USING STREAMLINED LANDFORMS TO RECONSTRUCT AND COMPARE PALEO-ICE FLOW PATHS IN NORTH ICELAND AND NORTHWESTERN PENNSYLVANIA

AbstractCores acquired from the Ross Sea continental shelf and continental slope during the XXX Italian Programma Nazionale di Ricerche in Antartide (PNRA) were analysed and yielded interesting micropalaeontological, biostratigraphic diatom results and palaeoceanographic implications. These multi-proxy analyses enabled us to reconstruct the glacial/deglacial history of this sector of the Ross embayment over the last 40 000 years, advancing our understanding of the Last Glacial Maximum (LGM) environmental and sedimentological processes linked to the Ross Sea ice sheet/ice shelf fluctuations in a basin and continental-slope environment, and allowed us to measure some of the palaeoceanographic dynamics. The central sector of the Ross Sea and part of its coast (south of the Drygalski Ice Tongue) enjoyed open marine conditions in the pre-LGM era (27 500–24 000 years bp). The retreat of the ice sheet could have been influenced by a southward shift of a branch of the Ross gyre, which triggered early deglaciation at c. 18 600 cal bp with a significant Modified Circumpolar Deep Water inflow over the continental slope at c. 14 380 cal BP. We assume that a lack of depositional material in each core, although at different times, represents a hiatus. Other than problems in core collection, this could be due to the onset of modern oceanographic conditions, with strong gravity currents and strong High Salinity Shelf Water exportation. Moreover, we presume that improvements in biostratigraphy, study of reworked diatom taxa, and lithological and geochemical analyses will provide important constraints for the reconstruction of the LGM grounding line, ice-flow lines and ice-flow paths and an interesting tool for reconstructing palaeo-sub-bottom currents in this sector of the Ross embayment.

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Configuration of the Northern Antarctic Peninsula Ice Sheet at LGM based on a new synthesis of seabed imagery

The Cryosphere ◽

10.5194/tc-9-613-2015 ◽

2015 ◽

Vol 9 (2) ◽

pp. 613-629 ◽

Cited By ~ 23

Author(s):

C. Lavoie ◽

E. W. Domack ◽

E. C. Pettit ◽

T. A. Scambos ◽

R. D. Larter ◽

...

Keyword(s):

Continental Shelf ◽

Antarctic Peninsula ◽

Flow Direction ◽

Time Interval ◽

Data Sets ◽

Flow Paths ◽

Ice Flow ◽

New Synthesis ◽

National Programs ◽

Streaming Flow

Abstract. We present a new seafloor map for the northern Antarctic Peninsula (AP), including swath multibeam data sets from five national programs. Our map allows for the examination and interpretation of Last Glacial Maximum (LGM) paleo-ice-flow paths developed on the seafloor from the preservation of mega-scale glacial lineations, drumlinized features, and selective linear erosion. We combine this with terrestrial observations of flow direction to place constraints on ice divides and ice domes on the AP continental shelf during the LGM time interval. The results show a flow bifurcation as ice exits the Larsen B embayment. Flow emanating off the Seal Nunataks (including Robertson Island) is directed toward the southeast, then eastward as the flow transits toward the Robertson Trough. A second, stronger "streaming flow" is directed toward the southeast, then southward as ice overflowed the tip of the Jason Peninsula to reach the southern perimeter of the embayment. Our reconstruction also refines the extent of at least five other distinct paleo-ice-stream systems that, in turn, serve to delineate seven broad regions where contemporaneous ice domes must have been centered on the continental shelf at LGM. Our reconstruction is more detailed than other recent compilations because we followed specific ice-flow indicators and have kept tributary flow paths parallel.

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Sediment, glaciohydraulic supercooling, and fast glacier flow

Annals of Glaciology ◽

10.3189/172756403781816121 ◽

2003 ◽

Vol 36 ◽

pp. 135-141 ◽

Cited By ~ 20

Author(s):

Richard B. Alley ◽

Daniel E. Lawson ◽

Edward B. Evenson ◽

Grahame J. Larson

Keyword(s):

Simple Model ◽

Hypothesis Testing ◽

Surface Slope ◽

Sediment Thickness ◽

Flow Paths ◽

Ice Flow ◽

Common Features ◽

Model Based ◽

Glacier Flow

AbstractGlaciers often advance over proglacial sediments, which then may enhance basal motion. For glaciers with abundant meltwater, thermodynamic considerations indicate that the sediment–ice contact in the direction of ice flow tends toward an angle opposed to and somewhat steeper than the surface slope (by slightly more than 50%). A simple model based on this hypothesis yields the extent of over-ridden sediments as a function of sediment thickness and strength, a result that may be useful in guiding additional fieldwork for hypothesis testing. Sediment-floored as well as rock-floored overdeepenings are common features along glacier flow paths and are expected based on theories of glacier erosion, entrainment, transport and deposition.

