Modelled composition of cryogenically produced subglacial brines, Antarctica

2019 ◽  
Vol 31 (3) ◽  
pp. 165-166 ◽  
Author(s):  
Christopher B. Gardner ◽  
W. Berry Lyons
Keyword(s):  
Dry Valleys ◽  
Important Process ◽  
Antarctic Ice Sheet ◽  
Lake Vostok ◽  
Hydrologic Systems ◽  
Victoria Land ◽  
Flow Through ◽  
Victoria Land Basin ◽  
Subglacial Meltwater ◽  
Permafrost Regions

Polar subglacial hydrologic systems have garnered much interest since the recognition of Lake Vostok in 1996. In Antarctica, these environments are hydrologically diverse, including isolated lakes of different sizes, river–lake flow-through systems, “swamps” and groundwater (Siegert 2016). The refreezing of subglacial meltwater is also an important process beneath a large portion of the East Antarctic Ice Sheet (Bell et al. 2011). As subglacial water refreezes it exsolves salts, potentially leaving behind saline and hypersaline brines. Brines thought to derive from this cryoconcentration process have been observed in the northern polar permafrost regions and in the McMurdo Dry Valleys (MDVs) region of Antarctica. Additionally, sediments in the Victoria Land Basin have diagenetic signatures produced by brine movement dating from 3–11 m.y.a, suggesting hypersaline brines have existed in the McMurdo region since at least this time (Staudigel et al. 2018).

scholarly journals Formation of thrust-block moraines at the margins of dry-based glaciers, south Victoria Land, Antarctica

1996 ◽  
Vol 22 ◽  
pp. 68-74 ◽  
Author(s):  
Sean J. Fitzsimons
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Freezing Point ◽  
Water Pressure ◽  
Lacustrine Sediment ◽  
Dry Valleys ◽  
Bed Deformation ◽  
Sedimentary Structures ◽  
Victoria Land ◽  
Subglacial Meltwater

Several dry-based alpine glaciers in the Dry Valleys of south Victoria Land, Antarctica, have prominent end moraines. Examination of their morphology, structure and sedimentology shows they consist of blocks of sand, gravel and organic silt within which sedimentary structures unrelated to entrainment and transportation by ice are well preserved. The nature and preservation of sedimentary structures, together with the presence of algae mats in the sediment, suggest formation by proglacial entrainment, transportation and deposition of frozen blocks of lacustrine sediment. Previous explanations of the formation of thrust-block moraines, including those that stress the importance of elevated pore-water pressure and Weertman’s ice-debris accretion hypothesis, depend on the presence of subglacial meltwater or the 0° C isotherm being situated close to the glacier bed. These models appear inappropriate for cold, dry-based glaciers because their basal temperatures are well below freezing point and they rest on deep permafrost. Three alternative models for the formation of thrust-block moraines at the margins of dry-based glaciers are examined in this paper: block entrainment of sediment associated with frozen-bed deformation; entrainment by overriding and accretion of marginal-ice and debris aprons; and transient wet-based conditions associated with glaciers flowing into ice-marginal lakes.

scholarly journals Formation of thrust-block moraines at the margins of dry-based glaciers, south Victoria Land, Antarctica

1996 ◽  
Vol 22 ◽  
pp. 68-74 ◽  
Author(s):  
Sean J. Fitzsimons
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Freezing Point ◽  
Water Pressure ◽  
Lacustrine Sediment ◽  
Dry Valleys ◽  
Bed Deformation ◽  
Sedimentary Structures ◽  
Victoria Land ◽  
Subglacial Meltwater

Several dry-based alpine glaciers in the Dry Valleys of south Victoria Land, Antarctica, have prominent end moraines. Examination of their morphology, structure and sedimentology shows they consist of blocks of sand, gravel and organic silt within which sedimentary structures unrelated to entrainment and transportation by ice are well preserved. The nature and preservation of sedimentary structures, together with the presence of algae mats in the sediment, suggest formation by proglacial entrainment, transportation and deposition of frozen blocks of lacustrine sediment. Previous explanations of the formation of thrust-block moraines, including those that stress the importance of elevated pore-water pressure and Weertman’s ice-debris accretion hypothesis, depend on the presence of subglacial meltwater or the 0° C isotherm being situated close to the glacier bed. These models appear inappropriate for cold, dry-based glaciers because their basal temperatures are well below freezing point and they rest on deep permafrost. Three alternative models for the formation of thrust-block moraines at the margins of dry-based glaciers are examined in this paper: block entrainment of sediment associated with frozen-bed deformation; entrainment by overriding and accretion of marginal-ice and debris aprons; and transient wet-based conditions associated with glaciers flowing into ice-marginal lakes.

