1. Sediments

2. What to Watch for? You will see the true face of the ocean floor
Covered by sediments, gravel, silt and mud
Sediment particles from land, from biological activity, and even from space
Sediments can help us define what occurred in recent history in the ocean basin
Sediment thickest at continental margins
Thinnest over active oceanic ridges
Sedimentary “memory” of ocean basin is short
Think about
Movement, transport, how did the sediment arrive, where did it come from, and how can we tell the story of the ocean basin
Think about daily contact with marine sediment
Building materials, pool filters, toothpaste, oil, natural gas, paint

3. Sediment
Particles of organic or inorganic matter that accumulates in a loose, unconsolidated form.

4. Major Sediment Input to the Oceans
Source
Estimated Amount (109 tons/yr)
Rivers
18.3
Glaciers and ice sheets
2.0
Wind blown dust
0.6
Coastal erosion
0.25
Volcanic debris
0.15
Groundwater
<0.48

5. What do sediments look like?
Depends where you are
Atlantic ridge
Sponges and corals may be growing over the dusting of sediment
Smooth ocean floor
Brittle stars feed off surface bacteria and fallen particles of organic sediment
May see ripples if the bottom has swift currents
Colors differ
Biological
Often white or cream colored
Silica deposits
Often gray
Clays on the ocean floor
Red due to oxidation
Chocolate brown

6. Sediment Classifications
Origin
Size
Gravel - Bigger than 2 mm
Sand – .062 – 2 mm, Big in Ocean Terms
Silt – mm, Gritty on Teeth
Clay - <.004 mm
Use Size to Determine the Energy of the Environment
Well sorted sediments
Sediments mixture that contains sediments of one size
Poorly sorted sediments
Sediments mixtures that contains a variety of of sizes

7. Gravel Sand Mud (silt & clay) Sediment Type Diameter (mm) Boulder
>256
Cobble
65-256
Pebble
4-64
Granule
2-4
Sand
Very coarse
1-2
Coarse
0.5-1
Medium
Fine
Very fine
Mud (silt & clay)

8. Deep Sea Sedimentation
The Deep sea has two main sources of sediment:
External- terrigenous material transported to oceans via rivers and wind
Internal-biogenic and authigenic from the sea.

9. Origin of the Particles (Genetic)
Proposed by Sir John Murray and A.F. Renard while studying sediments during the Challenger expedition
Terrigenous/Lithogenous – terra = Earth, generare = to produce
From Earth
Biogenous – Bio = life, generare = to produce
From life
Zebra Muscles
Diatoms
Hydrogenous/ Authigenic – Hydro = life, generare = to produce
Precipitates chemically from sea water
Iron Stains in Sink in regular water
Cosmosgenous – cosmos = universe, generare = to produce
Comes from Outer Space
Micro meteorites

10. Origin Classification
Terrigenous: Sands and mud produced by weathering and erosion of rocks on land.
Biogenic: CaCO3 (calcium carbonate) and SiO2 (silica) muds and oozes composed of hard parts of organisms.
Authigenic: formed by precipitation of minerals in seawater (Manganese (Mn) and Phosphorus (P) nodules).
Volcanogenic: ejected from volcanoes (ash).
Cosmogenous: pieces of meteorites that survive trip thru atmosphere.

11. Terrigenous Particles
Coming from islands or nearby continents
Most abundant = Granite
Sources of quartz and clay in the oceans
Earth’s crust is made of minerals
Inorganic crystalline materials that have a specific chemical composition
Both particles are small enough that they get transported to deep ocean floor
Transportation?? How did they get there what was the Transport Agent…
Rivers – Clay  Sand
Mississippi River Delta: Birds Foot
Trapped Near the Continents

14. How sediments reach deep ocean
Turbidity Currents
Density and Gravity pull particles down Slope
Causes flatness of the abyssal plains
Resistant sandstone - rubble
Turbidity current deposit rubble

16. Terrigenous Particles
Wind (Eolian)
Covers Long Distances
Small Grain Sizes
Slow Accumulation

17. Sediments that wind transports from the Sahara Desert
Africa's West Coast:
Sediments that wind transports from the Sahara Desert

19. Terrigenous Particles
Transportation
Glaciers
Deposits of sediment only happens when glaciers reach sea level
Iceberg Rafting
Rivers and streams
Eloation

20. Biogenous Particles 2nd Most abundant source for sediments
Coccolithophorid
2nd Most abundant source for sediments
Skeletal Components
Sediment Rich in skeletal material “ooze”
Sample must contain more than 30% biogenic material
Two Major Players
CaCO3 Calcium Carbonate: Plants
Foraminifera: Animals
To make an “ooze”
Production ~ Same everywhere
Preservation ~ More soluble at high pressure and low temperature
As it sinks carbonate needs shallower waters ~ 3500 – 4500 m starts to dissolve
When carbonate no longer can be preserved = CCD carbonate compensation depth
Little Dilution – Rapid input of Something else
Get away from terrigenous areas
Foraminifera

