Today

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Today

• From primary productivity to
• Deep sea sediments
• Climate change and variations
• Oxygen Isotopes
• Early Earth
• Test Thursday

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Deep Ocean Sediment
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Deposition in the Deep Sea

• From the Continents
• rivers
• glaciers
• dust
• turbidites

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Deposition in the Deep Sea

• From primary productivity
• organismal death
• Settling through the water column
• Deposition of decayed particles on seafloor
• Decomposition or burial

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Deposition in the Deep Sea

• From precipitation
• deep sea vents
• nodules

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Sediment Composition

• Inorganic materials from the land and air
• Mud (clay and silt)
• Sands and gravels
• Glacial sediments (till, dropstones)
• Organic materials from the land and sea (and air)
• Soft tissues
• Hard tests
• Precipitates
• Manganese nodules, crusts
• Hydrothermal vent minerals

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Deep Sea Sedimentation

• Manganese Nodules
• Left image from http//web.ngdc.noaa.gov/mgg/image
  /nodule.gifRight image from http//bell.mma.edu
  /jbouch/MnNodules.GIF

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Classifications of Sediment

• Inorganic Sources
• Lithogenous derived from rock
• Hydrogenous derived from water
• Carbonates, phosphorites, manganese nodules
• Organic Sources
• Biogenous
• Calcareous ooze
• Siliceous ooze

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Specific Types of Sediment(see figure 3.20)

• Terrigenous sediment
• Calcareous ooze
• Red Clay
• Hydrogeneous sediment
• Siliceous ooze
• Ice rafted sediment

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Paleoceanography

• Study of the oceans past
• The landfill of the sea
• Constantly recording through deposition
• What are some stories that the sediments tell?

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History Recorded

• Of what are the sediments in the deep sea
  composed?
• What are the primary constituents?
• What are the species involved?
• What are their geographic distributions?
• Have these geographic distributions changed
  through time?
• How could you tell if they had or not?
• What methods would you use in order to understand
  the changes that have occurred in the System?

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Mapping the deep sea

• Why would you do it?
• What would you measure?
• How would you do it?
• What would you need?

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Sediments

• Map of sediment distributions in the worlsds
  oceans

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Controls on carbonate oozes

• Calcite Compensation Depth CCD
• Line where carbonate dissolve faster than can be
  deposited
• Snow line
• ---picture of CCD and position with depth

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Sediment Sources

• Terrigenous genesis from land
• Neritic coastal sediments
• Pelagic deep sea sediments
• Preserved biological organisms can be very
  helpful in identifying the environment of
  deposition!

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Oxygen Isotope Correlation

• Correlation by fluctuations of 18O16O

Dated Ash Layer
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Changes In Oxygen Isotopes

• Results from fractionation (unequal separation)
  of oxygen isotopes
• Lighter 16O water is more easily evaporated

glacial
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Changes In Oxygen Isotopes

• When clouds reach high latitudes/land, water
  enriched in 16O forms precipitation
• If cold, 16O water freezes in glaciers and stays
  on land, which increases oceanic 18O16O.
• If warm, 16O flows back to oceans, which lowers
  oceanic 18O16O.

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Changes In Oxygen Isotopes
Glacial Period 16O water frozen in ice
ltlt18O16O
glacial
preferential raining out of 18O water
ltlt18O16O
lt18O16O
Interglacial 16O water returns to oceans
preferential evaporation of 16O water
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Oxygen Isotope Correlation
seafloor

• Correlation by fluctuations of 18O16O