Shallow seismic surveys and ice thickness estimates of the Mullins Valley debris-covered glacier, McMurdo Dry Valleys, Antarctica

2007 ◽  
Vol 19 (4) ◽  
pp. 485-496 ◽  
Author(s):  
David E. Shean ◽  
James W. Head ◽  
David R. Marchant
Keyword(s):  
Mcmurdo Dry Valleys ◽  
P Wave ◽  
Ice Thickness ◽  
Dry Valleys ◽  
Near Surface ◽  
Seismic Surveys ◽  
Shallow Seismic ◽  
Ice Accumulation ◽  
Active Portion ◽  
Glacier Ice

AbstractSeveral debris-covered glaciers occupy tributaries of upper Beacon Valley, Antarctica. Understanding their flow dynamics and ice thickness is important for palaeoclimate studies and for understanding the origins of ancient ice elsewhere in the McMurdo Dry Valleys region. We present the results of several shallow seismic surveys in Mullins Valley, where the largest of these debris-covered glaciers is located. Our results suggest that beneath a thin sublimation till and near-surface horizon of dirty glacier ice, lies relatively pure glacier ice (P-wave velocity ~3700–3800 m s-1), with total thickness estimates of ~90–95 m towards the valley head, and ~40–65 m near the entrance to Beacon Valley, ~2.5 km downglacier. P-wave velocities decrease downvalley, suggesting that the material properties of the ice change with increasing distance from the ice-accumulation zone. These new data are used to calibrate an ice thickness profile for the active portion of the Mullins Valley debris-covered glacier (upper ~3.5 km) and to shed light on the origin and spatial distribution of enclosed debris.

scholarly journals Seismic and GPR surveys of Mullins Glacier, McMurdo Dry Valleys, Antarctica: ice thickness, internal structure and implications for surface ridge formation

2010 ◽  
Vol 56 (195) ◽  
pp. 48-64 ◽  
Author(s):  
David E. Shean ◽  
David R. Marchant
Keyword(s):  
Environmental Changes ◽  
Ground Surface ◽  
Ice Thickness ◽  
Formation Mechanisms ◽  
Dry Valleys ◽  
Glacier Surface ◽  
Seismic Surveys ◽  
Ice Accumulation ◽  
Paleoclimate Records ◽  
Ground Penetrating

AbstractWe present results from ground-penetrating radar (GPR) and seismic surveys for the Mullins Valley debris-covered glacier (Mullins Glacier), Antarctica, that yield local ice-thickness estimates of 80–110 m in upper Mullins Valley and 150 m in upper Beacon Valley. Englacial debris in upper Mullins Glacier occurs as scattered cobbles and as discrete layers. One extensive englacial debris layer, which appears as a coherent reflector dipping 40–45° up-valley, intersects the ground surface within an ∼8 m high ice-cored ridge, the largest of several ridges that mark the glacier surface. Field excavations reveal that this englacial interface consists of multiple debris bands that can be directly correlated with ridge microtopography. Englacial debris layers most probably originate as concentrated rockfall in ice accumulation zones and/or as surface lags that form as dirty ice sublimes during periods of negative mass balance. A similar pattern of surface ridges on Friedman Glacier (∼2.5 km west of Mullins Glacier) suggests regional environmental changes are involved in ridge formation. These observations carry implications for evaluating debris entrainment and surface ridge formation mechanisms in cold-based, debris-covered glaciers and provide a glaciological framework for evaluating and interpreting paleoclimate records from Mullins Glacier.

scholarly journals Cryoconite hole connectivity on the Wright Lower Glacier, McMurdo Dry Valleys, Antarctica

2016 ◽  
Vol 62 (234) ◽  
pp. 714-724 ◽  
Author(s):  
SHELLEY MACDONELL ◽  
MARTIN SHARP ◽  
SEAN FITZSIMONS
Keyword(s):  
Spatial Variability ◽  
Drainage System ◽  
Chloride Content ◽  
Mcmurdo Dry Valleys ◽  
Hydrological Connectivity ◽  
Dry Valleys ◽  
Near Surface ◽  
Cryoconite Hole ◽  
Transfer Method ◽  
Surface Ice

