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2011-03-08 16:23:57
Oceanography test

Lecture 4 - Marine Sediments
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  1. What are examples and properties of Lithogenous sediments
    • Eroded rock fragments from land
    • Reflect composition of rock from which derived
    • Most lithogenous sediments at continental margins
    • Coarser sediments closer to shore
    • Finer sediments farther from shore
    • Mainly mineral quartz (SiO2)
  2. How are Neritic sediments distributed and in which regions are they normally found?
    • Shallow water deposits
    • Close to land
    • Dominantly lithogenous
    • Typically depositedquickly
  3. What are som Types of neritic lithogenous sediments
    • Beach deposits
    • Mainly wave-depositedquartz-rich sands
    • Continental shelf deposits
    • Relict sediments
    • Turbidite deposits
    • from turbidity currrents
    • Glacial deposits
    • High latitude continental shelf
  4. How are Pelagic sediments distributed and in which regions are they normally found?
    • Deeper water deposits
    • Finer-grained sediments
    • Deposited slowly
  5. What are the most common sources of fine pelagic lithogenous sediments?
    • Volcanic ash (volcanic eruptions)
    • Wind-blown dust
    • Fine-grained material transported by deep ocean currents
  6. what are the main qualities of Abyssal clay (red clay) and how are they transported?
    • At least 70% of clay-sizedgrains from continents
    • Transported by winds andcurrents
    • Oxidized iron
    • Abundant if other sediments absent
  7. What are examples of Biogenous marine sediments and of what two organisms are they mainly of?
    • Hard remains of once-livingorganisms
    • Shells, bones, teeth
    • Macroscopic (large remains)
    • Microscopic (small remains)
    • Tiny shells or tests settlethrough water column
    • Biogenic ooze (30% or moretests)
    • Mainly algae and protozoans
  8. What are two examples of Silica in Biogenous sediments and what type of ooze do they produce?
    • Diatoms (algae)
    • Radiolarians (protozoans)
    • (Produces Siliceous Ooze).
  9. What are they main properties of Siliceous Ooze?
    • Seawater undersaturated with silica socontinually dissolves back into water
    • Siliceous ooze commonly associated with highbiologic productivity in surface ocean becauseonce buried, they don’t dissolve easily
  10. Give examples of Calcium carbonate in biogenous sediments (2 organisms)
    • Coccolithophores
    • Foraminifera(protozoans)
  11. What properties describe Foraminifera(protozoans) and what type of ooze do they produce?
    • Use external food
    • Calcareous ooze
  12. What are some characteristics of Coccolithophores(algae)?
    • Photosynthetic
    • Coccoliths (nanoplankton)
    • Rock chalk
    • May use plates assunshades
  13. What factors control the distribution of biogenous sediments?
    • Productivity
    • Destruction (dissolution)
    • Dilution
  14. Give examples of Carbonate deposits (2 examples)
    • Limestone
    • Stromatolites
  15. Describe the properties Limestone.
    • Lithified carbonatesediments
    • White Cliffs of Dover, England ishardened coccolithophore ooze
  16. What environment do Stromatolites experience and of what bacteria were they originated?
    • Warm, shallow ocean, high salinity
    • Cyanobacteria
  17. Calcareous ooze and the CCD? Describe warm water, shallow ocean and cool, deep oceans with respect to their saturation of calcium carbonate(s).
    • Warm, shallow ocean saturatedwith calcium carbonate
    • Cool, deep ocean undersaturatedwith calcium carbonate
  18. Lysocline
    depth at which asignificant amount of CaCO3 beginsto dissolve rapidly
  19. Calcite compensation depth (CCD) At what 'cline?
    • Below lysocline, depth where CaCO3readily dissolves
    • little calcareous ooze
    • Rate of supply = rate at which the shellsdissolve
  20. Minerals precipitate directly from seawater (Hydrogenous) Give examples (At least 4)
    • Manganese nodules
    • Phosphates
    • Carbonates
    • Metal sulfides
    • Small proportion of marine sediments
    • Distributed in diverse environments
  21. Describe characteristics of Phosphates, it's use and describe the areas it would most likely to be found.
    • Phosphorus-bearing apatite sedimentary rock
    • Occur beneath areas in surface ocean of veryhigh biological productivity
    • phosphatesreleased into interstitial water by decomposition
    • Economically useful: fertilizer
  22. Give examples of Carbonates (CaCO3) (At least 3)
    • Aragonite and calcite
    • Oolites
  23. Give examples of Cosmogenous marine sediments (At least 2)
    • Macroscopic meteordebris
    • Microscopic iron-nickel and silicate spherules
  24. Give examples of Microscopic iron-nickel and silicate spherules (2 examples)
    • Tektites
    • Space dust
  25. Usually mixture ofdifferent sediment types contain up to how much non-biogenic components?
    biogenicoozes can contain up to 70% non-biogeniccomponents
  26. Neritic sediments cover about _ of sea floor
  27. Pelagic sediments cover about _ of sea floor
  28. Distribution of neritic and pelagic marinesediments controlled by:
    • Proximity to sources of lithogenous sediments
    • Productivity of microscopic marine organisms
    • Depth of water
    • Sea floor features
  29. How sea floor sediments represent surface ocean conditions
    • Microscopic tests sink slowlyfrom surface ocean to sea floor(10-50 years)
    • Tests could be movedhorizontally
    • Most biogenous tests clumptogether in fecal pellets
  30. Marine sediments often representocean surface conditions  preservesrecord of past
    • Temperature
    • Nutrient supply
    • Abundance of marine life
    • Atmospheric winds
    • Ocean current patterns
    • Volcanic eruptions
    • Major extinction events
    • Changes in climate
    • Movement of tectonic plates
  31. How do researchers traditionally retrieve sediments?
    • Dredge
    • Gravity corer
    • Rotary drilling
    • Deep Sea Drilling Program
    • Ocean Drilling Program
    • Integrated Ocean Drilling Program
  32. Studies reveal support for which theories about the ocean?:
    • plate tectonics
    • drying of the Mediterranean Sea
    • global climate change