Ocean sediment

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Ocean sediment

• Various materials settle through the water column
  and accumulate on the ocean floor
• Layers represent a record of Earth history,
  including
• Movement of tectonic plates
• Past changes in climate
• Ancient ocean circulation patterns
• Cataclysmic events

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Collecting ocean sediment

• Specially designed ships collect cores by rotary
  drilling
• Cores allow scientists to analyze ocean sediment

Figure 4B
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The 4 main types of sediment

• Lithogenous composed of fragments of
  pre-existing rock material
• Biogenous composed of hard remains of
  once-living organisms
• Hydrogenous formed when dissolved materials
  come out of solution (precipitate)
• Cosmogenous derived from outer space

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Origin of lithogenous sediment

• Forms by
• Weathering breakup of exposed rock
• Transportation movement of sediment
• Deposition settling and accumulation

Sediment-transporting media
Figure 4-4
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Dust plume over the Red Sea
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Dust haze over the Atlantic Ocean
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Lithogenous sediment composition

• Most lithogenous sediment is composed of quartz,
  which is
• Abundant
• Chemically stable
• Durable

Figure 4-5
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Lithogenous sediment texture

• Texture includes
• Grain size
• Sorting
• Rounding
• Maturity

Figure 4-7
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Distribution of lithogenous sediment

• Lithogenous sediment occurs as
• Neritic (nearshore) deposits
• Beaches
• Continental shelves
• Turbidites
• Glacial-rafted debris
• Pelagic (deep ocean floor) deposits
• Abyssal clay

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Realistic Shelf Sediment Profile
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Contrast Sedimentation on
______ and _______ Margins
Fig. 4-5
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Sedimentation Processes on ________ ________
Fig. 4-7
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Development of Shelf Sediments on a _______ _____
Present
Known from _____ and _____ data
Fig. 4-6