Jökull - 01.01.2004, Page 43

Sediment thickness and erosion rates within Hvítárvatn, central Iceland
Figure 4. Isopach map of the total thickness of sediment deposited in the main basin of Hvítárvatn over the last
10,000 years. Jafnþykktarkort af því seti sem setst hefur til síðustu 10,000 árin í meginsetdæld Hvítárvatns.
to 20 m water depth at the edge of the Central Deep
(Figure 3). Only a thin layer of sediment is preserved
in this part of the lake (Figure 4), ranging from <10
to a maximum of ca. 18 m thickness. The shallower
portions of the Southern Shallows experiences wind
driven re-suspension of sediment, preventing thick
sediment sequences from being deposited here.
The LIA terminal moraines separate heavily dis-
turbed sediment proximal to the moraines (LIA Scour
Zone) from comparatively undisturbed sediment in
the rest of the basin. The seismic units identified in
the other depocenters of Hvítárvatn are truncated by
the LIA moraines (Figure 5). The lack of acoustically
stratified sediment proximal to the moraines indicates
sediment in the LIA Scour Zone was eroded and /or
disturbed by the LIA glacier advance.
The sediment fill is thickest in the Central Deep,
reaching at least 65 m thickness in the deepest parts
of the basin (Figure 3). The uppermost section in-
cludes acoustically transparent ponded sediment in-
terspersed with acoustically stratified sediment, in-
dicative of sediment gravity flows (Figure 6). Based
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