FIGURE 7.16 Seafloor flux Fn↓ of clay-size particles and clay-size mineralogy of fiord, shelf, and deep-sea sediments (Baffin Island to Baffin Bay).

lesser amounts in the fiords and deep sea. These data suggest that the carbonate was brought into the area via the Baffinland Current, probably in the form of both suspended particulates, from meltwater, and as material contained in icebergs.

Figure 7.17 presents a summary (Andrews, 1987b) for fiord to deep sea Fn↓ over the past 8 ka. These data do not include the sites on Figure 7.14, however, they also suggest that the Fn↓ decreases by about one-half over a distance of 30 to 40 km (see Figure 7.14).

It must be emphasized that this study considers Fn↓ along a narrow strip of the seafloor. Flux calculations, from cores, can be partly checked by the geometries of the acoustic reflectors (Figure 7.10), however, this only provides a two dimensional view of the sediment architecture (e.g., Gilbert, 1985). To be fully representative, so that we can make volume calculations for entire systems, we require cross-fiord and cross-trough seismic stratigraphies.

The East Greenland Margin

Kangderlugssuaq Fiord is a deep re-entry into the heavily glaciated margin of East Greenland. Seaward from the fiord a deep trough (Figure 7.9) cuts across the shelf. In 1988, a WHOI cruise collected a suite of 10-cm diameter gravity cores (1 to 2 m in length) from the trough floor and shelf. Three cores were shipped to the University of Colorado for study (Figure 7.9; Table 7.1). Wet and dry volume densities were measured and a series of basal core dates were obtained on hand-picked foraminifera. Our objective in this ONR supported study was to examine the fiord to deep-sea sediment flux.

The sediments in cores 5A and 10A were principally massive to laminated muds with some dropstones. The lowermost 4 cm in core 10A is a diamict. In deeper water on the slope, the sediment in core 17B was a diamict. Prior to this work we know of no radiocarbon dates from the East Greenland Shelf, although some may exist.

The stonyness of core 17B precluded precise measurements of the dry volume density, but in the other two cores (5A and 10A) it was surprisingly low, with medians of 690 and 860 kg/m3. The AMS basal dates and their depths in the cores (Table 7.2) imply average sediment fluxes during much of the Holocene of 60 kg/m2/ka and 67 kg/m2/ka at sites 5A and 10A, respectively. These initial results give fluxes that are an order of magnitude less than the trough cores we have from the eastern Canadian Arctic shelf (Jennings, 1986; Andrews, 1987b; this chapter). At this stage these results are intriguing but need a wider regional context before their value can be adequately assessed; this will come from work on other cores collected during the cruise, plus planned future work on the shelf and in the adjacent fiords. Additional AMS14C dates, processed for the core tops, indicate continuous sedimentation to be present.

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). The numbers in brackets refer to the number of cores used in establishing the range of estimates.

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