Oceanography Exam 1 Study Guide

Front 1

What are the differences between hydrosphere, cryosphere atmosphere, geosphere, lithosphere and biosphere?

Back 1

Hydrosphere: includes water in solid liquid, and gas forms
Cryosphere: the frozen part of the hydrosphere
Atmosphere: gasses and suspended particles surrounding the planet
Geosphere: Solid - rocks, minerals and sediments
Lithosphere: composed of uppermost mantle and crust divided into riged plates that move and interact
Biosphere: all living organisms

Front 2

What % of the earths surface is covered by oceans?

Back 2

71%

Front 3

What are the two most abundant gasses in the atmosphere and the percentage by each volume?

Back 3

Nitrogen at 78%
oxygen at 21%

Front 4

The interior of the earths four layers are

Back 4

Inner Core - solid
Outer core - liquid
Mantle - solid
Crust - solid

Front 5

How do we know about the four layers of the earth surface?

Back 5

from seismic waves (earthquakes)

Front 6

What is the lithosphere and which part of the earths four layers compose the lithosphere?

Back 6

•
• uppermost mantle and crust

Front 7

The difference between inner core and outer core?

Back 7

• inner core is solid
• outer core is liquid

Front 8

What is the difference between weathering and erosion

Back 8

• weathering: physical or chemical breakdown of rocks
• erosion is: removal and transportation of rock fragments by running water, ice, or landslides

Front 9

Describe global water cycle in terms of evaporation, transpiration, sublimination, condensation, precipitation, deposition, run-off, and infiltration

Back 9

• evaporation: water - liquid to gas
• transpiration: water - vapor released by plants into atmosphere
• sublimination: water - solid to gas
• condensation: water - gas to liquid
• precipitation: water - rain or snow
• deposition: water gas to solid
• run-off: water - flowing on surface of earth
• infiltration: surface of earth into the ground

Front 10

In which of Earth’s 4 spheres (Earth System) do the parts of the Global Water Cycle take place?

Back 10

• Evaporation - hydrosphere to atmosphere
• Sublimation - hydrosphere to atmosphere
• transpiration - biosphere to atmosphere
• condensation - atmosphere to hydrosphere
• precipitation - atmosphere to hydrosphere
• Infiltration - hydrosphere to geosphere
• runoff - hydrosphere

Front 11

In which of Earth’s 4 spheres does evaporation take place?

Back 11

hydrosphere to atmosphere

Front 12

In which of Earth’s 4 spheres does sublimation take place?

Back 12

hydrosphere to atmosphere

Front 13

In which of Earth’s 4 spheres does condensation take place?

Back 13

hydrosphere and atmosphere

Front 14

In which of Earth’s 4 spheres does deposition take place?

Back 14

atmosphere and hydrosphere

Front 15

Which spheres are involved in infiltration?

Back 15

hydrosphere and geosphere - because it goes into the ground

Front 16

Which is older, continental or oceanic crust?

Back 16

Continental Crust

Front 17

Which is denser- continental or oceanic crust?

Back 17

Oceanic crust - tt will always move under the continental crust

Front 18

How does is the continental shelf, slope, and rise differ between tectonically active and tectonically passive continental margins?

Back 18

• Active - narrow continental shelf, steep continental slope, trench instead of continental rise
• Passive - wide, flat continental shelf, gentle continental slope, continental rise

Front 19

In which ocean (Atlantic or Pacific) are there more Abyssal Plains? In which ocean are there more trenches? Why?

Back 19

There are more abyssal plains in the Atlantic because in the Pacific the trenches trap the sediment as it comes off shore. The sediment gets stuck in the trenches and does not reach the open ocean basin floor and thus does not have the opportunity to create abyssal plains.

Front 20

How does an atoll form?

Back 20

• Step 1: Volcano forms. Reef begins to grow in shallow water on flanks of volcano.
• Step 2: Volcano is extinct and begins to erode. A shallow lagoon separates the volcano from the reef.
• Step 3: Volcano erodes below sea level. The reef may grow until it eventually breaks above the surface.

Front 21

What happens to age of the ocean floor as you move away from the axis of a ridge?

Back 21

Age of the floor increases

Front 22

What happens to water depth?

Back 22

Depth increases

Front 23

What happens to heat flow from the mantle?

Back 23

Heat flow increases

Front 24

What would happen to the circumference of the Earth if there was subduction, but not sea-floor spreading?

Back 24

If there was subduction, but not sea-floor spreading, the Earth would get smaller.

