in understanding the role meltwater plays in stability of the West Antarctic ice sheet today.

Large-scale integrated subglacial drainage around the former Keewatin Ice Divide, Canada reveals interaction between distributed and channelised systems

2020 ◽  
Author(s):  
Emma Lewington ◽  
Stephen Livingstone ◽  
Chris Clark ◽  
Andrew Sole ◽  
Robert Storrar
Keyword(s):  
Large Scale ◽  
Water Pressure ◽  
Pressure Fluctuations ◽  
Ice Sheet ◽  
Drainage System ◽  
Spatial Location ◽  
Variable Pressure ◽  
Ice Sheet Dynamics ◽  
Subglacial Meltwater ◽  
Subglacial Drainage

<p>Despite being widely studied, subglacial meltwater landforms are typically mapped and investigated individually, thus the drainage system as a whole remains poorly understood. Here, we identify and map all visible traces of subglacial meltwater flow across the Keewatin sector of the former Laurentide Ice Sheet from the ArcticDEM, generating significant new insights into the connectedness of the drainage system.</p><p>Due to similarities in spacing, morphometry and spatial location, we suggest that the 100s-1000s m wide features often flanking and connecting sections of eskers (i.e. tunnel valleys, meltwater tracks and esker splays) are varying expressions of the same phenomena and collectively term these features ‘meltwater corridors’. Based on observations from contemporary ice masses, we propose a new formation model based on the pressure fluctuations surrounding a central conduit, in which the esker records the imprint of the central conduit and the wider meltwater corridors the interactions with the surrounding distributed drainage system, or variable pressure axis (VPA).</p><p>We suggest that the widespread aerial coverage of meltwater corridors across the Keewatin sector provides constraints on the extent of basal uncoupling induced by basal water pressure fluctuation and variations in spatial distribution and evolution of the subglacial drainage system, which have important implications for ice sheet dynamics. </p>

scholarly journals Large-scale integrated subglacial drainage around the former Keewatin Ice Divide, Canada reveals interaction between distributed and channelised systems

2020 ◽  
Author(s):  
Emma L. M. Lewington ◽  
Stephen J. Livingstone ◽  
Chris D. Clark ◽  
Andrew J. Sole ◽  
Robert D. Storrar
Keyword(s):  
Spatial Distribution ◽  
Dynamic Response ◽  
Large Scale ◽  
Water Pressure ◽  
Pressure Fluctuations ◽  
Drainage System ◽  
Different Types ◽  
Form Part ◽  
Subglacial Meltwater ◽  
Subglacial Drainage

Abstract. We identify and map traces of subglacial meltwater drainage around the former Keewatin Ice Divide, Canada from ArcticDEM data. Meltwater tracks, tunnel valleys and esker splays exhibit several key similarities, including width, spacing, their association with eskers and transitions to and from different types, which together suggest they form part of an integrated drainage signature. We collectively term these features 'meltwater corridors' and propose a new model for their formation, based on observations from contemporary ice masses, of pressure fluctuations surrounding a central conduit. We suggest that eskers record the imprint of a central conduit and meltwater corridors the interaction with the surrounding distributed drainage system. The widespread aerial coverage of meltwater corridors (5–36 % of the bed) provides constraints on the extent of basal uncoupling induced by basal water pressure fluctuations and variations in spatial distribution and evolution of the subglacial drainage system, which will modulate the ice dynamic response.

scholarly journals A temperate former West Antarctic ice sheet suggested by an extensive zone of subglacial meltwater channels

Geology ◽  
2014 ◽  
Vol 42 (11) ◽  
pp. 971-974 ◽  
Author(s):  
Kathryn C. Rose ◽  
Neil Ross ◽  
Robert G. Bingham ◽  
Hugh F.J. Corr ◽  
Fausto Ferraccioli ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Subglacial Meltwater

scholarly journals West Antarctic sites for subglacial drilling to test for past ice-sheet collapse

2018 ◽  
Author(s):  
Perry Spector ◽  
John Stone ◽  
David Pollard ◽  
Trevor Hillebrand ◽  
Cameron Lewis ◽  
...  
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Cosmic Ray ◽  
West Antarctica ◽  
Maximum Information ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Field Reconnaissance ◽  
Marine Basins

Abstract. Mass loss from the West Antarctic Ice Sheet (WAIS) is increasing, and there is concern that an incipient large-scale deglaciation of the marine basins may already be underway. Measurements of cosmogenic nuclides in subglacial bedrock surfaces have the potential to establish whether and when the marine-based portions of the WAIS deglaciated in the past. However, because most of the bedrock revealed by ice-sheet collapse would remain below sea level, shielded from the cosmic-ray flux, drill sites for subglacial sampling must be located in areas where thinning of the residual ice sheet would expose presently subglacial bedrock surfaces. In this paper we discuss the criteria and considerations for choosing drill sites where subglacial samples will provide maximum information about WAIS extent during past interglacial periods. We evaluate candidate sites in West Antarctica and find that sites located adjacent to the large marine basins of West Antarctica will be most diagnostic of past ice-sheet collapse. There are important considerations for drill-site selection on the kilometer scale that can only be assessed by field reconnaissance. As a case study of these considerations, we describe reconnaissance at sites in West Antarctica, focusing on the Pirrit Hills, where in the summer of 2016–2017, an 8 m bedrock core was retrieved from below 150 m of ice.

