| 1. |
- De Angelis, Hernán
(författare)
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Glacial geomorphology of the east-central Canadian Arctic
- 2007
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Ingår i: Journal of Maps. - 1744-5647. ; v2007, s. 323-341
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Tidskriftsartikel (refereegranskat)abstract
- This article describes palaeoglaciological mapping of the portion of the Canadian Arctic formerly covered by north-easternmost Laurentide Ice Sheet. The mapped area stretches between the meridians 106°W and 61°W, and the parallels 60°N and 75°N, embracing an area of 3.19 x 10^6 km^2. The work was focused on determining the location of landforms that are required as input for a glaciological inversion model, i.e. glacial lineations, eskers, moraine ridges, ribbed moraine and De Geer moraines; and forms the basis of a reconstruction of the geometry and evolution of palaeo-ice streams in this portion of the Laurentide Ice Sheet. Emerged areas were mapped through the geomorphological interpretation of Landsat 7 Enhanced Thematic Mapper Plus (ETM+) satellite images. Information on striae and other minor indicators of glacial activity were extracted from maps and reports by the Geological Survey of Canada, published articles and, on a few locations, by the author's own observations. Information on landforms located on some submerged areas where extracted from publicly available sonar surveys. All data were digitally processed within a Geographical Information System and stored in a spatially enabled database. The results are presented as a printable map at 1:2,400,000 scale.
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| 2. |
- De Angelis, Hernán
(författare)
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Larsen Ice Shelf
- 2007
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Annan publikation (övrigt vetenskapligt/konstnärligt)
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| 3. |
- De Angelis, Hernán, et al.
(författare)
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Palaeo-ice streams in the Foxe/Baffin sector of the Laurentide Ice Sheet
- 2007
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 26:9-10, s. 1313-1331
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we describe mapping of palaeo-ice streams in the Foxe/Baffin sector of the Laurentide Ice Sheet by means of geomorphological interpretation of high-resolution satellite images. Our interpretations were guided by a glaciological inversion scheme, aided by digital elevation models, publicly available sonar surveys and field studies. As a result, we produced a map depicting the location, geometry and relative temporal changes of palaeo-ice streams and analysed their palaeoglaciological implications for the Foxe/Baffin sector. We conclude that in the period between the Last Glacial Maximum and approximately 7.0 kyr BP, the Foxe/Baffin sector was largely drained by topographically controlled outlet glaciers and ice streams, which were organized in a relatively stable pattern. During this time, large areas of Melville Peninsula and central Baffin Island were subject to cold-based conditions. Between 7.0 and 6.0 kyr BP, the Foxe/Baffin sector collapsed catastrophically in the Foxe Basin, after which its remnant portion became confined to Baffin Island. During this collapse, rapid successions of small transient ice streams occurred along wide, loosely defined topographical corridors in two sectors of Baffin Island. The presently available landform archive on emerged land is not sufficient to conclusively support the existence of fully scaled ice streams along the whole length of Hudson Strait. As an alternative solution, we propose that topographically controlled ice streams might have occurred along the deepest parts of Hudson Strait, with attendant cold-based ice zones on marginal areas and islands at the head of the strait.
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| 4. |
- De Angelis, Hernán, 1974-
(författare)
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Palaeo-ice streams in the north-eastern Laurentide Ice Sheet
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents a palaeoglaciological study aimed to determine the location, geometry and temporal evolution of palaeo-ice streams of the north-easternmost Laurentide Ice Sheet. The work was accomplished through the geomorphological interpretation of satellite imagery over 3.19 x 106 km2 of the Canadian Arctic, using a glaciological inversion scheme. Ice streams were active in this region during most of the time between the Last Glacial Maximum and the last deglaciation. A web of ice streams and inter-ice stream areas existed. Three major ice stream networks are identified: the M'Clintock Channel, Gulf of Boothia – Lancaster Sound and Hudson Strait. The M'Clintock Channel bears the most complex landform record, comprising three generations of palaeo-ice streams. Their location was weakly controlled by the subglacial topography and their geometry was determined by frozen-bed portions of the ice sheet, thus providing evidence for pure ice streams in the Laurentide Ice Sheet. In contrast, the more pronounced relief of the Gulf of Boothia – Lancaster Sound corridor supported topographically controlled ice streams. The landform record on emerged land along Hudson Strait is insufficient to support the existence of ice streams. It is therefore proposed that ice streams were constrained within the deep parts of the strait while flanked by cold-based zones on the margins. Small transient ice streams on Baffin and Prince of Wales islands drained local remnant ice caps during the collapse of the ice sheet. Analysis of the controls on the location and flow of palaeo-ice streams suggests that the interaction between the subglacial topography and thermal state of the substrate plays a more fundamental role than the geology. It is concluded that the behaviour of ice streams cannot be explained in terms of environmental controls alone, but the complex dynamics of ice stream shear margins and onset zones must be considered.
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| 5. |
- De Angelis, Hernán, et al.
(författare)
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Snow zonation on Hielo Patagónico Sur, Southern Patagonia, derived from Landsat 5 TM data
- 2007
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181. ; 59, s. 149-158
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Tidskriftsartikel (refereegranskat)abstract
- Hielo Patagónico Sur (HPS), an icefield in Southern Patagonia, is the largest temperate ice mass in the southern hemisphere. Despite continued research efforts during the last decade many glaciological variables, especially mass balance, are still poorly known. This is partly because access to the icefield is difficult due to remoteness and persistent harsh weather conditions. Therefore, remote sensing appears to be a more suitable tool for the acquisition of data. In this work we present a remote sensing study of snow zonation on HPS using Landsat 5 Thematic Mapper data acquired on 12March 2001. By using image processing and classification techniques, proved to be useful in other glaciated regions, we map for the first time the extent and occurrence of major snow zones on the whole HPS. We separate between two classes of ice and three classes of snow. Ice facies are classified as bare or debris (i.e. dirt) covered ice, covering 2454 km2 and 777 km2 respectively, or 18.4% and 5.8% of the icefield on the day of image acquisition. Snow types are classifiedaccording to spectral differences in the images, following the glacier facies concept. Two of the three snow cover types are interpreted to represent differences in snow grain size within a fairly homogeneous snowpack whereas the third one is interpreted to represent the slush zone. A first order altitudinal control on the distribution of these snow facies is evident. In addition, our results show that snow accumulation on HPS is markedly controlled by the interaction of strong west–northwest snow-bearing winds and the roughmountainous terrain. In order of decreasing altitude we find that the two snow facies and the slush facies occupy 3819 km2, 3292km2 and2295 km2 respectively, or 28.6%, 24.6%and 17.2%of the icefield, on the day of image acquisition. Estimates of equilibrium line altitude using our results yield values of 800–900 m above sea level for the western side and 1500–1600 m above sea level for the eastern side, with an accumulation area ratio of 0.74.
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