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Contemporaneous, localized, basal ice-flow variations: implications for bedrock erosion and the origin of p-forms

Journal of Glaciology ◽

10.3189/172756500781833197 ◽

2000 ◽

Vol 46 (154) ◽

pp. 470-476 ◽

Cited By ~ 16

Author(s):

Brice R. Rea ◽

David J. A. Evans ◽

Tom S. Dixon ◽

W. Brian Whalley

Keyword(s):

Flow Direction ◽

Flow Patterns ◽

Stress Regime ◽

Flow Paths ◽

Ice Flow ◽

Mechanical Abrasion ◽

Bedrock Topography ◽

Basal Ice ◽

Bedrock Erosion ◽

Bed Roughness

AbstractA detailed study of a proglacial bedrock site and a subglacial cavity of an outlet of Øksfjordjøkelen, Norway, is presented together with observations from the foreland of Konowbreen, Spitsbergen. Striation directions and subglacial observations indicate that local ice-flow paths were highly variable, deviating at angles of approximately 90° from the main ice-flow direction. Stepped bedrock topography appears conducive to the production of highly variable ice-flow paths, because the high bed roughness creates a locally variable stress regime within the ice, including low-pressure, lee-side areas into which ice can flow. If ice flow is sustained along a specific path and the ice contains debris, then abrasion should produce an erosional bedform. Models are proposed whereby locally variable ice-flow patterns could produce erosional bedforms, which would be described as p-forms, purely through mechanical abrasion.

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Optimal ferromagnetic fraction in till samples along ice-flow paths: case studies from the Sue-Dianne and Thompson deposits, Canada

Geochemistry Exploration Environment Analysis ◽

10.1144/geochem2013-212 ◽

2014 ◽

Vol 14 (4) ◽

pp. 315-329 ◽

Cited By ~ 8

Author(s):

A.-A. Sappin ◽

C. Dupuis ◽

G. Beaudoin ◽

M. Pozza ◽

I. McMartin ◽

...

Keyword(s):

Case Studies ◽

Flow Paths ◽

Ice Flow

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The last glaciation in Caithness, Scotland: revised till stratigraphy and ice-flow paths indicate multiple ice flow phases

Scottish Journal of Geology ◽

10.1144/sjg2016-001 ◽

2016 ◽

Vol 52 (2) ◽

pp. 77-89 ◽

Cited By ~ 7

Author(s):

Adrian M. Hall ◽

James B. Riding

Keyword(s):

Flow Paths ◽

Ice Flow ◽

Last Glaciation

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Late Quaternary deglaciation of Prince William Sound, Alaska

Quaternary Research ◽

10.1017/qua.2021.33 ◽

2021 ◽

pp. 1-20

Author(s):

Peter J. Haeussler ◽

Ari Matmon ◽

Maurice Arnold ◽

Georges Aumaître ◽

Didier Bourlès ◽

...

Keyword(s):

Sea Level ◽

North Pacific ◽

Late Quaternary ◽

North Pacific Ocean ◽

Ice Sheets ◽

Prince William Sound ◽

Flow Paths ◽

Ice Flow ◽

Cordilleran Ice Sheet ◽

Exposure Ages

Abstract To understand the timing of deglaciation of the northernmost marine-terminating glaciers of the Cordilleran Ice Sheet (CIS), we obtained 26 10Be surface-exposure ages from glacially scoured bedrock surfaces in Prince William Sound (PWS), Alaska. We sampled six elevation transects between sea level and 620 m and spanning a distance of 14 to 70 km along ice flow paths. Most transect age–elevation patterns could not be explained by a simple model of thinning ice; the patterns provide evidence for lingering ice cover and possible inheritance. A reliable set of 20 ages ranges between 17.4 ± 2.0 and 11.6 ± 2.8 ka and indicates ice receded from northwestern PWS around 14.3 ± 1.6 ka, thinned at a rate of ~120–160 m/ka, and retreated from sea-level sites at 12.9 ± 1.1 ka at a rate of 20 m/yr. The retreat rate likely slowed as glaciers retreated into northern PWS. These results are consistent with the growing body of reported deglacial constraints on collapse of ice sheets along the Alaska margin indicating collapse of the CIS soon after 17 ka. These data are consistent with paleotemperature data indicating that a warming North Pacific Ocean caused catastrophic collapse of this part of the CIS.

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