scholarly journals An englacial hydrologic system of brine within a cold glacier: Blood Falls, McMurdo Dry Valleys, Antarctica

2017 ◽  
Vol 63 (239) ◽  
pp. 387-400 ◽  
Author(s):  
JESSICA A. BADGELEY ◽  
ERIN C. PETTIT ◽  
CHRISTINA G. CARR ◽  
SLAWEK TULACZYK ◽  
JILL A. MIKUCKI ◽  
...  
Keyword(s):  
Latent Heat ◽  
Flow Direction ◽  
Salt Content ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Outlet Glacier ◽  
Air Temperatures ◽  
Radio Echo Sounding ◽  
Hydrologic System ◽  
Taylor Glacier

ABSTRACTTaylor Glacier hosts an active englacial hydrologic system that feeds Blood Falls, a supraglacial outflow of iron-rich subglacial brine at the terminus, despite mean annual air temperatures of −17°C and limited surface melt. Taylor Glacier is an outlet glacier of the East Antarctic ice sheet that terminates in Lake Bonney, McMurdo Dry Valleys. To image and map the brine feeding Blood Falls, we used radio echo sounding to delineate a subhorizontal zone of englacial brine upstream from Blood Falls and elongated in the ice flow direction. We estimate volumetric brine content in excess of 13% within 2 m of the central axis of this zone, and likely much higher at its center. Brine content decreases, but remains detectable, up to 45 m away along some transects. Hence, we infer a network of subparallel basal crevasses allowing injection of pressurized subglacial brine into the ice. Subglacial brine is routed towards Blood Falls by hydraulic potential gradients associated with deeply incised supraglacial valleys. The brine remains liquid within the subglacial and englacial environments through latent heat of freezing coupled with elevated salt content. Our findings suggest that cold glaciers could support freshwater hydrologic systems through localized warming by latent heat alone.

scholarly journals The climate history of early Mars: insights from the Antarctic McMurdo Dry Valleys hydrologic system

2014 ◽  
Vol 26 (6) ◽  
pp. 774-800 ◽  
Author(s):  
James W. Head ◽  
David R. Marchant
Keyword(s):  
Ground Surface ◽  
Volcanic Eruptions ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Climate History ◽  
Air Temperatures ◽  
Hydrological System ◽  
Hydrologic System ◽  
Early Mars ◽  
Geologic Record

AbstractThe early climate of Mars (Noachian Period, the first ~20% of its history) is thought to differ significantly from that of its more recent history (Amazonian Period, the last ~66%) which is characterized by hyperarid, hypothermal conditions that result in mean annual air temperatures (MAAT) well below 0°C, a global cryosphere, minimal melting on the ground surface, and a horizontally stratified hydrologic system. We explore the nature of the fluvial and lacustrine environments in the Mars-like hyperarid, hypothermal McMurdo Dry Valleys (MDV), where the MAAT is well below 0°C (~ -14 to -30°C) in order to assess whether the Late Noachian geologic record can be explained by a climate characterized by “cold and icy” conditions. We find that the MDV hydrological system and cycle provide important insights into the potential configuration of a “cold and icy” early Mars climate in which MDV-like ephemeral streams and rivers, and both closed-basin and open-basin lakes could form. We review a series of MDV fluvial and lacustrine features to guide investigators in the analysis of the geomorphology of early Mars and we outline a new model for the nature and evolution of a “cold and icy” Late Noachian climate based on these observations. We conclude that a cold and icy Late Noachian Mars with MAAT below freezing, but peak seasonal and peak daily temperatures above 0°C, could plausibly account for the array of Noachian-aged fluvial and lacustrine features observed on Mars. Our assessment also provides insight into the potential effects of punctuated warming on a cold and icy early Mars, in which impact crater formation or massive volcanic eruptions cause temperatures in the melting range for decadal to centennial timescales. We outline a set of outstanding questions and tests concerning the nature and evolution of these features on Mars.

scholarly journals Glacier mass balances (1993–2001), Taylor Valley, McMurdo Dry Valleys, Antarctica