Environmental magnetic record of Antarctic palaeoclimate from Eocene/Oligocene glaciomarine sediments, Victoria Land Basin

1998 ◽  
Vol 134 (3) ◽  
pp. 653-662 ◽  
Author(s):  
Leonardo Sagnotti ◽  
Fabio Florindo ◽  
Kenneth L. Verosub ◽  
Gary S. Wilson ◽  
Andrew P. Roberts
Keyword(s):  
Victoria Land ◽  
Magnetic Record ◽  
Victoria Land Basin ◽  
Glaciomarine Sediments

scholarly journals Antarctic ice sheet fertilises the Southern Ocean

2014 ◽  
Vol 11 (10) ◽  
pp. 2635-2643 ◽  
Author(s):  
R. Death ◽  
J. L. Wadham ◽  
F. Monteiro ◽  
A. M. Le Brocq ◽  
M. Tranter ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Ice Sheet ◽  
Ocean Model ◽  
Coastal Sediments ◽  
Global Ocean ◽  
Iron Cycling ◽  
Antarctic Ice Sheet ◽  
Significant Control ◽  
Subglacial Meltwater ◽  
The Impact

Abstract. Southern Ocean (SO) marine primary productivity (PP) is strongly influenced by the availability of iron in surface waters, which is thought to exert a significant control upon atmospheric CO2 concentrations on glacial/interglacial timescales. The zone bordering the Antarctic Ice Sheet exhibits high PP and seasonal plankton blooms in response to light and variations in iron availability. The sources of iron stimulating elevated SO PP are in debate. Established contributors include dust, coastal sediments/upwelling, icebergs and sea ice. Subglacial meltwater exported at the ice margin is a more recent suggestion, arising from intense iron cycling beneath the ice sheet. Icebergs and subglacial meltwater may supply a large amount of bioavailable iron to the SO, estimated in this study at 0.07–0.2 Tg yr−1. Here we apply the MIT global ocean model (Follows et al., 2007) to determine the potential impact of this level of iron export from the ice sheet upon SO PP. The export of iron from the ice sheet raises modelled SO PP by up to 40%, and provides one plausible explanation for seasonally very high in situ measurements of PP in the near-coastal zone. The impact on SO PP is greatest in coastal regions, which are also areas of high measured marine PP. These results suggest that the export of Antarctic runoff and icebergs may have an important impact on SO PP and should be included in future biogeochemical modelling.

Multiple cosmogenic nuclides document the stability of the East Antarctic Ice Sheet in northern Victoria Land since the Late Miocene (5–7 Ma)

2012 ◽  
Vol 57 ◽  
pp. 85-94 ◽  
Author(s):  
Luigia Di Nicola ◽  
Carlo Baroni ◽  
Stefan Strasky ◽  
Maria Cristina Salvatore ◽  
Christian Schlüchter ◽  
...  
Keyword(s):  
Late Miocene ◽  
Ice Sheet ◽  
Cosmogenic Nuclides ◽  
Antarctic Ice Sheet ◽  
Victoria Land ◽  
The Stability ◽  
East Antarctic Ice Sheet

East Antarctic Ice Sheet Sensitivity to Pliocene Climatic Change from a Dry Valleys Perspective

1993 ◽  
Vol 75 (4) ◽  
pp. 155 ◽  
Author(s):  
George H. Denton ◽  
David E. Sugden ◽  
David R. Marchant ◽  
Brenda L. Hall ◽  
Thomas I. Wilch
Keyword(s):  
Climatic Change ◽  
Ice Sheet ◽  
Dry Valleys ◽  
Antarctic Ice Sheet ◽  
East Antarctic Ice Sheet

scholarly journals Antarctic Ice Sheet fertilises the Southern Ocean

2013 ◽  
Vol 10 (7) ◽  
pp. 12551-12570 ◽  
Author(s):  
R. Death ◽  
J. L. Wadham ◽  
F. Monteiro ◽  
A. M. Le Brocq ◽  
M. Tranter ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Ice Sheet ◽  
Ocean Model ◽  
Coastal Sediments ◽  
Global Ocean ◽  
Iron Cycling ◽  
Antarctic Ice Sheet ◽  
Significant Control ◽  
Subglacial Meltwater ◽  
The Impact

Abstract. Southern Ocean (SO) marine primary productivity (PP) is strongly influenced by the availability of iron in surface waters, which is thought to exert a significant control upon atmospheric CO2 concentrations on glacial/interglacial timescales. The zone bordering the Antarctic Ice Sheet exhibits high PP and seasonal plankton blooms in response to light and variations in iron availability. The sources of iron stimulating elevated SO PP are in debate. Established contributors include dust, coastal sediments/upwelling, icebergs and sea ice. Subglacial meltwater exported at the ice margin is a more recent suggestion, arising from intense iron cycling beneath the ice sheet. Icebergs and subglacial meltwater may supply a large amount of bioavailable iron to the SO, estimated in this study at 0.07–1.0 Tg yr−1. Here we apply the MIT global ocean model (Follows et al., 2007) to determine the potential impact of this level of iron export from the ice sheet upon SO PP. The export of iron from the ice sheet raises modelled SO PP by up to 40%, and provides one plausible explanation for very high seasonally observed PP in the near-coastal zone. The impact on SO PP is greatest in coastal regions, which are also areas of high observed marine PP. These results suggest that the export of Antarctic runoff and icebergs may have an important impact on SO PP and should be included in future biogeochemical modelling.

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