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Hypsometry and volume of the Arctic Ocean and its constituent seas
- Geochem., Geophys., Geosyst
, 2002
"... [1] This paper presents an analysis of the Arctic Ocean and its constituent seas for seafloor area distribution versus depth and ocean volume. The bathymetry from the International Bathymetric Chart of the Arctic Ocean (IBCAO) is used together with limits defining this ocean and its constituent seas ..."
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[1] This paper presents an analysis of the Arctic Ocean and its constituent seas for seafloor area distribution versus depth and ocean volume. The bathymetry from the International Bathymetric Chart of the Arctic Ocean (IBCAO) is used together with limits defining this ocean and its constituent seas from the International Hydrographic Organization (IHO) as well as redefined limits constructed to confine the seas to the shallow shelves. IBCAO is a bathymetric grid model with a resolution of 2.5 2.5 km, which significantly improved the portrayal of the Arctic Ocean seafloor through incorporation of newly released bathymetric data including echo soundings from U.S. and British navies, scientific nuclear submarine cruises, and icebreaker cruises. This analysis of seafloor area and ocean volume is the first for the Arctic Ocean based on this new and improved portrayal of the seafloor as represented by IBCAO. The seafloor area and volume are calculated for different depths starting from the present sea level and progressing in increments of 10 m to a depth of 500 m and in increments of 50 m from 550 m down to the deepest depth within each of the analyzed seas. Hypsometric curves expressed as simple histograms of the frequencies in different depth bins and depth plotted against cumulative area for each of the analyzed seas are presented. The area and volume calculations show that the entire IHO-defined Arctic Ocean makes up 4.3 % of the total ocean area but only 1.4 % of the volume. Furthermore, the IHO Arctic Ocean is the shallowest (mean
A relict landscape in the centre of Fennoscandian glaciation: Geomorphological evidence of minimal Quaternary glacial erosion
- Geomorphology
, 2002
"... The Parkajoki area in northeastern Sweden is situated near the central area of Fennoscandian glaciation. Despite its location, the area is dominated by landforms induced by subaerial weathering and erosion processes, such as well-developed tors and associated saprolites, boulder fields, and boulder ..."
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The Parkajoki area in northeastern Sweden is situated near the central area of Fennoscandian glaciation. Despite its location, the area is dominated by landforms induced by subaerial weathering and erosion processes, such as well-developed tors and associated saprolites, boulder fields, and boulder depressions. The glacial geomorphology is dominated by lateral and proglacial meltwater channels. Subglacial imprints indicative of thawed-bed conditions and reshaping by glacier sliding (e.g., fluting, drumlins, striae) are lacking. Hence, most of the landscape still exhibits a preglacial appearance. Because of its location, near the central area of glaciation, we attribute preservation to frozen-bed conditions of overriding ice sheets. The widespread distribution of well-developed tors and boulder fields, and the degree of chemical weathering of the bedrock, indicate that the area has been protected from glacial erosion during all glacial cycles since ice sheet initiation in the late Cenozoic. Unlike most other areas with tors in glaciated regions, the Parkajoki area is uniquely situated in the lowlands at 150–400 m.a.s.l. Moreover, this relict landscape is surrounded by glacial landscapes (including drumlins, ribbed moraine, and eskers) of varying age and at similar elevation. Hence, topographical reasons for this area being persistently cold-based cannot be invoked. By inference, we conclude that strain heat release never managed to cancel the initial subglacial permafrost conditions. We attribute this to divergent ice flow towards the convex outline of the ice sheet margin during deglaciations and to the relative roughness of the area compared to its surroundings. The implication is that to explain preservation throughout the Quaternary, all large-scale
2004: Polar MM5 simulations of the winter climate of the Laurentide Ice Sheet at the LGM
- J. Climate
"... Optimized regional climate simulations are conducted using the Polar MM5, a version of the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5), with a 60-km horizontal resolution domain over North America during the Last Glacial Maximum (LGM, 21 000 calendar years ago), when mu ..."