2006 ◽  
Vol 52 (178) ◽  
pp. 451-462 ◽  
Author(s):  
Andrew G. Fountain ◽  
Thomas H. Nylen ◽  
Karen L. MacClune ◽  
Gayle L. Dana
Keyword(s):  
Mass Balance ◽  
Piecewise Linear ◽  
Objective Assessment ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Mass Balances ◽  
Missing Measurements ◽  
Wind Speeds ◽  
Taylor Valley ◽  
Air Temperatures

AbstractMass balances were measured on four glaciers in Taylor Valley, Antarctica, from 1993 to 2001. We used a piecewise linear regression, which provided an objective assessment of error, to estimate the mass balance with elevation. Missing measurements were estimated from linear regressions between points and showed a significant improvement over other methods. Unlike temperate glaciers the accumulation zone of these polar glaciers accumulates mass in summer and winter and the ablation zone loses mass in both seasons. A strong spatial trend of smaller mass-balance values with distance inland (r2 = 0.80) reflects a climatic gradient to warmer air temperatures, faster wind speeds and less precipitation. Annual and seasonal mass-balance values range only several tens of millimeters in magnitude and no temporal trend is evident. The glaciers of Taylor Valley, and probably the entire McMurdo Dry Valleys, are in equilibrium with the current climate, and contrast with glacier trends elsewhere on the Antarctic Peninsula and in temperate latitudes.

scholarly journals Buried ice in Kennar Valley: a late Pleistocene remnant of Taylor Glacier

2017 ◽  
Vol 29 (3) ◽  
pp. 239-251 ◽  
Author(s):  
Kate M. Swanger
Keyword(s):  
Late Pleistocene ◽  
Ice Cores ◽  
Dry Valleys ◽  
Patterned Ground ◽  
Outlet Glacier ◽  
Air Bubble ◽  
Isotopic Analyses ◽  
Stable Isotopic ◽  
Glacier Ice ◽  
Taylor Glacier

AbstractBuried glacier ice is common in the McMurdo Dry Valleys and under ideal climatic and geomorphological conditions may be preserved for multimillion-year timescales. This study focuses on the analysis of ~300 m2 of buried glacier ice in lower Kennar Valley, Quartermain Range. The mapped ice is clean,<10 m thick and covered by a~25 cm sandy drift. The mouth of Kennar Valley is occupied by a lobe of Taylor Glacier, an outlet glacier from Taylor Dome. Based on ice–sediment characteristics, air bubble concentrations and stable isotopic analyses from three ice cores, the lower Kennar Valley ice is glacial in origin. These data coupled with a previously reported exposure age chronology indicate that the buried ice was deposited by a late Pleistocene advance of Taylor Glacier, probably during an interglacial interval. The surface of the buried glacier ice exhibits a patterned ground morphology characterized by small, dome-shaped polygons with deep troughs. This shape possibly reflects the final stages of ice loss, as stagnant, isolated ice pinnacles sublimate in place. This study highlights how polygon morphology can be used to infer the thickness of clean buried ice and its geomorphological stability throughout Antarctica, as well as other in cold, arid landscapes.

scholarly journals Draft Genome Sequence of Paenisporosarcina sp. Strain TG-14, a Psychrophilic Bacterium Isolated from Sediment-Laden Stratified Basal Ice from Taylor Glacier, McMurdo Dry Valleys, Antarctica

2012 ◽  
Vol 194 (23) ◽  
pp. 6656-6657 ◽  
Author(s):  
Hye Yeon Koh ◽  
Sung Gu Lee ◽  
Jun Hyuck Lee ◽  
Shawn Doyle ◽  
Brent C. Christner ◽  
...  
Keyword(s):  
Genome Sequence ◽  
Draft Genome ◽  
Mcmurdo Dry Valleys ◽  
Draft Genome Sequence ◽  
Psychrophilic Bacterium ◽  
Dry Valleys ◽  
Adaptation Mechanism ◽  
Content Type ◽  
Basal Ice ◽  
Taylor Glacier

ABSTRACTThe psychrophilic bacteriumPaenisporosarcinasp. TG-14 was isolated from sediment-laden stratified basal ice from Taylor Glacier, McMurdo Dry Valleys, Antarctica. Here we report the draft genome sequence of this strain, which may provide useful information on the cold adaptation mechanism in extremely variable environments.

