O Lecture 10/15/10
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Where do sediments come from?
space, eriosion, weather
What are marine sediments
- eroded rock particles and fragments
- transported to ocean
- deposit by settling through water column
- oceanographers decipher earths history through studying sediments
What the two types of weather
- Physical weather
- chemical weather
breakdown of rocks, soils, and minerals through direct contact with the planet's atmosphere
Some components of physical weathering
heat, water, ice, and pressure
What is physical weathering?
- physical breakdown of rock
- makes small chunks and higher surface area
some components of chemical weathering
soil pH, temperature, precipitation, composition of rock
Trees help chemical weathering
H2O + CO2 -> Ca2+ + 2HCO3-
What are the two types of chemical weathering?
Congruent Chemical weathering
results in only dissolved ions
Incongruent Chemical Weathering
results in newly made clay minerals and dissolved ions
Example of congruent chemical weathering
- limestone weathering
- CaCO3 + H2O + CO2 -> Ca2+ +2HCO3-
Example of Incongruent weathering
2NaAlSi3O8 + 11H2O + 2CO2 -> 2Na+ + 2HCO3- + 4H4SiO4 + Al2Si2O5(OH)4
What is the size of particulate matter?
larger than .45 microns
What is the size of dissolved matter?
below .45 microns
How is marine sediment classified?
What are the classifications of marine sediment?
- Terrigenous or ithgenous
- Hydrogenous (aka Authigenic)
Cosmogenous Marine Sediment
- macroscopic meteor debris
- overall insignificant proportion of marine sediment
Hydrogenous Marine Sediment
near hydrothermal vents, lots of metal ions are released intot he water and these ions oxidize or combine with silica and precipitate out as dark, metal rich sediment
Volcanogenous marine sediment
- comes from volcanoes
- distributed in the marine realm by wind, streams, submarine gravity
- most lithogenous sediments at continental margins
- coarser sediments closer to shore
- finer sediments farther from shore
- mainly mineral quartz
- erroded rock fragments from land
- agents of transport - water, wind, ice, gravity
wind as an agent of transport
Biogenous marine sediments
- hard remains of once-living organisms
30% more or more tests
factors controlling distribution of biogenous sedimetns
- destruction (dissolution)
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