Front 25

What would happen if there was sea-floor spreading but not subduction?

Back 25

the Earth would get larger

Front 26

Which part of the seafloor is older, the middle or the near the coast?

Back 26

The oldest seafloor is near the coast.

Front 27

How do magnetic anomalies support plate tectonics and seafloor spreading?

Back 27

Magnetic anomalies record the movement of the plates, the age of the rocks, and the magnetic reversals. They can be used to track the movement
of the plates over the past.

Front 28

What are the plates made of?

Back 28

Lithosphere

Front 29

What is the driving force of movement?

Back 29

Convection

Front 30

Are there earthquakes at divergent plate boundaries? Is there volcanic activity?

Back 30

• Yes
• Yes

Front 31

Are there earthquakes and volcanoes at oceanic-oceanic convergent plate boundaries?

Back 31

• Yes
• Yes

Front 32

In an Oceanic-Continental Convergent plate boundary, which plate is denser? Why is it denser?

Back 32

Oceanic is denser because of the amount of iron and magnesium

Front 33

Are there volcanoes and earthquakes at oceanic-continental convergent plate boundaries?

Back 33

• Yes
• Yes

Front 34

Are there earthquakes at continental-continental convergent plate boundaries?

Back 34

Yes

Front 35

Are there earthquakes at Transform Plate Boundaries?

Back 35

Yes

Front 36

Which Plate Boundaries have earthquakes??

Back 36

All of Them

Front 37

Which Plate Boundaries have volcanic activity?

Back 37

Divergent, Oceanic-Oceanic convergent, Oceanic-Continental convergent

Front 38

Which direction is the Pacific Plate moving?

Back 38

The Pacific Plate is moving towards the North-west.

Front 39

Which of the Hawaiian Islands is the oldest?

Back 39

Kauai

Front 40

Which is the Youngest?

Back 40

The big island of “Hawaii” is the youngest.

Front 41

Which is closest to the hot spot?

Back 41

The big island of “Hawaii” is closest to the Hot Spot

Front 42

Which plate boundary is closest to Utah going East?

Back 42

Mid-Atlantic Ridge

Front 43

Which plate boundary is closest to Utah going West?

Back 43

The San Andreas Fault

Front 44

Why is the polarity of water important?

Back 44

Because water is polar, it has a net positive charge on one side and a net negative charge on the other side. This allows water molecules to bond via hydrogen bonding to other water molecules. It also allows other substances like sodium to dissolve easily in water.

Front 45

Compare the temperature range between the two cities. Why is the range so much greater inland that it is near the coast? What can you say about the temperature range of city on the coast versus a city inland?

Back 45

• Because water absorbs heat without changing temperature, the city on the coast does not get as hot in the summer. In the winter, the city near the coast uses the heat absorbed by the water in the summer to keep warm, thus it does not get as cold.
• The city inland is much hotter in the summer and much colder in the winter.

Front 46

Why is Edmonton colder in the winter and warmer in the summer?

Back 46

Edmonton is inland. It does not have the ocean to keep it warm in the winter and cool in the summer. Juneau is on the coast. The ocean absorbs a lot of energy during the summer, then releases that energy in the winter, keeping Juneau warm. It absorbs all the energy in the summer, which keeps Juneau cool.

Front 47

Why is most of the ocean light blue (no difference between the temperature during the day and the temperature at night)?

Back 47

• There is no difference between the day and night temperature of the ocean because during the day, the ocean absorbs energy from the
sun, keeping the day cooler.
• During the night, the ocean releases the energy it absorbed during the day, keeping the night warmer.

Front 48

To increase salinity, would you melt or form sea ice?

Back 48

Form sea ice

Front 49

What about decreasing salinity?

Back 49

melt sea ice

Front 50

Would precipitation over the oceans increase or decrease salinity?

Back 50

Precipitation decreases salinity

Front 51

Does evaporation increase or decrease salinity?

Back 51

Evaporation increases salinity

Front 52

What is the pressure if the depth is equal to 3500 m?

Back 52

350 kg/cm2

Front 53

What is the depth if the pressure is equal to 24.5 kg/cm3?

Back 53

245 m

Front 54

Where will there be the greatest accumulation of lithogeneous sediments?

Back 54

Closest to the continents

Front 55

Clay sized sediment from the Sahara Desert has been found in the Caribbean. How did it get there?

Back 55

May have been transported by wind or ocean currents.

Front 56

What is methane hydrate?

Back 56

A solid form of methane bonded with water

Front 57

Where are methane hydrate deposits located?

