1 / 22

Sediments

Sediments. Memory of the Ocean (Read Chapter 5). Classification by Particle Size. Table 5.1 (p.118) Ocean sediments usually sand, silt, and clay Smaller sediments Smaller particles easier to move. Classification by Particle Size. Well-Sorted Sediments

lesley
Download Presentation

Sediments

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Sediments Memory of the Ocean (Read Chapter 5)

  2. Classification by Particle Size • Table 5.1 (p.118) • Ocean sediments usually sand, silt, and clay • Smaller sediments • Smaller particles easier to move

  3. Classification by Particle Size • Well-Sorted Sediments • Sediments with only one size of particles • Narrow fluctuation of waves, tides, and currents • Poorly-Sorted Sediments • Sediments with particles that are a mixture of sizes • Large fluctuations of waves, tides, and currents

  4. Classification by Source • Terrigenous Sediments (most abundant) • Sediment that comes from land • Erosion, blown dust, volcanic eruptions • Travel by water and wind to ocean • Come from crystals of igneous rocks that cooled slowly • Ex: Sandstone, shale

  5. Classification by Source • Biogenous Sediments • Come from biological sources • Can be either calcareous (calcium-containing) or siliceous (silicon-containing) • Small plants and animals remove materials from water to make skeletons and shells that accumulate as sediment when the organisms die

  6. Biogenous Sediments (cont.) • Example: shell limestone

  7. Classification by Source • Hydrogenous Sediments • Minerals that come directly out of (precipitate from) seawater • Mineral sources • Ocean ridges • Submerged sediment and rock • Hydrothermal vents • River runoff • Also called authigenic sediments (authi- formed from that spot)

  8. Hydrogenous Sediments (con.t) • Examples: • Manganese and posphorite nodules • Rock salt

  9. Classification by Source • Cosmogenous Sediments • Come from beyond Earth (least common) • Sources • Interplanetary dust • Asteroid and comet impacts

  10. Cosmogenous Sediments (cont.) • Examples • Meteorite • Microtektites • Translucent, rain-drop shaped pieces of glass • Form from asteroid or comet impacts

  11. Sediment Distribution • Neritic Sediments • Sediments of continental shelf • Mostly terrigenous • Pelagic Sediments • Slope, rise, and deep ocean floor sediments • More biogenous sediments than neritic • Currents, wave action, and turbulence place large grain sediments near coast and small grain near shelf break

  12. Deep-Ocean Basin Sediments • Turbidites • Layers of terrigenous sand mixed with pelagic sediments • Deposited by turbidity currents • Clays • Formed by dust, volcanic ash, and microscopic waterborne particles

  13. Deep-Ocean Basin Sediments • Oozes • Sediment of the deep ocean that is at least 30% biogenous material • Named after the main organism remains found in the ooze

  14. Deep-Ocean Basin Sediments • Calcareous ooze • Calcium-rich sediment • Composed of: • Foraminifera (amoeba-like) • Pteropods (small drifting molecules) • Coccolithophores (tiny algae)

  15. Calcareous Ooze (cont.) • Calcium Carbonate Compensation Depth (CCD) • Specific depth where rate at which calcareous sediments contributed to the ocean floor equals the rate at which those sediments dissolve • Below this depth calcium carbonate skeletons dissolve, and no calcareous ooze builds up • About 4,500 meter deep

  16. Siliceous Ooze • Silicon-rich sediment • Found in colder areas and greater depth than calcareous ooze • Composed of: • Radiolarian (amoeba-like) • Diatoms (single-celled algae)

  17. Oozes (cont.) • Fossil material from these oozes are used in flat paint, tooth and car polishes, and pool and spa filters

  18. Deep-Ocean Basin Sediments • Hydrogenous sediments • Examples • Manganese nodules • Phosphorite nodules • Could be used in agricultural fertilizer

  19. Hydrogenous Sediments (cont.) • Hydrogenous Sediments • Evaporites • As water evaporates in landlocked seas, lakes, or isolated arms of the ocean, salt forms • Examples • Carbonates (limestone) • Calcium sulfate (Gypsum)

  20. Hydrogenous Sediment (cont.) • Hydrogenous Sediments • Oolite Sands • When pH rises in warmed seawater, calcium carbonate precipitates forming rounded grains (sand) around a shell fragment

  21. Hydrogenous Sediment (cont.) • Hydrogenous Sediments • Oolite Sands • When pH rises in warmed seawater, calcium carbonate precipitates forming rounded grains (sand) around a shell fragment

More Related