21. Foraminifera (zooplankton with CaCO3 shell)

22. White Cliffs of Dover

23. Biogenous Particles Silica Opal – SiO2 . n H2O Radiolarians
Zooplankton
Diatoms – Plants
Radiolarians
To make a Siliceous “ooze”
Production ~ High Productivity Zones they Do Well
Preservation ~ Entire Ocean is Under saturated with Silica
Once animal dies it starts to be dissolved
Preservation takes place with over whelming the system
Make a lot so a Few can Survive
Getting to the sediment is the key
Micro environment once diatom reaches sediment won’t dissolve because others already have been and water is saturated with silica

24. Diatoms (phytoplankton with SiO2 shell)

25. Cleaning agents and toothpaste often contain diatoms because of their sharp surfaces

27. Biogenous Sediments Soft Tissue Gas Hydrates Near continental Margins
A lot of methane stored in sediments
Might be a useful source of fuel
Possible Problems
Limited Stability Range
Methane is much greater green house gas = AGGRESSIVE
Large Gaseous Emissions!

31. Hydrogenous/Authigenic Sediments
Formed by chemical or biochemical reactions on ocean floor/ formed in the place they now occupy
Nodules of ferromanganese (Fe and Mn) or phosphorite (P).
Mn found deep sea beds
P found continental margins
Concentric layers of metal oxides accrete on particles over millions of years (1-4 mm per 106 y).
Contain economically important metals Cu, Zn, Co and Pb. (but too expensive to harvest).
Origin uncertain (biological?)

32. Ferromanganese nodules
Floor of South Pacific Ocean.
Nodule size 1-5 cm diameter

33. Ferromanganese nodules
Cross-section

34. Hydrogenous Pebble like
Manganese Nodules
mm per million years, they grow slow
Evaporites – Hydrogenous deposit, precipitates out as water evaporates
Salts: Evaporates from isolated arms of the ocean
Sea salts
Red sea
Persian Gulf
Gypsum
Oolite sands – Calcium carbonate precipitates from shell fragments, white and rounded
Abundant in many warm, shallow waters
Bahamas

36. Deep Sea Sedimentation Process

37. Distribution of Sea Sediments
Neritic sediments: consist of primary terrigenous material
Found normally along continental shelf's

38. Distribution of Deep Sea Sediments
Pelagic sedimentation: Sediments of the slope, rise, and deep-ocean that originate in the ocean
Pelagic:
Inorganic red or brown clays and silt
Fine-grained ( – mm)
Dominate below waters with little planktonic production.

39. Deep Sea Sedimentation
Pelagic:
Oozes
Deep ocean sediment that has at least 30% of debris from planktonic organisms
Named after the dominate remnant organism
Calcareous oozes (CaCO3)
Shells of foraminifera & pteropods (zooplankton) and coccolithophorids (phytoplankton).
Accumulate on seafloor above CCD.
Forms hard limestone under pressure
Siliceous oozes (SiO2)
Shells of radiolaria (zooplankton) and diatoms (phytoplankton).
Accumulate on seafloor below CCD.
Accumulate below regions of high diatom production (equator, poles, upwelling areas)

42. Deep Sea Sedimentation Distribution
TYPE
COMPO-SITION
ATLANTIC (%)
PACIFIC (%)
INDIAN (%)
GLOBAL (%)
Foram. ooze
Carbonate 65 36 54 47
Pteropod ooze 2
0.1 -
0.5
Diatom ooze
Silica 7 10 20 12
Radiolarian ooze 5 3
Red clay
Aluminum silicate 26 49 25 38

43. Atlantic Basin Sediments as thick as 1 km (3,300 feet) Small area
Great numbers of rivers spilling sediments into ocean

44. The Atlantic basin contains a “two-layer-cake” stratigraphy–a thick basal layer of carbonate ooze overlain by a layer of mud.

45. Pacific Basin Less than .5 km in thickness Large area
Pacific has many trenches that the sediment gets trapped

46. Pacific plate moves across latitudes…

47. The Pacific basin contains a “five-layer-cake” stratigraphy, because unlike the Atlantic its sea floor as it spreads crosses the equator where the CCD is lowered to the ocean bottom.

48. Continental Margins
Rivers and Erosion allow for a lot of the terrigenous sediment transported to the margins
Orderly sorting of particles from finest to large grains
Large grains stay near shore
Small grains get carried into the deep ocean
Biogenous Sediments also accumulate in this region
Productivity of near shore waters is normally high
Some sediments are lithified due to the pressure of overlying sediments.

