Marine Sedimentation

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Marine Sedimentation

• What is it and where does it come from?

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Table 5-1, p. 103
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Bottom of the Ocean Floor (Antarctica)
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How do we know/How do we get it?
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(No Transcript)
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Ice samples
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(No Transcript)
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River inputs (sedimentation)
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Atmospheric Inputs
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Dust input
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• Based upon water depth, the ocean environment can
  be divided into
• the shelf
• shallow and near a terrigenous source
• the deep ocean basin
• deep and far from a terrigenous source

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Shelf Sedimentation
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• Shelf sedimentation is strongly controlled by
• Tides
• Waves
• Currents
• Their influence decreases with water depth.
• Shoreline turbulence prevents small particles
  from settling in the shallow water.
• Particle size decreases seaward for recent
  sediments.

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• Geologic controls of continental shelf
  sedimentation must be considered in terms of a
  time frame.
• For a time frame up to
• 1000 years, waves, currents and tides control
  sedimentation.
• 1,000,000 years, sea level lowered by glaciation
  controls sedimentation and cause rivers to
  deposit their sediments at the shelf edge and
  onto the upper continental slope.
• 100,000,000 years, plate tectonics determines the
  type of margin that develops and controls
  sedimentation.

4-2 Sedimentation in the Ocean
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Whats in there?

• Forams
• Coccoliths
• Radiolarians (and other Protozoans)
• Diatoms and other Phytoplankton (shells)
• Fecal Pellets and Dead things (marine snow)

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• Major pelagic sediments in the ocean are red clay
  and biogenic oozes.

Foraminifera
Diatoms
Marine Snow
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Foram
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Coccolith
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Radiolarians
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Diatoms
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Fecal Pellet
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What do you get?

• What geologic structures? and where?

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100 mya - Lithified Coccolith Cliffs (Dover,
England)
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Fig. 5-12, p. 111
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Global Deep-Sea Deposits
Sedimentation Rates
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If influx of terrigenous sediment is low and the
water is warm, carbonate sediments and reefs will
dominate.
Distribution of Carbonate Shelves
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• Deep-sea Sedimentation has two main sources of
  sediment
• External terrigenous material from the land
• Internal biogenous and hydrogenous from the sea.

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Deep-Sea Sedimentation