OCE TEST 2
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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)
How are Neritic sediments distributed and in which regions are they normally found?
- Shallow water deposits
- Close to land
- Dominantly lithogenous
- Typically depositedquickly
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
How are Pelagic sediments distributed and in which regions are they normally found?
- Deeper water deposits
- Finer-grained sediments
- Deposited slowly
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
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
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
What are two examples of Silica in Biogenous sediments and what type of ooze do they produce?
- Diatoms (algae)
- Radiolarians (protozoans)
- (Produces Siliceous Ooze).
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
Give examples of Calcium carbonate in biogenous sediments (2 organisms)
What properties describe Foraminifera(protozoans) and what type of ooze do they produce?
- Use external food
- Calcareous ooze
What are some characteristics of Coccolithophores(algae)?
- Coccoliths (nanoplankton)
- Rock chalk
- May use plates assunshades
What factors control the distribution of biogenous sediments?
- Destruction (dissolution)
Give examples of Carbonate deposits (2 examples)
Describe the properties Limestone.
- Lithified carbonatesediments
- White Cliffs of Dover, England ishardened coccolithophore ooze
What environment do Stromatolites experience and of what bacteria were they originated?
- Warm, shallow ocean, high salinity
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
depth at which asignificant amount of CaCO3 beginsto dissolve rapidly
Calcite compensation depth (CCD) At what 'cline?
- Below lysocline, depth where CaCO3readily dissolves
- little calcareous ooze
- Rate of supply = rate at which the shellsdissolve
Minerals precipitate directly from seawater (Hydrogenous) Give examples (At least 4)
- Manganese nodules
- Metal sulfides
- Small proportion of marine sediments
- Distributed in diverse environments
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
Give examples of Carbonates (CaCO3) (At least 3)
- Aragonite and calcite
Give examples of Cosmogenous marine sediments (At least 2)
- Macroscopic meteordebris
- Microscopic iron-nickel and silicate spherules
Give examples of Microscopic iron-nickel and silicate spherules (2 examples)
Usually mixture ofdifferent sediment types contain up to how much non-biogenic components?
biogenicoozes can contain up to 70% non-biogeniccomponents
Neritic sediments cover about _ of sea floor
Pelagic sediments cover about _ of sea floor
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
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
Marine sediments often representocean surface conditions preservesrecord of past
- Nutrient supply
- Abundance of marine life
- Atmospheric winds
- Ocean current patterns
- Volcanic eruptions
- Major extinction events
- Changes in climate
- Movement of tectonic plates
How do researchers traditionally retrieve sediments?
- Gravity corer
- Rotary drilling
- Deep Sea Drilling Program
- Ocean Drilling Program
- Integrated Ocean Drilling Program
Studies reveal support for which theories about the ocean?:
- plate tectonics
- drying of the Mediterranean Sea
- global climate change
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