Rock glacier characteristics serve as an indirect record of multiple alpine glacier advances in Taylor Valley, Antarctica

Abstract. The geomorphic record indicates that alpine glaciers in the McMurdo Dry Valleys of southern Victoria Land, Antarctica, appear to advance during interglacial periods in response to ice-free conditions in the Ross Sea. Few records of these advances are preserved and/or subaerially exposed, complicating the interpretations of regional glacier response to climate changes. Here, we present geophysical and geochemical analyses of a rock glacier that originates from icefalls fed by alpine Doran Glacier in central Taylor Valley. The rock glacier exhibits a trend of increased weathering of granitic clasts via ventifaction and grussification down-flow. Meltwater ponds on the rock glacier exhibit variable salinity that ranges from freshwater to higher than seawater, with the highest salinity pond near the rock glacier toe. Ground-penetrating radar analyses reveal the feature to possess a primarily clean ice interior, with layers of englacial debris. Stable isotopic data from three ice cores support a glacial origin for the ice within the rock glacier. These data suggest that the current morphology of the rock glacier is the result of multiple events of increased ice contribution caused by advances of Doran Glacier, which is the main source of ice to the rock glacier. We therefore demonstrate the potential of ice-cored rock glaciers to record multiple advances and retreats of Dry Valley glaciers, permitting the interpretation of glacial responses to Pleistocene and Holocene climate change even where direct records are not present.

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Rock glacier characteristics serve as an indirect record of multiple alpine glacier advances in Taylor Valley, Antarctica

10.5194/tc-2019-135 ◽

2019 ◽

Author(s):

Kelsey Winsor ◽

Kate M. Swanger ◽

Esther Babcock ◽

Rachel D. Valletta ◽

James L. Dickson

Keyword(s):

Ross Sea ◽

Ice Cores ◽

Dry Valleys ◽

Rock Glacier ◽

Alpine Glacier ◽

Glacial Origin ◽

Taylor Valley ◽

Dry Valley ◽

Geochemical Analyses ◽

Ground Penetrating

Abstract. The geomorphic record indicates that alpine glaciers in the McMurdo Dry Valleys of southern Victoria Land, Antarctica appear to advance during interglacial periods in response to ice-free conditions in the Ross Sea. Few records of these advances are preserved and/or subaerially exposed, complicating the interpretations of regional glacier response to climate changes. Here, we present geophysical and geochemical analyses of a rock glacier that originates from icefalls fed by alpine Doran Glacier in central Taylor Valley. The rock glacier exhibits a trend of increased weathering of granitic clasts via ventifaction and grussification down-flow. Meltwater ponds on the rock glacier exhibit variable salinity that ranges from freshwater to higher than seawater, with the highest salinity pond near the rock glacier toe. Ground-penetrating radar analyses reveal the feature to possess a primarily clean ice interior, with layers of englacial debris. Stable isotopic data from three ice cores support a glacial origin for the ice within the rock glacier. These data suggest that the current morphology of the rock glacier is the result of multiple events of increased ice contribution caused by advances of Doran Glacier, which is the main source of the ice that cores the rock glacier. We therefore demonstrate the potential of ice-cored rock glaciers to record multiple advances and retreats of Dry Valley glaciers, permitting the interpretation of glacial responses to Pleistocene and Holocene climate change even where direct records are not present.

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Influence of Late Holocene climate on Lake Eggers hydrology, McMurdo Sound

Antarctic Science ◽

10.1017/s0954102021000018 ◽

2021 ◽

pp. 1-13

Author(s):

E.J. Chamberlain ◽

A.J. Christ ◽

R.W. Fulweiler

Keyword(s):

Late Holocene ◽

Ross Sea ◽

Regional Climate ◽

Ice Cores ◽

Lake Ice ◽

Mcmurdo Sound ◽

Ice Accumulation ◽

History Of ◽

Ground Penetrating ◽

Western Ross Sea

Abstract Ice-covered lakes in Antarctica preserve records of regional hydroclimate and harbour extreme ecosystems that may serve as terrestrial analogues for exobiotic environments. Here, we examine the impacts of hydroclimate and landscape on the formation history of Lake Eggers, a small ice-sealed lake, located in the coastal polar desert of McMurdo Sound, Antarctica (78°S). Using ground penetrating radar surveys and three lake ice cores we characterize the ice morphology and chemistry. Lake ice geochemistry indicates that Lake Eggers is fed primarily from local snowmelt that accreted onto the lake surface during runoff events. Radiocarbon ages of ice-encased algae suggest basal ice formed at least 735 ± 20 calibrated years before present (1215 C.E.). Persisting through the Late Holocene, Lake Eggers alternated between periods of ice accumulation and sublimation driven by regional climate variability in the western Ross Sea. For example, particulate organic matter displayed varying δ15N ratios with depth, corresponding to sea ice fluctuations in the western Ross Sea during the Late Holocene. These results suggest a strong climatic control on the hydrologic regime shifts shaping ice formation at Lake Eggers.

