Flashcards
Sedimentation
Cards in this deck (23)
- 1How is sediment classified?Area of deposition
Source and mode of transport
Grain size - 2The bigger the particle size...The faster the sinking rate
- 3—Hjulström’s diagram
- 4Lithogenous/Terrestrial SedimentFine, coarse grains produced by weathering and erosion of rocks on land (sand and mud)
- 5Biogenous SedimentFine and coarse grains derived from hard parts of organisms (typically shells and skeletal debris)
- 6Hydrogenous SedimentParticles precipitated by chemical or biochemical processes in seawater near the seafloor
- 7Volcagenous SedimentParticles ejected from volcanoes
- 8Cosmogenous SedimentVery tiny grains that originate from outer space (usually mixed with terrigenous and biogenic sediment)
- 9Ice Rafting (Lithogenous)Glacial marine sediments released by the gradual melting of icebergs
- 10Eolin Dust Deposits (Lithogenous)Wind-born sediment from the Sahara - red clay (iron) important for pelagic environment
- 11Ferromanganese nodules (Hydrogenous)Very slow layer growth (1-10mm every 1 million years) around growth triggering nuclei e.g. sand grains, mineral grains and biogenous material)
- found in deep water basins particularly on top of red clay - 12Calcareous Sediment (Biogenic)Made from:
Cocolithophores (planktonic algae)
Foraminiferas (zooplankton)
Pteropods (planktonic snails) - 13Siliceous Sediment (Biogenic)Mostly Opal from:
Diatoms (planktonic algae)
Radiolarians (protozoa, zooplankton) - warmer waters - 14Biogenic OozesSediments that are more than 30% biogenic
- 15Calcium Carbonate Depth (CCD)The ocean level below which the preservation of CaCO3 shells in surface sediments is insignificant - controlled by solubility of water which increases with depth due to increasing CO2 from dissolving CaCO3
- 16Siliceous Sediment (opal) Distribution controlled by:Sedimentation Rate: light, temperature, and nutrients affected by biological surface production
Solubility: oceans under-saturated in opal as has high dissolution rate (80% dissolved before reaching sediment) - 17Turbidity CurrentsFast flowing movements of sediment-water (sludge)
Triggered by sediment slumps at upper surface (e.g. earthquakes) - 18Turbidite DepositsSediment deposited when turbidity currents slow down on continental rise
- 19Turbidite bedsCaused by the sediment deposits from turbidity currents
Sediment dropped according to particle size - largest first - producing a graded bedding
- 20The Grand Banks Earthquake1929
A tsunami that interrupted several transatlantic phone lines
Speed worked out from time/distance of the cable breaks - 21The Storegga Slide6,100BC
Massive sediment slump off Norway
Collapse of continental slope built up over last ice age - 22Sedimentation Rates of: Estuaries Quiet Bays Continental Shelf and Slope Deep OceanEstuaries - up to several Ma
Quiet Bays - 0.5cm per Ma (due to low current velocities)
Shelf/Slope - 10-40cm every 1000a (currents)
Deep ocean - 1-5cm every 1000a (biogenic oozes) - 23—
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- MST1103 Flashcards on Sedimentation, created by Phoebe Drennan on 28/05/2017.
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- Phoebe Drennan
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