Publication Date:
2017-09-10
Description:
The Mozambique Channel plays a key role in
the exchange of surface water masses between the Indian
and Atlantic Oceans and forms a topographic barrier for
meridional deep and bottom water circulation due to its
northward shoaling water depths. New high-resolution
bathymetry and sub-bottom profiler data show that due to
these topographic constraints a peculiar seafloor morphology
has evolved, which exhibits a large variety of current-
controlled bedforms. The most spectacular bedforms
are giant erosional scours in the southwest, where northward
spreading Antarctic Bottom Water is topographically
blocked to the north and deflected to the east forming
furrows, channels and steep sediment waves along its
flow path. Farther north, in the water depth range of North
Atlantic Deep Water, the seafloor is strongly shaped by
deep-reaching eddies. Steep, upslope migrating sediment
waves in the west have formed beneath the southward flow
of anticyclonic Mozambique Channel eddies (MCEs).
Arcuate bedforms in the middle evolved through an interaction
of the northward flow of MCEs with crevasse splays from
a breach in the western Zambezi Channel levee. Hummocky
bedforms in the east result from an interplay of East
Madagascar Current eddies with overspill deposits of the
crevasse and Zambezi Channel. All bedforms are draped
with sediments indicating that the present-day current
velocities are not strong enough to erode sediments. Hence,
it can be concluded that the seafloor morphology developed
during earlier times, when bottom-current velocities were
stronger. Assuming a sedimentation rate of 20 m/Ma and
a drape of at least 50 m thickness the bedforms may have
developed during the Pliocene Epoch or earlier.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
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isiRev
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