1. Chapter 14: Sediments
Oceanography 2014

2. Vocabulary Stratigraphy Evaporites Terrigenous Sediments (Lithogenous)
Cosmogenous Sediments
Diatomaceous Earth
Biogenous Sediments
Grain Size
Calcareous Ooze
Mud
Siliceous Ooze
Well Sorted Sediment
Hydrogenous Sediments

3. Root Words
Terra-
Hydro-
Bio-
Cosmo-

4. Sedimentation Sedimentation: the accumulation of sediments
Weathering: process of breaking down rocks to create sediments
Erosion: movement of sediments by wind, gravity, or water

5. Sediment Classification
Sediments are classified by grain size and origin
Grain Size:
from largest (coarse) to smallest (fine) is gravel, sand, silt, and clay
Mud = silt + clay
Loam = sand + silt + clay
Origin:
land, organisms, chemicals, volcanoes, and space (see table)
Poorly sorted sediment: sample contains a mixture of sediment sizes.
Well sorted sediment: sample contains similar or same sized particles.

6. Origin of Sediments Type Origin Composition Location Terrigenous
From land by rivers, glaciers, & wind
Quartz and feldspar
(sand and mud)
Rivers: temperate regions
All: continental shelves
Biogenous
Organisms, Shells, & skeletons
Carbon based; calcium-type (calcareous ooze) and silicon-type (siliceous ooze)
Tropical continental shelves and deep sea
Hydrogenous
Chemicals including biochemicals
Ferromanganese nodules; phosphorites (organic debris from upwelling)
Deep sea deposits; continental shelves
Volcanogenic
Volcanic eruptions
Cosmogenic
Particles that fall from space

7. Sediment Classifications
Grain Size
Example
Clay
<0.004 mm
Talc, dusty powder
Silt
0.004 – mm
Heavy powder
Sand
– 2 mm
Sugar crystals
Granule
2 – 4 mm
Aquarium gravel
Pebble
4 – 64 mm
Grape-sized
Cobble
64 – 256 mm
Orange-sized
Boulder
256 mm +++
Brick or larger

8. Where do sediments come from?
Rivers
Glaciers
Waves
Winds
Dissolving pieces of living things (biogenous)
Chemical reactions

9. Terrigenous Sediments
Most abundant sediment
45% of all ocean sediment
Found at continental margins, abyssal plains and polar areas
River deposition:
Atlantic Ocean: Amazon River
Pacific Ocean: very little river deposition
Wind deposition:
Dust blown across deserts
Sahara Desert – Atlantic Ocean
Gobi Desert – Pacific Ocean

11. What do you see here?

12. What do you see here?

13. Biogenic Sediment Second most abundant Found in deep ocean basins
Most common throughout the ocean
Found in deep ocean basins
Depends on biological productivity and rate of decomposition
Hard parts of organism preserved
Calcareous
Siliceous

14. Biogenic Sediment: Oozes
Calcareous Ooze
Formed from the shells of pteropods, forminifera and coccolithophores
Siliceous Ooze
Diatoms

15. Hydrogenous Sediment Low abundance
1% of all ocean sediment
Formed from dissolved solids precipitating out of seawater
Most common: manganese nodules
composed of layers of metals such as manganese, iron, nickel, cobalt, and copper

16. Cosmogenic Sediment Least abundant Sediment
Sources include interplanetary dust, meteorites, asteroids, and comets

18. Distribution of Sediments

21. Hjulstrom’s Diagram
Displays the relationship between particle size and energy for erosion, transportation and deposition.

22. Sedimentation at Continental Margins
Continental Shelf, Slope and Rise
Controlled by tides, waves and currents
Main type of sediment found: Terrigenous and Biogenous
How is it getting to these areas?
River Deposition (large particles)
Currents Moving Sediment(sand and large particles)
Waves Moving Sediment(silt and clay)
How fast can it accumulate?
Depends on area
Ranges from 10 centimeters to 7 meters per year
Important note about the Atlantic coast: much of the sediment is trapped by estuaries and does not reach the ocean.

23. Shelf Sediment Type by Region
Calcareous biogenic sediments dominate tropical shelves.
River-supplied sands and muds dominate temperate shelves.
Glacial till and ice-rafted sediments dominate polar shelves.

24. Sedimentation at Deep Ocean Basins
Main type of sediment found: Terrigenous, Biogenous, and Hydrogenous
Sediments Found:
Manganese Nodules (hydrogenous)
Turbidites (terrigenous)
Clays (terrigenous)
Cover 31% of deep ocean
Accumulation: 2 mm/ 1000 years
Oozes (biogenic)
Accumulation: 1-6cm/ 1000 year

26. Studying Sediments Tools and Techniques: Clam-Shell “Grab” Samplers
Piston Corers
Deep-Sea Drilling
Seismic Profiling
Grab samplers take a “bite” out of the sediment covering the bottom.

27. Corers use a weight to drive a core barrel into a soft bottom.

29. Why are Sediments Important?
Economics
1/3 of oil and gas reserves are on the continental margins
Sand and Gravel from ocean sources are a $480 million industry
Medicines
Microbes living in ocean sediment have been used to make antibiotics
In 2003, a group of bacteria was found within ocean sediment that could be used to make a medicine to treat cancer

30. What are sediments? Where do they come from?
Oceanography March 19, 2014
What are sediments? Where do they come from?

32. Sediment Classification
Oceanography March 21, 2014
Sediment Classification
Name two ways sediments can be classified.
What does “bio” mean? How does that relate to a type of marine sediment?

33. Oceanography March 20, 2014
Sediment Types
What role does weathering and erosion play on the introduction of sediments to the ocean?
Speculate on why you think cosmogenic sediments would be the least common.

34. Why would scientists want to collect samples of oceanic sediment?
Oceanography March 28, 2014
Sediment Sampling
Why would scientists want to collect samples of oceanic sediment?
What are two types of information that could be determined from a sample of ocean sediment.
Name two ways sediment can be sampled.

35. What are the two types of biogenic sediment? How do they form?
Oceanography March 20, 2014
Biogenic Sediments
What are the two types of biogenic sediment?
How do they form?
Hjulstrom’s Diagram

36. Sedimentation Factors
Oceanography March 20, 2014
Sedimentation Factors
What does a Hjulstrom’s Diagram explain?

37. Oceanography March 20, 2014 Continental Sedimentation What factors control sedimentation at continental margins?