slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Study Guide available! Web site (dusk2.geo.orst.edu/oceans) Go to the syllabus page and click on the Study Guide for Tes PowerPoint Presentation
Download Presentation
Study Guide available! Web site (dusk2.geo.orst.edu/oceans) Go to the syllabus page and click on the Study Guide for Tes

Loading in 2 Seconds...

play fullscreen
1 / 31

Study Guide available! Web site (dusk2.geo.orst.edu/oceans) Go to the syllabus page and click on the Study Guide for Tes - PowerPoint PPT Presentation


  • 79 Views
  • Uploaded on

Study Guide available! Web site (dusk2.geo.orst.edu/oceans) Go to the syllabus page and click on the Study Guide for Test#1. Lecture 9: Marine Sediments. What’s all that muck at the bottom of the ocean, and what’s it good for?. Marine Sediments are:.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Study Guide available! Web site (dusk2.geo.orst.edu/oceans) Go to the syllabus page and click on the Study Guide for Tes' - lynn


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1
Study Guide available!Web site (dusk2.geo.orst.edu/oceans)Go to the syllabus page and click on the Study Guide for Test#1
lecture 9 marine sediments

Lecture 9: Marine Sediments

What’s all that muck at the bottom of the ocean, and what’s it good for?

marine sediments are
Marine Sediments are:
  • Particles of various sizes derived from a variety of sources that are deposited on the ocean floor
  • A vast “library” recording geologic, oceanographic and climatic conditions
  • Remarkably complete compared to land
where do these come from
Where do these come from?
  • Inputs are:-- rivers-- atmosphere-- surface waters-- volcanoes (both on land and submarine) -- deep ocean water-- outer space
classifications
Classifications
  • By SizeClay -- Silt -- Sand -- Pebble -- Cobble 0.001 mm 1 mm 100 mm
  • Effects of water velocity on transport: rivers and near-shore vs open ocean
sediment transport
Sediment Transport
  • Fluid velocitydetermines thesize of theparticles thatcan be moved
classifications1
Classifications
  • By OriginBiogenousTerrigenousHydrogenousCosmogenous
terrigenous sediments from land
Terrigenous sediments (from land)
  • Rivers
  • Winds (eolian)
  • Glaciers (ice-rafted debris, IRD)
  • Turbidites
  • Sea level changes
turbidites
Turbidites
  • Rapidly-accumulated terrestrial sediments
  • Earthquake-triggered submarine avalanches
  • High velocity (~50 mph!), erosive events
  • Good examples preserved on Mary’s Peak
biogenous sediments from living things
Biogenous sediments (from living things)
  • Calcareous (CaCO3)Foraminifera -- animalsCoccolithophores -- plants
  • Siliceous (SiO2)Radiolaria -- animalsDiatoms -- plants
productivity skeletons and soft tissue
Productivity = skeletons and soft tissue
  • Accumulation depends on production and preservation
  • SiO2 is preserved everywhere
  • CaCO3 is variable, depending on P, T, pH
c arbonate c ompensation d epth
Carbonate Compensation Depth
  • The depth at which carbonate input from the surface waters is balanced by dissolution in corrosive deep waters
  • In today’s ocean this depth (CCD) varies between 3 km (polar) and 5 km (tropical)
  • Thus, accumulation rates vary a lot!
accumulation rates for oozes
Accumulation Rates for Oozes
  • Productivity
    • reproduction of planktonic organisms
  • Preservation
    • silica dissolves only very slowly
    • calcium carbonate varies with depth
  • Ratesare variable: <1 to 15mm/1000 yr
slide24

Coastal waters are often highly productive, with abundant planktonic organisms thriving in the surface waters. Why then are biogenous oozes rarely found nearshore??

  • Do biogenous sediments dissolve readily at shallow depths on the continental shelf? NO
  • Do plankton species in coastal waters lack skeletons? NO
  • Are planktonic organisms consumed by large organisms, preventing deposition of skeletons? NO
slide25
the large input of terrigenous sediment to the continental margin overwhelms the biogenous component in the sediment. YES
hydrogenous from sea water
Hydrogenous (from sea water)
  • Metalliferous sediments at spreading ridges
  • Manganese nodules
  • Evaporites -- Salt deposits
cosmogenous from outer space
Cosmogenous (from outer space)
  • Meteorites and comets