Back 57

Continental shelf and slope deposits

Front 58

Why is methane hydrate important?

Back 58

It can be used as an energy source for the future

Front 59

How can calcareous oozes be found at depths greater than 4500 m?

Back 59

Calcareous oozes can be found at depths greater than 4500 m if they are buried by another type of sediment before being moved (via plate tectonics) to deeper water.

Front 60

Continental Crust

Back 60

• Type of crust that is thick
• Composed mostly of granite, rich in silicon and aluminum,
• Has a low density but is thicker

Front 61

Specific Heat

Back 61

The amount of heat that will raise a gram of saple of a substance by 1 degree C

Front 62

Hot Spot

Back 62

Forms when a plate moves over a mantle plume (NOT a plate boundary)

Front 63

Geostationary

Back 63

A type of satellite that remains over a fixed point of the Earth.

Front 64

Neriic Deposits

Back 64

Near Shore Lithogeneous deposits

Front 65

Hydrogeneous sediment

Back 65

Sediment that is precipitated from water

Front 66

Lithogeneous sediment

Back 66

Sediment from weather and erosion of continents

Front 67

Coral Atoll (in French Polynesia)

Back 67

Rin shaped island surrounding a lagoon, formed on eroding volcano

Front 68

Pangaea

Back 68

Name of the super Continent proposed by Alfred Wegener

Front 69

Foraminifera and Cocolithophre

Back 69

Are both organisms that make up calcareous ooze

Front 70

Polar orbiting satellite

Back 70

Satellite that orbits the outer poles

Front 71

Biogeneous sediment

Back 71

Sediment that has its source from life, once dead organisms, bones, etc

Front 72

Oceanic Crust

Back 72

Part of the earth that is solid, and very dense

Front 73

Transform Plate Boundary

Back 73

The type of boundary hwere two plates slide past eachother

Front 74

Calcereous Oozes

Back 74

• Water shallower than 4500 m
• Make shells out of CaCO3 (calcium carbonate)
• Foraminifera - single cells
• Cocolithopher - single celled algae, photosynthetic

Front 75

Convection

Back 75

mechanism for plate movement

Front 76

Evaporation

Back 76

• Liquid water that changes into water vapor without boiling

Front 77

Divergent Plate Boundary

Back 77

Type of plate boundary where plates move away from each other

Front 78

Biosphere

Back 78

Part of Earth that is made up of living organisms

Front 79

Cosmogeneous sediment

Back 79

Marine sediment from space

Front 80

Convergent plate Boundary

Back 80

The type of plate boundary where plates collide

Front 81

Covalent Bond

Back 81

Type of bond holding one water molecule to another water molecule

Front 82

Cryosphere

Back 82

Frozen part of the hydrosphere

Front 83

Two examples of a continental-continental convergent plate boundary

Back 83

• Himalayas
• St. Andreas Fault

Front 84

Cosmogeneous sediment

Back 84

• Comes from space
• Meteorites: small % of seafloor sediments, infrequent burns up in atmosphere
• Space dust: micro-filaments that fall through atmosphere
• Tektites a form of rock that is melted or has melted when hit by a meteorite

Front 85

Tektites are

Back 85

• A form of rock that is melted or has melted when hit by a meteorite.
• A form of Cosmogeneous sediment

Front 86

Submarine Canyons

Back 86

These are cared into continental slope by turbidity currents

Front 87

Type of crust that is thin, composed of basalt, rich in iron and magnesium and is very dense

Back 87

Oceanic Crust

Front 88

Hydrosphere

Back 88

Part of the earth that includes water as a solid, liquid, and gaseous forms

Front 89

Atmosphere

Back 89

Gases and suspended particles surrounding the planet

Front 90

Flat, very flat areas of the seafloor

Back 90

Abyssal Plains

Front 91

Divergent

Back 91

Plates move away from eachother

Front 92

Hydrothermal Vents

Back 92

underwater hot springs

Front 93

Pillow Basalts

Back 93

pillow shaped rocks, formed from lava flow under the water

Front 94

Taypes of Water Changes

Back 94

Evaporation -
Sublimation
Transpiration
Deposition
Infiltration
Condesnsation
Preicpitation
Run0ff

Front 95

Marine Sediment Deposits

Back 95

• Neritic Deposits - Delta and lithogeneous, larger grain size - Near the shore
• Palegic Deposits - Deep ocean basins. Calcareous Oozes - Siliceous oozes
• Source for most is in erosion from the continents
• Also can be can be considered tectonically passive