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Optimized regional climate simulations are conducted using the Polar MM5, a version of the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5), with a 60-km horizontal resolution domain over North America during the Last Glacial Maximum (LGM, 21 000 calendar years ago), when much of the continent was covered by the Laurentide Ice Sheet (LIS). The objective is to describe the LGM annual cycle at high spatial resolution with an emphasis on the winter atmospheric circulation. Output from a tailored NCAR Community Climate Model version 3 (CCM3) simulation of the LGM climate is used to provide the initial and lateral boundary conditions for Polar MM5. LGM boundary conditions include continental ice sheets, appropriate orbital forcing, reduced CO2 concentration, paleovegetation, modified sea surface temperatures, and lowered sea level. Polar MM5 produces a substantially different atmospheric response to the LGM boundary conditions than CCM3 and other recent GCM simulations. In particular, from November to April the upper-level flow is split around a blocking anticyclone over the LIS, with a northern branch over the Canadian Arctic and a southern branch impacting southern North America. The split flow pattern is most pronounced in January and transitions into a single, consolidated jet stream that migrates northward over the LIS during summer. Sensitivity experiments indicate that the winter split flow in Polar MM5 is primarily due to mechanical forcing by LIS, although model
Cosmogenic exposure dating in Arctic glacial landscapes: implications for the glacial history of northeastern Baffin
- Canadian Journal of Earth Sciences
, 2005
"... Abstract: Cosmogenic exposure dating and detailed glacial-terrain mapping from the Clyde Foreland, Baffin Island, Arctic Canada, reveal new information about the extent and dynamics of the northeastern sector of the Laurentide Ice Sheet (LIS) during the last glacial maximum (LGM). The Clyde Foreland ..."
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Abstract: Cosmogenic exposure dating and detailed glacial-terrain mapping from the Clyde Foreland, Baffin Island, Arctic Canada, reveal new information about the extent and dynamics of the northeastern sector of the Laurentide Ice Sheet (LIS) during the last glacial maximum (LGM). The Clyde Foreland is composed of two distinct landscape zones: (1) glacially scoured terrain proximal to the major sources of Laurentide ice that flowed onto the foreland, and (2) ice distal unscoured sectors of the foreland. Both zones are draped with erratics and dissected by meltwater channels, indicating past ice cover. We interpret the two landscape classes in terms of ice sheet erosive ability linked with basal thermal regime: glacially scoured terrain was occupied by erosive warm-based ice, and unscoured terrain was last occupied by non-erosive cold-based ice. Cosmogenic exposure ages from>100 erratics from the two landscape types have different age distributions. Cosmogenic exposure ages from the glacially scoured areas suggest ice cover during the LGM, followed by deglaciation between 15 and 12 ka. In the unscoured lowlands, the cosmogenic exposure ages have multiple modes ranging between 12 and 50 ka, suggesting multiple periods of cold-based ice cover during the last glacial cycle. In landscapes covered by cold-based ice, large numbers of cosmogenic exposure ages are required for elucidating glacial histories. Résumé: La détermination des âges d’exposition aux rayonnements cosmogéniques et une cartographie détaillée du terrain glaciaire de l’avant-pays Clyde, île de Baffin, dans l’Arctique canadien, révèlent de nouvelles informations sur
The Eastern Limit of Beringia: Mammoth Remains from Banks and Melville Islands, Northwest Territories
, 2005
"... ABSTRACT. Two mammoth fossils (presumably woolly mammoth, Mammuthus primigenius) from northwestern Banks and ..."
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ABSTRACT. Two mammoth fossils (presumably woolly mammoth, Mammuthus primigenius) from northwestern Banks and
Re-evaluating the Relevance of Vegetation Trimlines in the Canadian Arctic as an Indicator of Little Ice Age Paleoenvironments
, 2005
"... ABSTRACT. The origin of trimlines associated with the so-called “lichen-free ” areas in the Canadian Arctic has been attributed both to perennial snowfield expansion during the Little Ice Age (LIA) and to seasonally persistent snow cover in more recent times. Because of the disparate hypotheses (eco ..."