Is the East Antarctic ice sheet stable?

2011 ◽  
Vol 75 (3) ◽  
pp. 417-429 ◽  
Author(s):  
Katherine Pingree ◽  
Max Lurie ◽  
Terence Hughes
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Drainage System ◽  
Ice Streams ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Global Sea Level ◽  
East Antarctic Ice Sheet

AbstractThe Greenland and East and West Antarctic ice sheets are assessed as being the source of ice that produced an Eemian sea level 6 m higher than present sea level. The most probable source is total collapse of the West Antarctic Ice Sheet accompanied by partial collapse of the adjacent sector of the East Antarctic Ice Sheet in direct contact with the West Antarctic Ice Sheet. This conclusion is reached by applying a simple formula relating the “floating fraction” of ice along flowlines to ice height above the bed. Increasing the floating fraction lowered ice elevations enough to contribute up to 4.7 m to global sea level. Adding 3.3 m resulting from total collapse of the West Antarctic Ice Sheet accounts for the higher Eemian sea level. Partial gravitational collapse that produced the present ice drainage system of Amery Ice Shelf contributes 2.3 m to global sea level. These results cast doubt on the presumed stability of the East Antarctic Ice Sheet, but destabilizing mechanisms remain largely unknown. Possibilities include glacial surges and marine instabilities at the respective head and foot of ice streams.

Subglacial Drainage Routes of the Last Scandinavian Ice Sheet

2020 ◽  
Author(s):  
Nico Dewald ◽  
Chris D. Clark ◽  
Stephen J. Livingstone ◽  
Jeremy C. Ely ◽  
Anna L.C. Hughes
Keyword(s):  
Large Scale ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Drainage Systems ◽  
Drainage Networks ◽  
Short Period ◽  
Scandinavian Ice Sheet ◽  
Subglacial Meltwater ◽  
Subglacial Drainage

<div> <div> <div> <p>The configuration of subglacial drainage systems has a major impact on the dynamics of ice sheets. However, the logistical challenges of measuring subglacial processes beneath contemporary ice sheets hinder our understanding about the spatio-temporal evolution of subglacial drainage systems. Furthermore, today’s observations on contemporary ice sheets are inherently limited to a short period within the process of deglaciation. Landforms generated by the flow of meltwater at the ice-bed interface offer the potential to study both large-scale (10<sup>3</sup>-10<sup>6</sup> km<sup>2</sup>) and long-term (10<sup>3</sup>-10<sup>5</sup> a) developments of subglacial drainage networks beneath past ice sheets. Despite collectively recording subglacial drainage, individual meltwater landform types such as eskers, meltwater channels and tunnel valleys, and hummock corridors have mostly been considered as separate entities. Using high-resolution (1-2 m) DEMs, we summarise the suite of interconnected subglacial meltwater landforms into a common drainage signature herein called a subglacial drainage route. Our integrated map of subglacial meltwater landforms presents the large-scale distribution of major subglacial drainage routes across Scandinavia and provides a basis for future research about the long-term evolution of subglacial drainage networks and its effect on ice dynamics of the Scandinavian Ice Sheet.</p> </div> </div> </div>

scholarly journals West Antarctic sites for subglacial drilling to test for past ice-sheet collapse

2018 ◽  
Vol 12 (8) ◽  
pp. 2741-2757 ◽  
Author(s):  
Perry Spector ◽  
John Stone ◽  
David Pollard ◽  
Trevor Hillebrand ◽  
Cameron Lewis ◽  
...  
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Cosmic Ray ◽  
West Antarctica ◽  
Maximum Information ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Field Reconnaissance ◽  
Marine Basins

Abstract. Mass loss from the West Antarctic Ice Sheet (WAIS) is increasing, and there is concern that an incipient large-scale deglaciation of the marine basins may already be underway. Measurements of cosmogenic nuclides in subglacial bedrock surfaces have the potential to establish whether and when the marine-based portions of the WAIS deglaciated in the past. However, because most of the bedrock revealed by ice-sheet collapse would remain below sea level, shielded from the cosmic-ray flux, drill sites for subglacial sampling must be located in areas where thinning of the residual ice sheet would expose presently subglacial bedrock surfaces. In this paper we discuss the criteria and considerations for choosing drill sites where subglacial samples will provide maximum information about WAIS extent during past interglacial periods. We evaluate candidate sites in West Antarctica and find that sites located adjacent to the large marine basins of West Antarctica will be most diagnostic of past ice-sheet collapse. There are important considerations for drill site selection on the kilometer scale that can only be assessed by field reconnaissance. As a case study of these considerations, we describe reconnaissance at sites in West Antarctica, focusing on the Pirrit Hills, where in the summer of 2016–2017 an 8 m bedrock core was retrieved from below 150 m of ice.

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