Chapter 14: Marine Sediments Chapter 14 notes… Do page 1 (questions) LAST *page 2: Sediment types (where do they come from) *page 3: Location: shelf vs. deep ocean

Chapter 14: Marine Sediments Fig. 5-23

Marine Sediments Fig. CO-4

Sediments reveal Earth history Sediments lithified Mineral composition Sedimentary texture Past climate Plate motions Age of seafloor Fossil evolution and extinction

Sediments classified by origin Lithogenous (Land) Biogenous (Life) Hydrogenous (Water) Cosmogenous (Space)

Lithogenous sediments Fig. 4.5

Lithogenous/ Terrogenous sediments Rock fragments from land Transported to oceans by Rivers Wind Ice Gravity flows (e.g. turbidity currents)

Rivers transport much sediment Fig. 5-5

Biogenous sediments Hard parts of once-living organisms Shells, teeth, bones Fig. 5-10

Biogenous marine sediments Commonly either calcium carbonate (CaCO3) or silica (SiO2 or SiO2·nH2O - opal) Usually planktonic (free-floating)

Biogenous sediments Calcareous ooze (CaCO3) Siliceous ooze (SiO2) Microscopic protozoans, foraminifera Microscopic algae, coccolithophores Siliceous ooze (SiO2) Microscopic protozoans, Radiolaria Microscopic algae, diatoms

Calcium carbonate in biogenous sediments Coccolithophores (algae) Photosynthetic Coccoliths (nano-plankton) Rock chalk Fig. 4.8a

Calcium carbonate in biogenous sediments Foraminifera (protozoans) Use external food Calcareous ooze Fig. 4.8c

Carbonate deposits Limestone (lithified carbonate sediments) Stromatolites Warm, shallow-ocean, high salinity Cyanobacteria Exist in hypersaline tidal pools – Hamelin Pool in Shark Bay, Australia and Eleuthra Bank, Bahamas Fig. 4.10a

Distribution of calcareous oozes in surface sediments of modern sea floor Fig. 4.14

Silica in biogenic sediments Diatoms (algae) Photosynthetic Diatomaceous earth Radiolarians (protozoans) Use external food Siliceous ooze Fig. 4.7a Fig. 4.7b

Siliceous ooze Seawater undersaturated with silica Fig. 4.11 Seawater undersaturated with silica Siliceous ooze commonly associated with high biologic productivity in surface ocean

Hydrogenous marine sediments Minerals precipitate directly from seawater Manganese nodules Evaporites Inorganic Carbonates Metal sulfides Small proportion of marine sediments Distributed in diverse environments

Manganese nodules Very low rate of accumulation Fig. 4.15a Manganese nodules Very low rate of accumulation Larger nodules grow larger faster Origin is unknown

Cosmogenous sediments Extraterrestrial fragments Extra = outside Terr = Earth ial = makes the word an adjective Glassy tektites Fe-Ni micrometeorites Found in deep ocean where other sediments accumulate very slowly

Meteorite impact K-T meteorite crater off Yucatan peninsula Tektites and spherules found in marine seds Shocked quartz in marine seds Fig. 5D

TO DO Finish remaining Ch. 14 Notes Sediments Analysis Prelab Lab next class! 