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Figure 8.
Core Hu98-05 from the Sohm Abyssal Plain (SAP) with down-core plots of (a) sediment facies, (b) carbonate
(%), (c) magnetic susceptibility (SI units), (d) L color, (e) total organic carbon (% TOC), and (f)
14
C-AMS (ka) versus
depth (m). It was retrieved at 5232 m water depth from the northeastern SAP just down
flow from the terminus of the
NAMOC. Four calibrated
14
C-AMS dates in N. pachyderma (s) were used to constrain the stratigraphy between 1.7 and
3.71 m. Lack of N. pachyderma (s) prevented determination of
18
O from this core. H0 is denoted by the horizontal gray
δ
bar, whereas
“
a,
”
the lightly shaded bar, represents the underlying carbonate-rich sediments with high TOC (%).
the bulk of the sediment seaward of Hudson Strait during
all three H events.
The similar sedimentological character of the H0 and H1
beds in cores Hu97-16 and Hu97-09 (Figures 2 and 3)
suggests similar depositional processes during the two
events. Variations in thickness may result from differences
in the advection trajectory of the icebergs and surface
plume, but the >50% smaller mean thickness of H0 com-
pared with H1 suggests a smaller and/or shorter discharge
of sediment. This is consistent with the less depleted
δ
5.4. Distribution of the H0 Detrital Carbonate Bed
The distribution of the high-carbonate H0 bed is quite
different from H1 and H2, although all are recognized pri-
marily by the presence of carbonate-rich sediments dis-
charged through Hudson Strait. H0 is virtually absent in the
Labrador Sea southeast of core Hu97-16, whereas H1 and H2
are widespread. The variation in their character and distribu-
tion would be influenced by several factors: (1) the volume
of fresh waters discharged during ice stream retreat, (2) the
position of the ice margin, (3) the strength of the Labrador
Current, and (4) the extent of sea ice cover in the Labrador
Sea.
18
O
Nps
signature in cores Hu97-09, Hu97-16, and Hu91-
94 in H0 and the absence of significant depleted
δ
18
O
Nps
signal in many Labrador Sea cores. It thus seems likely that
the volume of meltwater discharged during H0 was less
than during H1.
Dinoflagellate assemblage data [Hillaire-Marcel et al.,
2007; de Vernal et al., 2001] show that sea ice cover varied
from 9 to 12 months year
1
during both H0 and H1, not only
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