Submarine
Channel Initiation and Evolution: an Experimental Approach
Kane, Ian1, Jeff Peakall1,
William. D. McCaffrey1 (1)
Density flows in the subaqueous
environment have different characteristics to their subaerial counterparts. In
the subaqueous case, flows lack a free upper surface and there is a reduced
density contrast between the flow and the ambient fluid. These factors alone
suggest that the mechanics of the initiation, growth and abandonment of
submarine slope channels may be very different from fluvial channels. Here we present
a series of experiments designed to investigate the key factors controlling
incipient channelisation. In particular, a key question is whether levee growth
alone is enough to promote confinement, or whether contemporaneous channel
thalweg incision is necessary? Experiments were performed in a flume tank 0.5 x
6 m in length, and 1.5 m deep. In the tank a sediment tray was placed on an
adjustable slope table. At the updip end a continuous input of saline was
introduced into the fresh water and allowed to spill onto a flat sediment
surface. A lightweight polymer sediment analogue was used which was capable of
being transported by the saline input current. Sustained flows revealed an
autocyclic pattern of updip incision, down dip lobe building, lobe incision, in
the form of a sinuous channel with levees, and updip canyon backfilling. The
continuous input system allowed us to stop the system and take bathymetric
profiles enabling detailed documentation of the evolution of the system.
Results are presented and some comparisons to modern and subsurface systems are
made; implications for hydrocarbon exploration are discussed.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California