Introduction to Marine Science (G5405)

7/31/2019 Introduction to Marine Science (G5405)

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BASIC OCEANOGRAPHY

1Diploma in Idustrial Laboratory

Technology Yr 2,2009


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What is Oceanography

The scientific study of the ocean and itsinhabitants

Major Sub disciplines Marine geology & geophysics Chemical oceanography Physical oceanography Biological oceanography and marine

biology Ocean Engineering

Marine policy and laws 2

Diploma in Idustrial LaboratoryTechnology Yr 2,2009


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1. Physical Oceanography

or marine physics, studies the ocean's

physical attributes including temperature-salinitystructure, mixing, waves, internal waves, tides

and currents. Of particular interest is thebehaviour of sound (acoustical oceanography),

light (optical oceanography) and radio waves inthe ocean.

3Diploma in Idustrial LaboratoryTechnology Yr 2,2009
http://en.wikipedia.org/wiki/Ocean_surface_wavehttp://en.wikipedia.org/wiki/Tidehttp://en.wikipedia.org/wiki/Ocean_currenthttp://en.wikipedia.org/wiki/Acoustical_oceanographyhttp://en.wikipedia.org/wiki/Acoustical_oceanographyhttp://en.wikipedia.org/wiki/Ocean_currenthttp://en.wikipedia.org/wiki/Tidehttp://en.wikipedia.org/wiki/Ocean_surface_wave


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Major Oceans

The three major oceans are :1._______-largest, deepest, coldest, least salty.2.__________- second largest, shallow, warm,

salty.3. _________- intermediate in depth,temperature, and salinity.

The _______Ocean near the north pole, and the____________ Ocean near the south polecontain vast expanses of sea ice.

Pacific

Atlantic

Indian

ArcticAntarctic



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Methods of Studying the Ocean

The Topex/Poseidon_____________ orbits 1331km above the Earth, gathering information aboutthe oceans.

_____________ maps ocean floor topographyby timing how long it takes sound waves tobounce off the ocean floor.

Underwater vessels called _________________investigate the deepest ocean trenches.

satellite

Sonar

submersibles



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Sonar (also called echo-sounding)

Sound waves travelhow fast in seawater?

How deep is thewater if it takes tenseconds for the sound

wave to go from shipto ocean floor andback to ship?

1,454 m/s

7,270 m

Calculation: (10 s times 1,454 m/s divided by 2 ) 6

Diploma in Idustrial LaboratoryTechnology Yr 2,2009


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The picture below is of a _____________.submersible



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Salinity

The amount of salt per unit water is known as salinity.

The average salinity of seawater is _____ ppt. Therefore, forevery 1,000 ml water, there are ___ grams of dissolved salts.

The most abundant salt in seawater is ________, butthere are many other salts present in the form of ions.

Near the equator salinity is __________ than average due to___________________.

Near the poles salinity is __________ than average due to_______________.

In the Mediterranean the salinity is __________thanaverage due to __________.

NaCl

35

35

lowergreater precipitation

lower

melting sea ice

higher

evaporation8Diploma in Idustrial LaboratoryTechnology Yr 2,2009


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The salinityhere would

likely be:

A. 35 ppt

B. 34 ppt

C. 36 ppt



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Colorful Seawater

What makes the oceanwater in the picture tothe left different colors?

Why would a shrimp thatappears bright red at thesurface appear black at

greater depths, and whymight this be beneficial?

differences in depth

Longer (red) wavelengths areabsorbed before reachingdeep water. Shrimp can hide

and not become a meal. 10Diploma in Idustrial LaboratoryTechnology Yr 2,2009


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Label the three ocean layers in the diagram below.

Surface layer

Thermocline

Bottom layer



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Label the wave diagram below with the followingterms: wavelength, waveheight, trough, crest

Ocean Movements

trough

crest

wavelength

waveheight



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0

5

10

15

20

25

30

0 4 8 12 16 20 24

Semidiurnal

Mixed

Diurnal

Tides

Label the keywith thecorrect tide

cycle names:

semidiurnal

mixed

diurnal



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Match the following terms totheir correct letter in the

diagram:

A

B

C

D

E

D

F

G

H

Island

Continental shelf

Continental slope

Abyssal plain

Seamount

Continental rise

Trench

Guyot

Seafloor Topography

A.

B.

C.

D.

E.

F.

G.

H.



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Listed below are some of the major surface currents. The forcewhich generates these currents is ____________.wind



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Review Questions1. What is the average salinity of seawater?

