Jökull - 01.01.2004, Page 48

Jessica Black et al.
Figure 9. Isopach maps illustrating the thickness of the sediment fill for seismic units 1 through 4 across that
portion of Hvítárvatn covered by the seismic survey. Differences in the distribution of sediment fill define the
changing dominance of sediment delivery systems through the Holocene. – Jafnþykktarkort sets í einingum 1
til 4. Breytingar í setþykkt benda til breytinga í setframburði til vatnsins á mismunandi tímum nútíma.
record, provided access to relatively deep portions of
the stratigraphic succession (Figures 2 and 5). Core
02HVT-04 is a 5.1 m long core recovered in a single
drive centered at the bottom of the iceberg furrow, tar-
geting the oldest sediment in the basin, whereas core
02HVT-05, taken only 30 m to the east of 02HVT-04
where the water depth was 7 m shallower, was posi-
tioned to recover the undisturbed upper 5.4 m of sed-
iment. The two cores do not overlap, and it is esti-
mated that about 2 m of unsampled sediment separate
the recovered sections. The upper 1.5 m of sediment
in 02HVT-04 is disturbed, and probably reflects infill
from the steep, scoured wall. The lower 3.5 m of the
core is horizontally stratified and is considered to be
intact.
Core 02HVT-04 is dominated by finely laminated
gray sedimentary laminae, interspersed with several
thick tephra layers, some in excess of 5 cm thick, and
many thinner tephra layers (Figure 10). The thick-
est tephra layers correspond to a series of pronounced
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