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Physical properties of shallow ice cores from Antarctic and sub-Antarctic islands

The Cryosphere ◽

10.5194/tc-15-1173-2021 ◽

2021 ◽

Vol 15 (2) ◽

pp. 1173-1186

Author(s):

Elizabeth Ruth Thomas ◽

Guisella Gacitúa ◽

Joel B. Pedro ◽

Amy Constance Faith King ◽

Bradley Markle ◽

...

Keyword(s):

Ground Penetrating Radar ◽

Ross Sea ◽

Ice Core ◽

Ice Cores ◽

Atmospheric Temperature ◽

Peter 1 ◽

Density Profiles ◽

Minimal Impact ◽

Bellingshausen Sea ◽

Ground Penetrating

Abstract. The sub-Antarctic is one of the most data-sparse regions on earth. A number of glaciated Antarctic and sub-Antarctic islands have the potential to provide unique ice core records of past climate, atmospheric circulation, and sea ice. However, very little is known about the glaciology of these remote islands or their vulnerability to warming atmospheric temperature. Here we present melt histories and density profiles from shallow ice (firn) cores (14 to 24 m) drilled on three sub-Antarctic islands and two Antarctic coastal domes. Additionally, complementary ground-penetrating radar (GPR) data were collected to further characterize each site and assess the spatial distribution of the observed melt layers. This study includes the first ever firn cores from Bouvet Island (54∘25′19′′ S, 03∘23′27′′ E) in the South Atlantic, from Peter I Island (68∘51′05′′ S, 90∘30′35′′ W) in the Bellingshausen Sea, and from Young Island (66∘31′44′′ S, 162∘33′21′′ E) in the Ross Sea sector's Balleny island chain. Despite their sub-Antarctic location, surface melt is low at most sites (melt layers account for ∼ 10 % of total core), with undisturbed ice layers in the upper ∼ 40 m, suggesting minimal impact of meltwater percolation. The exception is Young Island, where melt layers account for 47 % of the firn core. Surface snow densities range from 0.47 to 0.52 kg m−3, with close-off depths ranging from 21 to 51 m. Based on the measured density, we estimate that the bottom ages of a 100 m ice core drilled on Peter 1 Island would reach ∼ 1856 CE and ∼ 1874 CE at Young Island.

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Viable microbes in ice: application of molecular assays to McMurdo Dry Valley lake ice communities

Antarctic Science ◽

10.1017/s0954102010000404 ◽

2010 ◽

Vol 22 (5) ◽

pp. 470-476 ◽

Cited By ~ 7

Author(s):

Markus Dieser ◽

Andreas Nocker ◽

John C. Priscu ◽

Christine M. Foreman

Keyword(s):

Denaturing Gradient Gel Electrophoresis ◽

Extreme Environments ◽

Membrane Integrity ◽

Pcr Amplification ◽

Ice Cores ◽

16S Rrna Genes ◽

Rrna Genes ◽

Dry Valleys ◽

Dry Valley ◽

Gradient Gel Electrophoresis

AbstractThe permanent ice covers of the McMurdo Dry Valley lakes, Antarctica, are colonized by a diverse microbial assemblage. We collected ice cores from Lakes Fryxell, Hoare and Bonney. Propidium monoazide (PMA) was used in combination with quantitative PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE) to examine membrane integrity of prokaryotes in these extreme environments. PMA selectively penetrates cells with compromised membranes and modifies their DNA resulting in the suppression of PCR amplification. Our results based on analysis of 16S rRNA genes demonstrate that despite the hostile conditions of the Dry Valleys, the permanent ice covers of the lakes support a ‘potentially viable’ microbial community. The level of membrane integrity, as well as diversity, was higher in samples where sediment was entrapped in the ice cover. Pronounced differences in the fraction of cells with intact and compromised cell membranes were found for Lake Fryxell and east lobe of Lake Bonney, both expressed in differences in DGGE banding patterns and qPCR signal reductions. Limitations in the ability to distinguish between intact or compromised cells occurred in samples from Lake Hoare and west lobe of Lake Bonney due to low DNA template concentrations recovered from the samples.

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Physical properties of shallow ice cores from Antarctic and sub-Antarctic islands

10.5194/tc-2020-110 ◽

2020 ◽

Author(s):

Elizabeth Ruth Thomas ◽

Guisella Gacitúa ◽

Joel B. Pedro ◽

Amy Constance Faith King ◽

Bradley Markle ◽

...