2. What is the deepest area of the seafloor?3. What is the largest ocean?

4. Why is the ocean blue?

5. What is the force responsible for surface currents?

6. What causes density currents?

7. What causes tides?

8. List the 3 tidal patterns.

9. What is the highest part of a wave called?

10.Name the ocean that borders Virginia.

35 ppt

trench

Pacific

shorter wavelengths not absorbed

wind

differences in temperature andsalinity

gravity of the sun and moon

diurnal, semidiurnal, mixed

crest

Atlantic



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2. Chemical oceanography,

or marine chemistry, is the study of thechemistry of the ocean and its chemicalinteraction with the atmosphere

http://en.wikipedia.org/wiki/Chemical_oceanographyhttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Chemical_oceanography


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3.Biological oceanography:

or marine biology, is the study of the

plants, animals and microbes (biota) ofthe oceans and their ecological interaction

http://en.wikipedia.org/wiki/Marine_biologyhttp://en.wikipedia.org/wiki/Biota_(ecology)http://en.wikipedia.org/wiki/Ecologyhttp://en.wikipedia.org/wiki/Ecologyhttp://en.wikipedia.org/wiki/Biota_(ecology)http://en.wikipedia.org/wiki/Marine_biologyhttp://en.wikipedia.org/wiki/Marine_biology


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Ocean Water and

Ocean Life



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Composition of seawater

Seawater consists of about 3.5% (byweight) dissolved minerals

Salinity Total amount of solid material dissolved in

water

Typically expressed in parts-per-thousand()

Average salinity is 35

Major constituent is sodium chloride 20Diploma in Idustrial LaboratoryTechnology Yr 2,2009

f


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Relative proportions of waterand dissolved components in

seawater



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Sources of sea salts

Chemical weathering of rocks

Outgassing gases from volcanic eruptions

Processes affecting seawater salinity

Variations in salinity are a consequence of

changes in the water content of thesolution

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Processes that decrease salinity (add

water) Precipitation Runoff from land Icebergs melting Sea ice melting

Processes that increase salinity (removewater)

Evaporation 23Diploma in Idustrial Laboratory



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Surface salinity in the open ocean ranges

from 33 to 38

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Ocean temperature

Surface water temperature varies withthe amount of solar radiation received

Lower surface temperatures are found inhigh-latitude regions

Higher temperatures found in low-latitude

regions

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Ocean temperature

Temperature variation with depth

Low-latitudes

High temperature at the surface Rapid decrease in temperature with depth

(thermocline)

High-latitudes

Cooler surface temperatures No rapid change in temperature with depth

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Variations in ocean watertemperature with depth

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Ocean temperature

Ocean temperature over time

The unique thermal properties of seawater

make it resistant to temperature changes Global warming could eventually influence

ocean temperatures

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Variations in the oceans

surface tem-perature and

salinity with latitude

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Ocean density

Density is mass per unit volume - howheavy something is for its size

Determines the waters vertical positionin the ocean

Factors affecting seawater density

Salinity

Temperature - the greatest influence

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Ocean density

Variations with depth

Low-latitudes

Low density at the surface Density increases rapidly with depth

(pycnocline) because of colder water

High-latitudes

High-density (cold) water at the surface Little change in density with depth

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Variations in ocean waterdensity with depth

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Ocean density

Ocean layering

Layered according to density

Three-layered structure Surface mixed zone

Sun-warmed zone

Zone of mixing

Shallow (300 meters)

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Ocean density

Ocean layering

Three-layered structure

Transition zone Between surface layer and deep zone Thermocline and pycnocline

Deep zone

Sunlight never reaches this zone Temperatures are just a few degrees above

freezing

Constant high-density water

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Layering in the ocean

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Ocean life

Marine environment is inhabited by awide variety of organisms

Most organisms live within the sunlightsurface waters (photosynthesis)

Classification of marine organisms

Plankton FloatersAlgae (phytoplankton)

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Ocean life


Plankton

Animals (zooplankton) Bacteria Most of Earths biomass

Nekton

All animals capable of moving independently ofthe ocean currents

They are unable to move throughout thebreath of the ocean

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Ocean life


Benthos

Bottom dwellersA great number of species exist on the shallow

coastal floor

Most live in perpetual darkness in deep water

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Ocean life

Marine life zones

Several factors are used to divide the

ocean into distinct marine life zonesAvailability of light

Photic (light) zone

Upper part of ocean

Sunlit

Euphotic zone is near the surface wherethe light is strong

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Ocean life

Marine life zones


ocean into distinct marine life zonesAvailability of light

Aphotic (without light) zone

Deep ocean

No sunlight

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Ocean life

Marine life zones


ocean into distinct marine life zones Distance from shore

Intertidal zone area where land and oceanmeet and overlap

Neritic zone seaward from the low tideline, the continental shelf out to the shelfbreak