Experimental formation of pore fluids in McMurdo Dry Valleys soils

2014 ◽  
Vol 27 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Joseph Levy ◽  
Andrew Fountain ◽  
W. Berry Lyons ◽  
Kathy Welch
Keyword(s):  
Relative Humidity ◽  
Salt Content ◽  
Soil Samples ◽  
Mcmurdo Dry Valleys ◽  
Absolute Amount ◽  
Dry Valleys ◽  
Pore Waters ◽  
Taylor Valley ◽  
Experimental Formation ◽  
Laboratory Analogue

AbstractThe aim of the study was to determine if soil salt deliquescence and brine hydration can occur under laboratory conditions using natural McMurdo Dry Valleys soils. The experiment was a laboratory analogue for the formation of isolated patches of hypersaline, damp soil, referred to as ‘wet patches’. Soils were oven dried and then hydrated in one of two humidity chambers: one at 100% relative humidity and the second at 75% relative humidity. Soil hydration is highly variable, and over the course of 20 days of hydration, ranged from increases in water content by mass from 0–16% for 122 soil samples from Taylor Valley. The rate and absolute amount of soil hydration correlates well with the soluble salt content of the soils but not with grain size distribution. This suggests that the formation of bulk pore waters in these soils is a consequence of salt deliquescence and hydration of the brine from atmospheric water vapour.

scholarly journals Glaciers in equilibrium, McMurdo Dry Valleys, Antarctica

2016 ◽  
Vol 62 (235) ◽  
pp. 976-989 ◽  
Author(s):  
ANDREW G. FOUNTAIN ◽  
HASSAN J. BASAGIC ◽  
SPENCER NIEBUHR
Keyword(s):  
Mass Balance ◽  
Elevation Gradient ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Equilibrium Line Altitude ◽  
Air Temperatures ◽  
Past Half Century ◽  
Time Of Year ◽  
Snow Storms ◽  
Past Half

ABSTRACTThe McMurdo Dry Valleys are a cold, dry polar desert and the alpine glaciers therein exhibit small annual and seasonal mass balances, often <±0.06 m w.e. Typically, winter is the accumulation season, but significant snow storms can occur any time of year occasionally making summer the accumulation season. The yearly equilibrium line altitude is poorly correlated with mass balance because the elevation gradient of mass balance on each glacier can change dramatically from year to year. Most likely, winds redistribute the light snowfall disrupting the normal gradient of increasing mass balance with elevation. Reconstructed cumulative mass balance shows that the glaciers have lost <2 m w.e. over the past half century and area changes show minimal retreat. In most cases these changes are less than the uncertainty and the glaciers are considered in equilibrium. Since 2000, however, the glaciers have lost mass despite relatively stable summer air temperatures suggesting a different mechanism in play. Whether this trend is a harbinger of future changes or a temporary excursion is unclear.

scholarly journals A Stable Isotopic Investigation of a Polar Desert Hydrologic System, McMurdo Dry Valleys, Antarctica

2006 ◽  
Vol 38 (1) ◽  
pp. 60-71 ◽  
Author(s):  
Michael N. Gooseff ◽  
W. Berry Lyons ◽  
Diane M. McKnight ◽  
Bruce H. Vaughn ◽  
Andrew G. Fountain ◽  
...  
Keyword(s):  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Polar Desert ◽  
Stable Isotopic ◽  
Hydrologic System ◽  
Isotopic Investigation

scholarly journals Evolution of cryoconite holes and their contribution to meltwater runoff from glaciers in the McMurdo Dry Valleys, Antarctica

2004 ◽  
Vol 50 (168) ◽  
pp. 35-45 ◽  
Author(s):  
Andrew G. Fountain ◽  
Martyn Tranter ◽  
Thomas H. Nylen ◽  
Karen J. Lewis ◽  
Derek R. Mueller
Keyword(s):  
Water Levels ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Glacier Surface ◽  
Near Surface ◽  
Ice Melt ◽  
Ice Surface ◽  
Meltwater Runoff ◽  
Hydrologic System ◽  
Chloride Accumulation

