38' Introduction to Submarine Canyon Map Exercise William Wilcock

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38. Introduction to Submarine Canyon Map
ExerciseWilliam Wilcock
OCEAN/ESS 410
Fall 2007
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Sediment Transport Mechanisms

• Currents and wave motions
• rivers, beaches, shelf (wave base)
• Transport in suspension (fine grains) and bedload
  (coarser grains) transport
• If concentration of suspended sediment is
  sufficient that the density of sediment laden
  waters exceeds that of surrounding seawater, the
  sediment laden fluids will flow downwards hugging
  the seafloor. Transport into deeper water -
  Isopycnal (constant density) flows

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Sediment Transport from Shelf to Deep Waters

• Turbidites
• Debris Flows/Slides

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Debris flows slides vs. turbidity currents

• Debris flows slides
• Highly variable but usually slow (m/yr up to 10
  m/s)
• Not turbulent
• Highly concentrated (individual particles do
  collide)
• Not particularly erosive
• Initiated by catastrophic events (e.g.,
  earthquakes)
• Turbulent
• Turbulent
• Dilute (individual particles dont collide)
• Fast (1-5 m/s, typical up to 25 m/s)
• Erosive
• Initiated by catastrophic events or isopycnal
  flows

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Ignitive (Growing) Turbidity Currents
Feedback loop by which turbulent flow suspends
particles and thus increases the fluid density
(negative buoyancy) driving the flow can operate
in a positive sense such flows are said to be
ignitive - they grow in strength.
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Debrites vs. Turbidites

• Debrites
• Weakley Inversely graded (upward coarsening)
• Thick, but pinch out quickly
• Convoluted bedding
• Turbidites
• Normally graded (upward fining)
• Laterally extensive
• Thin
• Horizontal bedding

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Eel Canyon
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Eel River Drainage Basin
41o00
40o50
40o40
Eel Canyon Maps
124o40
124o30
Eel River Drainage Basin 9000 km2
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(No Transcript)
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Kiwai Valley
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Fly River Tidal River
Courtesy of W. Dietrich
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Kiwai Channel Map
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(No Transcript)
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Gulf of Lions
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Gulf of Lions Floods September 2002

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Cap de Creus Canyon Map