Oceanic zone beyond the continental shelf

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Ocean life

Marine life zones Several factors are used to divide the

ocean into distinct marine life zones Water depth Pelagic zone open ocean of any depth

Benthic zone includes any sea-bottomsurface

Abyssal zone a subdivision of the benthiczone

Deep

Extremely high water pressure

Low temperatures 42Diploma in Idustrial Laboratory



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Ocean life

Marine life zones


ocean into distinct marine life zones Water depth

Abyssal zone a subdivision of the benthiczone

No sunlight

Sparse life

Food sources include decaying particlesfrom above, large fragments falling, and

hydrothermal vents 43Diploma in Idustrial Laboratory



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Marine life zones

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Oceanic Productivity

Related to primary productivity

The amount of carbon fixed by organisms

through the synthesis of organic matter Sources of energy

Photosynthesis (solar radiation) Chemosynthesis (chemical reactions)

Influenced by

Availability of nutrientsAmount of solar radiation

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Related to primary productivity

Most abundant marine life exists where

there is ample Nutrients Good sunlight

Productivity in polar oceans Because of nutrients rising from deeper

water, high-latitude surface waters havehigh nutrient concentrations

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Productivity in polar oceans

Low solar energy limits photosynthetic

productivityProductivity in tropical oceans

Low in the open ocean

Thermocline eliminates the supply ofnutrients from deeper waters below

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An example of productivity inpolar oceans (Barents Sea)

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Productivity in tropical


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Productivity in tropicaloceans

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Productivity in temperate oceans

Winter

Low productivity Days are short and sun angle is low

Spring

Spring bloom of phytoplankton is quicklydepleted

Productivity is limited

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Productivity in temperate oceans Summer

Strong thermocline develops so surface

nutrients are not replaced from below Phytoplankton population remains relatively low

Fall Thermocline breaks down and nutrients return

to the surface Short-lived fall bloom of phytoplankton

Highest overall productivity occurs intemperate regions

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Productivity in temperate

oceans(Northern Hemisphere)

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Oceanic feedingrelationships

Main oceanic producers

Marine algae

Plants Bacteria

Bacteria-like archaea

Only a small percentage of the energytaken in at any level is passed on to thenext

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Trophic levels

Chemical energy stored in the mass of the

oceans algae is transferred to the animalcommunity mostly through feeding

Each feeding stage is called a trophic level

Transfer of energy between trophiclevels is very inefficient (about 2%)

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Ecosystem energy flowand efficiency

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Food chains and food webs

Food chain - a sequence of organisms

through which energy is transferred Food web

Involves feeding on a number of differentanimals

Animals that feed through a food web ratherthan a food chain are more likely to survive

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Comparison between a foodchain and a food web

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4.Marine Geology:The Ocean Floor

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Geography of oceans

Marine Geology

The sea floor

Continental margins

Ocean basin floor

Ocean ridges

Seafloor sediments

Resources

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The vast world ocean

Earth is often referred to as the blueplanet

Seventy-one percent of Earths surface isrepresented by oceans and marginal seas

Continents and islands comprise theremaining 29

Northern Hemisphere is called the landhemisphere, and the SouthernHemisphere the water hemisphere

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Views of the

Northern andSouthernhemispheres

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The vast world ocean

Four main ocean basins

Pacific Ocean - the largest and has the

greatest depthAtlantic Ocean about half the size of the

Pacific and not quite as deep

Indian Ocean slightly smaller than theAtlantic, largely a southern Hemispherebody

Arctic Ocean about 7 percent the size of

the Pacific 62Diploma in Idustrial Laboratory


Th f E th


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The oceans of Earth

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Mapping the ocean floor

Bathymetry measurement of oceandepths and the charting of the shape or

topography of the ocean floorEcho sounder (also referred to as

sonar)

Invented in the 1920s Primary instrument for measuring depth

Reflects sound from ocean floor

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Echo sounder andmultibeam sonar

Figure 13.4 A 65Diploma in Idustrial Laboratory



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Multibeam sonar

Employs and array of sound sources and

listening devices Obtains a profile of a narrow strip of

seafloor

Measuring the shape of the oceansurface from space

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Three major topographic units of theocean floor

Continental margins Ocean basin floor

Mid-ocean ridge

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Major topographic divisionsof the North Atlantic Ocean