Keyword(s):

Ground Penetrating Radar ◽

Ross Sea ◽

Ice Core ◽

Ice Cores ◽

Density Profiles ◽

Minimal Impact ◽

Bellingshausen Sea ◽

Water Percolation ◽

Remote Islands ◽

Ground Penetrating

Abstract. The sub-Antarctic is one of the most data sparse regions on earth. A number of glaciated Antarctic and sub-Antarctic islands have the potential to provide unique ice core records of past climate, atmospheric circulation and sea ice. However, very little is known about the glaciology of these remote islands or their vulnerability to warming atmospheric temperatures. Here we present ground penetrating radar (GPR), melt histories and density profiles from shallow ice cores (14 to 24 m) drilled on three sub-Antarctic islands and two Antarctic coastal domes. This includes the first ever ice cores from Bouvet Island (54°26’0 S, 3°25’0 E) in the South Atlantic, from Peter 1st Island (68°50’0 S, 90°35’0 W) in the Bellingshausen Sea and from Young Island (66°17′ S, 162°25′ E) in the Ross Sea sector’s Balleny Islands chain. Despite their sub-Antarctic location, surface melt is low at most sites (melt layers account for ∼10 % of total core), with undisturbed ice layers in the upper ∼40 m, suggesting minimal impact of melt water percolation. The exception is Young Island, where melt layers account for 47 % of the ice core. Surface snow densities range from 0.47 to 0.52 kg m3, with close-off depths ranging from 21 to 51 m. Based on the measured density, we estimate that the bottom ages of a 100 m ice core drilled on Peter 1st Island would reach ~1836 AD and ~1743 AD at Young Island.

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Origin, structure and geochemistry of a rock glacier near Don Juan Pond, Wright Valley, Antarctica

Antarctic Science ◽

10.1017/s0954102020000139 ◽

2020 ◽

Vol 32 (4) ◽

pp. 273-287

Author(s):

Kelsey Winsor ◽

Kate M. Swanger ◽

Esther L. Babcock ◽

James L. Dickson ◽

Rachel D. Valletta ◽

...

Keyword(s):

Late Quaternary ◽

Feedback System ◽

Dry Valleys ◽

Don Juan ◽

Soil Leaching ◽

X Ray Diffraction ◽

South Fork ◽

Rock Glacier ◽

Rock Glaciers ◽

Ground Penetrating

AbstractThe South Fork of Wright Valley contains one of the largest rock glaciers in the McMurdo Dry Valleys, Antarctica, stretching 7 km from the eastern boundary of the Labyrinth and terminating at Don Juan Pond (DJP). Here, we use results from ground-penetrating radar (GPR), qualitative field observations, soil leaching analyses and X-ray diffraction analyses to investigate rock glacier development. The absence of significant clean ice in GPR data, paired with observations of talus and interstitial ice influx from the valley walls, support rock glacier formation via talus accumulation. A quartz-dominated subsurface composition and discontinuous, well-developed desert pavements suggest initial rock glacier formation occurred before the late Quaternary. Major ion data from soil leaching analyses show higher salt concentrations in the rock glacier and talus samples that are close to hypersaline DJP. These observations suggest that DJP acts as a local salt source to the rock glacier, as well as the surrounding talus slopes that host water track systems that deliver solutes back into the lake, suggesting a local feedback system. Finally, the lack of lacustrine sedimentation on the rock glacier is inconsistent with the advance of a glacially dammed lake into South Fork during the Last Glacial Maximum.

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The seasonal evolution of albedo across glaciers and the surrounding landscape of the Taylor Valley, Antarctica

10.5194/tc-2019-146 ◽

2019 ◽

Cited By ~ 1

Author(s):

Anna Bergstrom ◽

Michael Gooseff ◽

Madeline Myers ◽

Peter T. Doran

Keyword(s):

Austral Summer ◽

Short Wave ◽

Desert Ecosystem ◽

Dry Valleys ◽

Seasonal Evolution ◽

Taylor Valley ◽

Incoming Radiation ◽

Dry Valley ◽

Summer Temperatures ◽

Surrounding Landscape

Abstract. The McMurdo Dry Valleys (MDVs) of Antarctica are a polar desert ecosystem consisting of alpine glaciers, ice-covered lakes, streams, and expanses of vegetation-free rocky soil. Because average summer temperatures are close to 0 °C, glacier melt dynamics in particular, but the Dry Valley ecosystem in general, are closely linked to the energy balance. A slight increase in incoming radiation or change in albedo can have large effects on the timing and volume of melt water. However, we have yet to fully characterize the seasonal evolution or spatial variability of albedo in the valleys. In this study, we aim to understand the drivers of landscape albedo change within and across seasons. To do so, we used a camera, gps, and short wave radiometer from a helicopter-based platform to fly transects 4–5 times a season along Taylor Valley over three seasons. We coupled these data with incoming radiation measured at 6 meteorological stations distributed along the valley to calculate the distribution of albedo across individual glaciers, lakes, and the soil surfaces. We hypothesized that albedo would decrease throughout the austral summer with ablation of snow patches and ice and increasing sediment exposure on the glacier and lake surfaces. However, small snow events (

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