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"Red Clay" -- fine terrigenous dust + volcanic ash Settles eventually, everywhere

LITHOGENOUS SEDIMENT- Pelagic. "Red Clay" -- fine terrigenous dust + volcanic ash Settles eventually, everywhere Dominant only where other types absent. Class #12. OCEAN SEDIMENTS Cosmogenous Biogenous Hydrogenous. OCEAN SEDIMENTS Sources (origins) Distribution TYPES (BY SOURCE):

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"Red Clay" -- fine terrigenous dust + volcanic ash Settles eventually, everywhere

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  1. LITHOGENOUS SEDIMENT- Pelagic • "Red Clay" -- fine terrigenous dust + volcanic ash • Settles eventually, everywhere • Dominant only where other types absent

  2. Class #12 OCEAN SEDIMENTS Cosmogenous Biogenous Hydrogenous

  3. OCEAN SEDIMENTS • Sources (origins) • Distribution • TYPES (BY SOURCE): • Lithogenous ("rock-derived') • Biogenous ("life-derived") • Hydrogenous ("water-derived") • Cosmogenous ("cosmic-derived")

  4. Sediment Types

  5. COSMOGENOUS SEDIMENTS • Micro-meteorites • silicates, iron metals • very small quantities (noticeable in red clay)

  6. Sediment Types

  7. BIOGENOUS SEDIMENTS -- produced directly by living organisms • Large fragments: warm, shallow areas • clams, corals • Very thick accumulations in some places

  8. 2) Everywhere: Tiny particles produced... • Pelagic sediment • Shells or skeletons of microplankton • Biogenous "oozes” (>30% biogenous material) • Calcareous ooze • CaCO3 = calcium carbonate • Siliceous ooze • SiO2 = silica (+ H2O)

  9. Calcareous ooze: Coccoliths + Foraminifers

  10. Siliceous ooze: Diatoms and/or Radiolarians

  11. Single –celled organisms that make tiny shells/skeletons that settle to the ocean bottom (biogenous seds).

  12. Where do we find biogenous oozes? • 1. Siliceous oozes • Controlled by nutrients: High Si, N, P, and Fe causes high productivity; upwelling zones • 2. Calcareous particles- almost everywhere, but in some places they are dissolved before they get to the bottom

  13. Where do we find biogenous oozes?- MORE • 2. CaCO3 particles dissolve quickly below the “Carbonate Compensation Depth” (CCD) • Atlantic: ~ 4,000 m depth • Pacific: ~ 500 - 1,500 m depth • SiO2 particles dissolved more slowly (everywhere) • Siliceous ooze can collect in deep areas • But…Must accumulate quickly- high productivity areas • 3. NOT dominant near continents, usually: • Too much terrigenous sediment

  14. Sediment Types

  15. CaCO3 is very important chemically

  16. HYDROGENEOUS SEDIMENTS: precipitation of dissolved elements in water • Evaporites • Evaporation in isolated basins • E.g., Mediterranean Sea 6 M.Y. ago • Precipitation of "salts" • NaCl (halite) • CaSO4• 2H2O (gypsum)

  17. Salt Mine under Detroit: Shallow sea over 400 m.y. ago

  18. 2. Manganese nodules and crusts • Mn + Fe oxides (+ Cu, Co, Ni) • In deep ocean basins and along mid-ocean ridges • Origin: -- chemical reaction between oxygen in water and dissolved Mn +Fe • Mn + Fe come mostly from sediments and hydrothermal vents

  19. 3) Phosphate minerals • P released when organic matter degrades- Minerals precipitated • On Cont. shelves • 4) Metal sulfides from hydrothermal vents • Collect on ocean floor • Metal-rich (gold, copper)

  20. Fig. 4.18

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