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Continental margins

Passive continental margins

Found along most coastal areas that

surround the Atlantic Ocean Not associated with plate boundaries

Experience little volcanism and Few earthquakes

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Continental margins


Features comprising a passive continental

margin Continental shelf

Flooded extension of the continent

Varies greatly in width

Gently sloping

Contains oil and important mineral deposits

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Continental margins



margin Continental shelf

Some areas are mantled by extensive glacialdeposits

Most consist of thick accumulations ofshallow-water sediments

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Continental margins



margin Continental slope

Marks the seaward edge of the continentalshelf

Relatively steep structure Boundary between continental crust and

oceanic crust

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Continental margins



margin Submarine canyons and turbidity currents

Submarine canyons

Deep, steep-sided valleys cut into the

continental slope Some are seaward extensions of river

valleys

Most appear to have been eroded by

turbidity currents 73Diploma in Idustrial Laboratory



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Continental margins



margin Submarine canyons and turbidity currents

Turbidity currents

Downslope movements of dense,

sediment-laden water Deposits are called turbidites

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Turbidity currents


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Turbidity currents

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Continental margins

Passive continental margins Features comprising a passive continental

margin Continental rise

Found in regions where trenches are absent

Continental slope merges into a moregradual incline the continental rise

Thick accumulation of sediment

At the base of the continental slopeturbidity currents that follow submarinecanyons deposit sediment that forms deep-

sea fans 76Diploma in Idustrial Laboratory


Features of a passive


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Features of a passivecontinental margin

Figure 13.9 77Diploma in Idustrial Laboratory



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Continental margins

Active continental margins

Continental slope descends abruptly into a

deep-ocean trench Located primarily around the Pacific Ocean

Accumulations of deformed sediment andscraps of ocean crust form accretionarywedges

Some subduction zones have little or noaccumulation of sediments

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Ocean basin floor

Deep-ocean trenches

Long, relatively narrow features

Deepest parts of ocean Most are located in the Pacific Ocean

Sites where moving lithospheric plates

plunge into the mantleAssociated with volcanic activity

Volcanic islands arcs Continental volcanic arcs

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An active continental


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margin

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Ocean basin floor

Abyssal plains

Likely the most level places on Earth

Sites of thick accumulations of sediment Found in all oceans

Seamounts and guyots

Isolated volcanic peaks Many form near oceanic ridges

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Ocean basin floor

Seamounts and guyots May emerge as an island

May sink and form flat-topped seamountscalled guyots or tablemounts

Mid-ocean ridge Characterized by

An elevated position Extensive faulting Numerous volcanic structures that have

developed on newly formed crust

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Ocean basin floor

Mid-ocean ridge

Interconnected ridge system is the longest

topographic feature on Earths surface Over 70,000 kilometers (43,000 miles) in

length

Twenty-three percent of Earths surface

Winds through all major oceansAlong the axis of some segments are deep

downfaulted structures called rift valleys

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Ocean basin floor

Mid-ocean ridge

Consist of layer upon layer of basaltic rocks

that have been faulted and uplifted Mid-Atlantic Ridge has been studied more

thoroughly than any other ridge system

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Seafloor sediments

Ocean floor is mantled with sediment

Sources

Turbidity currents Sediment that slowly settles to the bottom

from above

Thickness varies Thickest in trenches accumulations may

approach 10 kilometers

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Seafloor sediments

Thickness varies

Pacific Ocean about 600 meters or less

Atlantic Ocean from 500 to 1000 metersthick

Mud is the most common sediment on

the deep-ocean floor

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Seafloor sediments

Types of seafloor sediments

Terrigenous sediment

Material weathered from continental rocksVirtually every part of the ocean receives some Fine particles remain suspended for a long time Oxidation often produces red and brown

colored sediments

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Seafloor sediments


Biogenous sediment

Shells and skeletons of marine animals andplants Most common are calcareous oozes produced

from microscopic organisms that inhabit warm

surface waters Siliceous oozes composed of skeletons ofdiatoms and radiolarians

Phosphate rich materials derived from the

bones, teeth, and scales of fish and other 88Diploma in Idustrial Laboratory



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Seafloor sediments


Hydrogenous sediment

Minerals that crystallize directly from seawater Most common types include Manganese nodules

Calcium carbonates

Metal sulfides

Evaporites

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Distribution of marine


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Distribution of marinesediments

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Seafloor sediments

Distribution

Coarse terrigenous deposits dominate

continental margin areas Fine-grained terrigenous material is

common in deeper areas of the oceanbasin

Hydrogenous sediment comprises only asmall portion of deposits in the ocean

There are a few places where very little

sediment accumulates (Mid-ocean ridges) 91Diploma in Idustrial Laboratory



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Resources from the seafloor

Energy resources

Oil and gas

Gas hydratesOther resources

Sand and gravel

Evaporative salts Manganese nodules

Documents

Introduction to Marine Science (G5405)