Jökull - 01.01.2004, Page 46

Jessica Black et al.
Figure 7. Seismic profile across the Northern Flats and up the face of the Prograding Delta (see Figure 2 for
location). Seismic units 2, 3 and 4 thicken landward, confirming that the lake must have been substantially
wider in the past, and that the Hvítárnes Delta has prograded into the lake. Parabolic reflectors along the delta
face are indicative of regular slope failures of the actively prograding delta, a phenomenon confirmed by the
physical characteristics of sediment core 02HVT-3 which is projected on the seismic line (see text for discus-
sion). – Endurvarpslína eftir nyrsta hluta Hvítárvatns framan við Hvítárnes óseyrina. Endurvarpseiningar 2,
3 og 4 þykkna í átt að landi, sem staðfestir hugmyndir um stærra vatn í fyrndinni. Fleygboga mynstur eftir
óseyrarhlíðinni benda til óstöðugleika og virkrar framrásar óseyrarinnar. Þetta kemur einnig fram í setkjarna
02HVT-3 sem hefur verið varpað á endurvarpsmælilínuna.
the acoustic signal with the lithostratigraphy of sedi-
ment cores obtained in 2002. Once a meaningful sub-
division of the seismic signal is defined, the acous-
tic properties of these units are distinctive enough on
their own that they can be traced throughout the six
sediment accumulation areas. An isopach map of total
sediment fill is shown in Figure 4 and isopach maps of
sediment thickness and volumes for each of the seis-
mic units above the Basal Unit are shown in Figure 9.
The Basal Unit is for the most part acoustically
transparent (Figure 7, 8 and 9), with an uneven up-
per surface. In some profiles it has faint sub-parallel
reflectors that are difficult to resolve over distances
more than a few hundred meters. They do not fit the
characteristics of multiple reflections from shallower
units, and we consider them to represent localized
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