AbstractCryoconite holes are water-filled holes in the surface of a glacier caused by enhanced ice melt around trapped sediment. Measurements on the ablation zones of four glaciers in Taylor Valley, Antarctica, show that cryoconite holes cover about 4–6% of the ice surface. They typically vary in diameter from 5 to 145 cm, with depths ranging from 4 to 56 cm. In some cases, huge holes form with 5 m depths and 30 m diameters. Unlike cryoconite holes elsewhere, these have ice lids up to 36 cm thick and melt from within each spring. About one-half of the holes are connected to the near-surface hydrologic system and the remainder are isolated. The duration of isolation, estimated from the chloride accumulation in hole waters, commonly shows ages of several years, with one hole of 10 years. The cryoconite holes in the McMurdo Dry Valleys create a near-surface hydrologic system tens of cm below the ice surface. The glacier surface itself is generally frozen and dry. Comparison of water levels between holes a few meters apart shows independent cycles of water storage and release. Most likely, local freeze–thaw effects control water passage and therefore temporary storage. Rough calculations indicate that the holes generate at least 13% of the observed runoff on the one glacier measured. This hydrologic system represents the transition between a melting ice cover with supraglacial streams and one entirely frozen and absent of water.

scholarly journals The origin of channels on lower Taylor Glacier, McMurdo Dry Valleys, Antarctica, and their implication for water runoff

2005 ◽  
Vol 40 ◽  
pp. 1-7 ◽  
Author(s):  
Robin R. Johnston ◽  
Andrew G. Fountain ◽  
Thomas H. Nylen
Keyword(s):  
Energy Balance ◽  
Water Discharge ◽  
Mcmurdo Dry Valleys ◽  
Equilibrium Geometry ◽  
Water Runoff ◽  
Dry Valleys ◽  
Glacier Surface ◽  
Field Evidence ◽  
Developed Surface ◽  
Taylor Glacier

AbstractWell-developed surface channels on Taylor Glacier, McMurdo Dry Valleys, Antarctica, begin as medial moraines incised as shallow, narrow surface depressions, and retain this geometry for tens of km. Over a distance of 1100 m, the channel geometry dramatically changes, reaching depths >20m and widths >100 m. After rapidly enlarging, the channels appear to evolve toward a new equilibrium geometry. Compared to the glacier surface, the air temperature in the channels is warmer by ∼1.7˚C, wind speed is reduced by ∼2.4ms–1 and net shortwave radiation is greater by ∼14Wm–2. The microclimate in the channel shifts the energy balance towards enhanced melt. Field evidence and energy-balance modeling indicate ablation in the deep channels is ∼4.5 times greater than the local horizontal glacier surface and that melt accounts for ∼99% of the summer ablation, compared to ∼75% on the adjacent horizontal glacier surface. Melt in these channels supplies 65% of the unaccounted water discharge into the neighboring lake. In large part, the channels generate the water they carry, rather than merely route water generated elsewhere.

Spatial variations in the geochemistry of glacial meltwater streams in the Taylor Valley, Antarctica

2010 ◽  
Vol 22 (6) ◽  
pp. 662-672 ◽  
Author(s):  
Kathleen A. Welch ◽  
W. Berry Lyons ◽  
Carla Whisner ◽  
Christopher B. Gardner ◽  
Michael N. Gooseff ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Freezing Point ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Stream Chemistry ◽  
Glacial Meltwater ◽  
Taylor Valley ◽  
Air Temperatures ◽  
Wide Range ◽  
Long Term Ecological Research

AbstractStreams in the McMurdo Dry Valleys, Antarctica, flow during the summer melt season (4–12 weeks) when air temperatures are close to the freezing point of water. Because of the low precipitation rates, streams originate from glacial meltwater and flow to closed-basin lakes on the valley floor. Water samples have been collected from the streams in the Dry Valleys since the start of the McMurdo Dry Valleys Long-Term Ecological Research project in 1993 and these have been analysed for ions and nutrient chemistry. Controls such as landscape position, morphology of the channels, and biotic and abiotic processes are thought to influence the stream chemistry. Sea-salt derived ions tend to be higher in streams that are closer to the ocean and those streams that drain the Taylor Glacier in western Taylor Valley. Chemical weathering is an important process influencing stream chemistry throughout the Dry Valleys. Nutrient availability is dependent on landscape age and varies with distance from the coast. The streams in Taylor Valley span a wide range in composition and total dissolved solids and are surprisingly similar to a wide range of much larger temperate and tropical river systems.

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