ABSTRACTCryoconite holes can be important sources and stores of water and nutrients on cold and polythermal glaciers, and they provide a habitat for various forms of biota. Understanding the hydrological connectivity of cryoconite holes may be the key to understanding the transport of nutrients and biological material to the proglacial areas of such glaciers. This paper aims to characterize and explain spatial variability in the connectivity of ice-lidded cryoconite holes on a small, piedmont glacier in the McMurdo Dry Valleys through geochemical analysis of cryoconite hole waters. Solute concentrations in both surface and near-surface ice and cryoconite holes, vary greatly along the glacier centerline, and all sample types displayed similar spatial patterns of variability. Using chloride as a tracer, we estimated variations in cryoconite hole connectivity along the glacier centerline. We found that a previously used mass transfer method did not provide reliable estimates of the time period for which cryoconite hole waters had been isolated from the atmosphere. We attribute this to spatial variability in both the chloride content of the surface ice and surface ablation rates. The approach may, however, be used to qualitatively characterize spatial variations in the hydrological connectivity of the cryoconite holes. These results also suggest that ice-lidded cryoconite holes are never truly isolated from the near-surface drainage system.

scholarly journals Near‐Surface Refractory Black Carbon Observations in the Atmosphere and Snow in the McMurdo Dry Valleys, Antarctica, and Potential Impacts of Foehn Winds

2018 ◽  
Vol 123 (5) ◽  
pp. 2877-2887 ◽  
Author(s):  
Alia L. Khan ◽  
Gavin R. McMeeking ◽  
Joshua P. Schwarz ◽  
Peng Xian ◽  
Kathleen A. Welch ◽  
...  
Keyword(s):  
Black Carbon ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Near Surface

Distribution and origin of ground ice in University Valley, McMurdo Dry Valleys, Antarctica

2016 ◽  
Vol 29 (2) ◽  
pp. 183-198 ◽  
Author(s):  
Caitlin Lapalme ◽  
Denis Lacelle ◽  
Wayne Pollard ◽  
David Fisher ◽  
Alfonso Davila ◽  
...  
Keyword(s):  
Vapour Deposition ◽  
Ground Surface ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Ground Ice ◽  
Permafrost Soils ◽  
Glacier Ice ◽  
Ice Conditions ◽  
Ice Content ◽  
Moisture Conditions

AbstractGround ice is one of the most important and dynamic geologic components of permafrost; however, few studies have investigated the distribution and origin of ground ice in the McMurdo Dry Valleys of Antarctica. In this study, ice-bearing permafrost cores were collected from 18 sites in University Valley, a small hanging glacial valley in the Quartermain Mountains. Ground ice was found to be ubiquitous in the upper 2 m of permafrost soils, with excess ice contents reaching 93%, but ground ice conditions were not homogeneous. Ground ice content was variable within polygons and along the valley floor, decreasing in the centres of polygons and increasing in the shoulders of polygons towards the mouth of the valley. Ground ice also had different origins: vapour deposition, freezing of partially evaporated snow meltwater and buried glacier ice. The variability in the distribution and origin of ground ice can be attributed to ground surface temperature and moisture conditions, which separate the valley into distinct zones. Ground ice of vapour-deposition origin was predominantly situated in perennially cryotic zones, whereas ground ice formed by the freezing of evaporated snow meltwater was predominantly found in seasonally non-cryotic zones.

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 Meteorological Connectivity from Regions of High Biodiversity within the McMurdo Dry Valleys of Antarctica

2019 ◽  
Vol 58 (11) ◽  
pp. 2437-2452
Author(s):  
M. Katurji ◽  
B. Khan ◽  
M. Sprenger ◽  
R. Datta ◽  
K. Joy ◽  
...  
Keyword(s):  
Surface Wind ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Aeolian Transport ◽  
Near Surface ◽  
Weather Patterns ◽  
Synoptic Weather ◽  
Weather Model ◽  
Topographic Forcing

AbstractMeteorological connectivity between biological hot spots of the McMurdo Dry Valleys (MDVs) of Antarctica is thought to play a role in species distribution and abundance through the aeolian transport of bioaerosols. Understanding the potential role of such meteorological connectivity requires an understanding of near-surface wind flow within and between valley airsheds. To address this, we applied Lagrangian wind trajectory modeling to mesoscale (spatial resolution of ~1 km) weather model output to predict connectivity pathways, focusing on regions of high biodiversity. Our models produce maps of a likelihood metric of wind connectivity that demonstrate the synoptic and mesoscale dependence of connections between local, near-local, and nonlocal areas on wind transport, modulated by synoptic weather and topographic forcing. These connectivity areas can have spatial trends modulated by the synoptic weather patterns and locally induced topographically forced winds. This method is transferrable to other regions of Antarctica for broader terrestrial, coastal, and offshore ecological connectivity research. Also, our analysis and methods can inform better placement of aeolian dust and bioaerosol samplers in the McMurdo Dry Valleys, provide preliminary guidelines behind the meteorological controls of sediment transport and smaller particle distribution, and present quantifiable knowledge informing new hypotheses around the potential of wind acting as a physical driver for biological connectivity in the MDVs.