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ABSTRACT. The origin of trimlines associated with the so-called “lichen-free ” areas in the Canadian Arctic has been attributed both to perennial snowfield expansion during the Little Ice Age (LIA) and to seasonally persistent snow cover in more recent times. Because of the disparate hypotheses (ecological versus paleoclimatic) regarding the formation of these trimlines, their use as a paleoclimatic indicator has been abandoned for more than two decades. We re-examine this debate and the validity of the opposing hypotheses in the light of new regional mapping of trimlines across the Queen Elizabeth Islands (QEI). The ecological hypothesis—insufficient duration of the growing season resulting from seasonally persistent snow cover—fails to account for the poikilohydric nature of lichens and their ability to endure short growing seasons. It cannot adequately explain the existence of sharp trimlines or account for the occurrence of those trimlines on sparsely vegetated carbonate terrain. Furthermore, trimlines outlining the former extent of thin plateau ice caps are accordant with trimlines associated with former perennial snowfields, indicating that these trimlines record snow and ice expansion during the LIA rather than the seasonal persistence of more recent snow cover. We suggest that these features represent an important LIA climate indicator and should therefore be used for paleoclimatic reconstruction.
Contents lists available at ScienceDirect Quaternary Science Reviews
"... journal homepage: www.elsevier.com/locate/quascirev ..."
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in the Eastern Canadian
, 2001
"... Our conceptions of the NE sector of the Laurentide Ice Sheet (LIS) at the Last Glacial Maximum (LGM) have evolved through three major paradigms over the past 50 years. Until the late 1960s the conventional view was that the Eastern Canadian Arctic preserved only a simple deglacial sequence from a LI ..."
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Our conceptions of the NE sector of the Laurentide Ice Sheet (LIS) at the Last Glacial Maximum (LGM) have evolved through three major paradigms over the past 50 years. Until the late 1960s the conventional view was that the Eastern Canadian Arctic preserved only a simple deglacial sequence from a LIS margin everywhere at the continental shelf edge (Flint Paradigm). Glacial geologic field studies began in earnest in this region in the early 1960s, and within the first decade field evidence documenting undisturbed deposits predating the LGM led a pendulum swing to a consensus view that large coastal stretches of the Eastern Canadian Arctic remained free of actively eroding glacial ice at the LGM, and that the most extensive ice margins occurred early in the last glacial cycle. This Minimalist Paradigm dominated until the late1980s when an expanded data set from shallow marine studies indicated LGM ice at least locally reached the continental shelf. Within the past decade the marine data, coupled with new evidence from lake sediments and cosmogenic exposure dates on moraines and glaciated terrain in the Eastern Canadian Arctic has led to a new paradigm that better reconciles the terrestrial and marine evidence. Collectively, these lines of evidence indicate that all of southern Baffin Island was glaciated at the LGM, but that some coastal uplands north of Cumberland Sound remained above the limit of actively eroding glacial ice, even though outlet glaciers reached the continental shelf in front of most fiords and sounds. The
Definition
"... Dating glacial landforms. Applying geochronological tools (e.g., relative- and absolute-dating methods, etc.) to glacial landforms (e.g., moraines) to yield the timing of past glaciation (Moraine and Glacial Geomorphology and Landforms Evolution). ..."
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Dating glacial landforms. Applying geochronological tools (e.g., relative- and absolute-dating methods, etc.) to glacial landforms (e.g., moraines) to yield the timing of past glaciation (Moraine and Glacial Geomorphology and Landforms Evolution).
er, Woos
, 2014
"... ings (discontinuous continuous records/ ends and centennial mountain tree lines, tors that drove the olocene, to the late to overall summer and in the tropical arly Holocene to the hern South America ossibly triggered by e4.2 ka, 3.8e3.4 ka, to general cooling periods of low solar nce to widespread ..."
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ings (discontinuous continuous records/ ends and centennial mountain tree lines, tors that drove the olocene, to the late to overall summer and in the tropical arly Holocene to the hern South America ossibly triggered by e4.2 ka, 3.8e3.4 ka, to general cooling periods of low solar nce to widespread of glacier advances, CE) but the record f ages suggests that ecadal variations of may have played a context of Holocene glaciation, though the retreating glaciers in most parts of the Northern Hemi-sphere are still larger today than they were in the early and/or mid-Holocene. The current retreat,
