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

OCEAN SEDIMENTS Cosmogenous Biogenous Hydrogenous Class #12 OCEAN SEDIMENTS Cosmogenous Biogenous Hydrogenous

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

Sediment Types

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

Sediment Types

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

CaCO3 = calcium carbonate 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)

Calcareous ooze: Coccoliths + Foraminifers

Siliceous ooze: Diatoms and/or Radiolarians

Single –celled organisms that make tiny shells/skeletons that settle to the ocean bottom (biogenous seds). Material Produced Algae Protozoans CaCO3 Coccolithophores Foraminifera SiO2 Diatoms Radiolarians

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

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

Sediment Types

CaCO3 is very important chemically

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)

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

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

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)

Fig. 4.18