High-resolution ground-penetrating radar profiles of perennial lake ice in the McMurdo Dry Valleys, Antarctica: Horizon attributes, unconformities, and subbottom penetration

Geophysics ◽  
2016 ◽  
Vol 81 (1) ◽  
pp. WA13-WA20 ◽  
Author(s):  
Hilary A. Dugan ◽  
Steven A. Arcone ◽  
Maciej K. Obryk ◽  
Peter T. Doran
Keyword(s):  
Ground Penetrating Radar ◽  
Surface Runoff ◽  
Bottom Topography ◽  
Mcmurdo Dry Valleys ◽  
Ice Thickness ◽  
General Interest ◽  
Dry Valleys ◽  
Lake Ice ◽  
Surrounding Matrix ◽  
Ground Penetrating

Ground-penetrating radar (GPR) is not commonly used to study lake ice, and in general, the ground-based use of radar frequencies greater than 500 MHz in cryosphere geophysics is rare, due to a general interest in deeper stratigraphy and the difficulty of extensive profiling over rough snow surfaces. Our goal was to find further information on the origin of the deposition and formation of intra-ice layers, bottom topography, and subbottom deposits using GPR with pulses centered near 850 MHz on two permanently ice-covered lakes in the McMurdo Dry Valleys, Antarctica. The profiles were obtained using a one-person sled operation over Lake Bonney, which is typical of lakes in the region, having an ice thickness that ranges between 3 and 5 m, and Lake Vida, where the maximum ice depth is at least 27 m. Lake Bonney exhibits a semicontinuous sediment horizon at approximately a 2-m depth and several minor horizons. In contrast, Lake Vida contains unconformably eroded and folded continuous reflection horizons, packages of minor horizons between major horizons, evidence of incised fluvial deposition along the bottom, and subbottom penetration of at least 4.5 m in some areas. Where the ice thickness is less than 20 m, the lake is frozen to the bottom. Most horizon waveform phase attributes indicate relatively lower permittivity than in the surrounding matrix. Consequently, we interpreted these strata to be caused by layers of pure ice embedded within a salty and dirty ice matrix, which were formed during minor flooding. These findings supported previous conclusions that Lake Vida ice formed from surface runoff in combination with periods of ablation.

Cryostratigraphy of mid-Miocene permafrost at Friis Hills, McMurdo Dry Valleys of Antarctica

2020 ◽  
pp. 1-15
Author(s):  
Marjolaine Verret ◽  
Warren Dickinson ◽  
Denis Lacelle ◽  
David Fisher ◽  
Kevin Norton ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Meteoric Water ◽  
Arid Environment ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Ground Ice ◽  
Near Surface ◽  
Air Temperatures ◽  
Drilling Project

Abstract The origin and stability of ground ice in the stable uplands of the McMurdo Dry Valleys remains poorly understood, with most studies focusing on the near-surface permafrost. The 2016 Friis Hills Drilling Project retrieved five cores reaching 50 m depth in mid-Miocene permafrost, a period when Antarctica transitioned to a hyper-arid environment. This study characterizes the cryostratigraphy of arguably the oldest permafrost on Earth and assesses 15 Myr of ground ice evolution using the REGO model. Four cryostratigraphic units were identified: 1) surficial dry permafrost (0–30 cm), 2) ice-rich to ice-poor permafrost (0.3–5.0 m) with high solute load and δ18O values (-16.2 ± 1.8‰) and low D-excess values (-65.6 ± 4.3‰), 3) near-dry permafrost (5–20 m) and 4) ice-poor to ice-rich permafrost (20–50 m) containing ice lenses with low solute load and δ18O values (-34.6 ± 1.2‰) and D-excess of 6.9 ± 2.6‰. The near-surface δ18O profile of ground ice is comparable to other sites in the stable uplands, suggesting that this ice is actively responding to changing surface environmental conditions and challenging the assumption that the surface has remained frozen for 13.8 Myr. The deep ice lenses probably originate from the freezing of meteoric water during the mid-Miocene, and their δ18O composition suggests mean annual air temperatures ~7–11°C warmer than today.

THE IMPACT OF CLIMATE CHANGE ON LAKE VANDA, MCMURDO DRY VALLEYS, ANTARCTICA

2016 ◽  
Author(s):  
Devin Castendyk ◽  
◽  
Maciej K. Obryk ◽  
Sasha Z. Leidman ◽  
Michael Gooseff ◽  
...  
Keyword(s):  
Climate Change ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Impact Of Climate Change ◽  
The Impact
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