49. Exceptions
Shelf deposits are subject to erosion as the sea level fluctuates.
Ice ages
Exposed shelf leads to further erosion

50. Studying Sediments
Clamshell sampler - Shallow sediment sampler

51. Piston Corer
Device capable of punching through as much as 25 m of sediment and returning an intact plug of material

52. Scientist Sample Sediments

53. Coring Preserves deep Straitigraphy, or Layering

54. Stratigraphy
Analysis of layered sedimentary deposits in the ocean (or on land)
Paleo-oceanogrpahy- Study of the Ocean’s past
Interpret ocean and climate history from evidence in deep-sea sediments
Started in 1930’s

55. Andrill

57. JOIDES: Deep-Sea Drilling Program (DSDP)
1978
Drills into the ocean floor to take core samples
24 a day
50 scientists
65 crew people
Statistics

58. Economic Importance
Taken from sedimentary deposits of continental shelves and rises
36% of the world’s crude oil
28% of its natural gas
125 billion dollars
Sand and gravel estimated over 480 million dollars

59. Chapter 5 Vocabulary
Silt- Sediment particle between and mm in diameter
Sand- Sediment particle between and 2 mm in diameter.
Clay- Sediment particle smaller than mm in diameter the smallest sediment size category.
Well-sorted sediments- A sediment in which particles are of uniform size.
Poorly-sorted sediments- A sediment in which particles of many sizes are found.
Terrigenous Sediments- Sediment derived form the land and transported to the ocean by wind and flowing water

60. Biogenous Sediments- Sediment of biological origin
Biogenous Sediments- Sediment of biological origin. Organisms can deposit calcareous (calcium-containing) or siliceous (silicon-containing) residue.
Hydrogenous Sediments- A sediment formed directly by precipitation from seawater; also called authigenic sediment.
Authigenic sediments- Sediment formed directly by precipitiaon from seawater; also called hydrogenous sediment.
Cosmogenous sediments- Sediment of extraterrestrial origin.
Microtektites- Translucent oblong particles of glass, a component of cosmosgenous sediment.
Neritic sediments- Continental shelf sediment consisting primary of terrigenous material.
Pelagic sediments- Sediments of the slope, rise, and deep-ocean floor that originate in the ocean.

61. Turbidites- A terrigenous sediment deposited by a turbidity current; typically, coarse-grained layers of nearshore origin interleaved with finer sediments.
Siliceous Ooze- Ooze composed mostly of the hard remains of silica-containing organisms.
Calcareous Ooze- Ooze composed mostly of the hard remains of organisms containing calcium carbonate.
Foraminifera- One of a group of planktonic amoeba-like animals with a calcareous shell, which contributes to biogenous sediment.
Pteropods- A small planktonic mollusk with a calcareous shell, which contributes to biogenous sediments.

62. Radiolarian- One of a group of usually planktonic amoeba-like animals with a siliceous shell, which contributes to biogenous sediments.
Diatoms- Earth’s most abundant, successful, and efficient single celled phytoplankton. Diatoms possess two interlocking valves made primarily of silica. The valves contribute to biogenous sediments.
Nodule- Solid mass of hydrogenous sediment, most commonly manganese or ferromanganese nodules and phosphorite nodules.
Evaporite- Deposit formed by the evaporation of ocean water.
Oolite sands- Hydrogenous sediment formed when calcium carbonate precipitates from warmed seawater as pH rises, forming rounded grains around a shell fragment or other particle.

63. Piston Corer- A seabed-sampling device capable of punching through up to 25 m (80 feet) of sediment and returning an intact plug of material
Stratigraphy- The branch of geology that deals with the definitions and description of natural divisions of rocks; specifically, the analysis of rock strata.
Paleoceanography- The study of the ocean’s past.
Coccolithophores- A very small planktonic alga carrying discs of calcium carbonate, which contributes to biogenous sediment.
Calcium Carbonate Compensation Depth (CCD)- The depth at which rate of accumulation of calcareous sediments equals the rate of dissolution of these sediments. Below this depth, sediment contains little or no calcium carbonate.

64. Clam shell sampler- A sampling device used to take shallow samples of the ocean bottom.
Minerals- A naturally occurring inorganic crystalline material with a specific chemical composition and structure.
Lithification- Conversion of sediment into sedimentary rock by pressure or by the introduction of a mineral cement.

65. Homework with in Chapter 5 - Book
Read Chapter 5 take notes
Make flashcards of vocab terms
Pg. 142 Review Questions – 1, 2, 3
Pg. 142 Critical Thinking Questions – 1, 2