Material Fluxes on the Surface of the Earth (1994) / Chapter Skim
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Sediment Fluxes Along High-Latitude Glaciated Continental Margins: Northeast Canada and Eastern Greenland
Sediment Fluxes Along High-Latitude Glaciated Continental Margins: Northeast Canada and Eastern Greenland
Pages 99-115
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From page 99... ...
, the net flux of sediment to the seafloor can be derived from radiometrically dated cores, or can be modelled. In the eastern Canadian Arctic, the net average net flux to the seafloor varied between 600 and 1300 kg/m2/ka in the outer fiord basins, to about 400 kg/m2/ka in shelf/troughs, to 0 to 50 kg/m2 on the shelf proper.
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From page 100... ...
10-1 11. In the past two years, there have been several international symposia on glacial marine sediments and processes, and several major review papers have been published that seek to synthesize our knowledge of these processes and FIGURE 7.1 LANDSAT image of the fiord coast of east Baffin Island, showing the sea ice breaking up (July 22, 1977)
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From page 101... ...
We also examine the climatic and glaciological controls on sediment flux. In the second part, we illustrate some of these aspects by examining two specific regions, the first being the borderland of the eastern Canadian Arctic, fronting Baffin Bay, and the second being part of the East Greenland shelf.
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From page 102... ...
In areas where there is a large number of icebergs drifting along the shelf and into the outer fiords (east Baffin Island and East Greenland) the sediment would coarsen seaward and diamict might be deposited on the shelf because Fn_ has a significant component of the Fs_ flux (Figure 7.21(e.g., Kravitz, 1982~.
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From page 103... ...
The adjacent continental shelves are often marked by distinct "banks" where water depths are <200 m. Climate and Oceanography Figure 7.4 illustrates the differences in temperature and precipitation between two contrasting glaciated borderlands—one from the eastern Canadian Arctic and the other from southeast Alaska.
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From page 104... ...
is that the production of run-off from snow/ice melt and rainfall is restricted to around 90 days in the eastern Canadian Arctic but is potentially year-round in southeast Alaska. Strong winds are a feature of areas adjacent to ice sheets and glaciers.
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From page 105... ...
resulting in erosion and recycling of outwash and raised glacial marine sediments. The Deglacial Sediment Flux Cycle The flux of sediment from glaciated margins to the marine environment is a function of five major processes that vary spatially and temporally through a glacial to interglacial cycle, 105 i.e., the past 10 ka (Figure 7.84.
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From page 106... ...
The rate of sedimentation associated with each is shown in a relative sense versus time and distance from the major sediment source. DEGLACIAL TO INTERGLACIAL FIORD/SHELF SEDIMENT FLUX E ~ of ct D: ent Lyme Pre Present O ~ Time 1 Mouth / In this section we examine data from the fiords and shelf of the eastern Canadian Arctic (Figures 7.1 and 7.4)
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From page 107... ...
tu HldBO 31UWIXOUddU o o o ~ ._ .~.
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From page 108... ...
Analysis of the contributions of the various measurement errors to errors in estimation indicates that the 95 percent confidence limit in estimating the sediment accumulation (age +20 percent and dry volume density +10 percent) is +14 percent, and no worse than +20 percent (Taylor, 1982~.
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From page 109... ...
Clay-size sediment was the major size fraction at MC4.1, whereas at MC83.6 the sediment was about equal in terms of sand/silt/clay. During the next 3 ka, the Laurentide Ice Sheet was melting rapidly across the eastern Canadian Arctic (cf., Dyke, 1974; Dyke and Prest, 1987)
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From page 110... ...
Although sediment densities were not reported, the sediment flux is probably of the order of about 1600 kg/m2/ka, a figure similar to that observed in the outer Baffin Island fiord basins during deglaciation (Figure 7.141. Representative Fni's for clay-size materials over the past 10 ka are shown as Figure 7.16 for fiord, shelf, and the ODP 645 site in Baffin Bay (cf., Srivastava et al., 19871.
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From page 111... ...
FIGURE 7.17 Sediment flux over the past 8 ka from Baffin Island fiord sites, to shelf-trough sites, to Baffin Bay (from Andrews, 1987b)
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From page 112... ...
Studies on these timescales should be supplemented, whenever possible, with the deployment of sediment traps to study the nature of the present sediment flux over a period of 1 to 3 years. In the middle arctic area of western Baffin Bay, on a deglacial/interglacial timescale, the net downward flux of sediment in Baffin Island outer fiord basins is of the order of 600 to 800 kg/m2/ka, compared with 200 to 300 kg/m2/ka in the adjacent shelf-troughs (Figure 7.13; Andrews, 1987b)
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From page 113... ...
. The patterns of glacial erosion across the eastern Canadian Arctic, in Quaternary L MARGINS ~3 Environments: Ba~n Island, Baffin Bay and West Greenland, J
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From page 114... ...
. Northwest Labrador Sea stratigraphy, sand input and paleoceanography during the last 160,000 years, in Quaternary Environments: Eastern Canadian Arctic, Ba~in Bay and Western Greenland, J
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From page 115... ...
. Suspended sediment loads along the coast of NE Baffin and Bylot islands, in Sedimentology of Arctic Fjords Experiment: Data Report, Volume 3, J
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