Front 96

Neritic Deposits

Back 96

• Delta and Lithogeneous
• Larger grain size
• Near the shore

Front 97

Palegic Deposits

Back 97

• Deep ocean basins
• Calcareous Oozes
• Siliceous oozes

Front 98

Sediment Deposit (n mid--ocean locations)

Back 98

Sediment thickness
• 5c per 1000 years
• .005 er 1,000 years

Front 99

Ice-Rafted Glacial Sediments

Back 99

Occures mostly on the floor of a polar ocean

Front 100

Deep Sea Muds (Clays)

Back 100

Found primarily in the mid-ocean basins

Front 101

Submerged River/Valley Submarine Canyons

Back 101

Acts as a conduit to move sediments from the continental shelf to the base of the continental slope

Front 102

Types of sediment flow/transport

Back 102

Rivers: in tropics great than in higher altitudes, greater sediment input in summer
Streams: sediments are near rivers on earth
Basins: Extensive vegetation cover makers sediment flow/transportation

Front 103

Annual Sediment Transport

Back 103

• Greatest average is the Houng Ho River
• All factors equal
a. greater sediment input into ocean by rivers is in summers
b. tropics transport greater sediment load than a river located at high altitudes

Front 104

Limestone

Back 104

• is resulted from the li of calcareous oozes that was transported from a location closer to the Mid-Atlantic ridge

Front 105

Calcareous Oooze

Back 105

• 30% calcareous organisms
• found in depths less than 4500 miles
• can be found below depth of 4500 miles if they are burried y another type of sediment before being moved
• Mid-Atlantic ridge can be found limited as limestone Organisms:
- - Foraminifera - single cells
- - Cocolithophore - single celled algae, photosynthetic
• Dissolves n deep water

Front 106

Lithogeneous Sediment

Back 106

• in continental margins, in principle source is the river discharge and erosion of offshore materials
• are Neritic Deposits
• Thickest sediments

Front 107

Carbonate Composition Depth (CCD)

Back 107

The depth of the ocean below which calcium carbonate dissolves and does not accumulate on the ocean floor.

Front 108

Biogeneous sediments

Back 108

• From living organisms or their remas
- - includes shells bones, coral, skeletal parts
- - includes excretions and secretions

Front 109

Siliceous Ooze

Back 109

30% siliceous organisms (distances/radiolarians)
• Can be found at any depth

Front 110

Diatoms

Back 110

Dominant high latitudes ocean locations - single celled algae and photosynthetic

Front 111

Radiolarians

Back 111

Are in upwelling zones - single celled

Front 112

Red Clay

Back 112

• Origin of red clay is land
• Dominant in ocean water deeper than 4500 miles.

Front 113

Neritic Deposits

Back 113

• Larger gain size
• near shore - continental margins
• Lithogeneous
• In Delta and Wetlands

Front 114

Delta

Back 114

• Fan shaped deposit formed when a stream enters the ocean and drops all of its sediment

Front 115

Wetlands

Back 115

Low lying flat areas. Covered as water at least part of the year.

Front 116

Calving

Back 116

When a piece of glacier breaks off, forms icebergs

Front 117

Delta

Back 117

Fan shaped deposit continental rise at the base of the submarine canyon.

Front 118

Pelagic Deposits

Back 118

• Deep ocean basins
• Calcareous Oozes
• Siliceous Oozes

Front 119

Hydrogeneous Sediments

Back 119

Precipitated from seawater
• Ooliths - tiny sphere of calcite
• Manganize nodules

Front 120

Manganese Nodules

Back 120

• Black Nodules
• Manganese, iron, copper cobalt, and nickel
• Form as coatings

Front 121

Distribution of Biogeneous and Lithogenous Sediments on the seafloor

Back 121

BIOGENEOUS SEDIMENT
• Calcareous
• Radiolarians
• Diatoms
LITHOGENEOUS SEDIMENT
• Deep-Sea Muds
Terrigeous
• Glacial-marine

Front 122

Neritic Deposits

Back 122

• Larger grain size
• Near Shore - contnental margins
• Lithogeneous

•Delta (where a river enters the ocean)
• Wetlands

Front 123

Part of Earth that includes water in solid, liquid, and gaseous forms

Back 123

Hydrosphere

Front 124

An example of continental-continental convergent plate boundary

Back 124

Himalayas
St Andreas Fault

Front 125

Sediment coming from weather and erosion from the continents

Back 125

Lithogenous Sediment

Front 126

Sediment precipitated from seawater

Back 126

Hydrogeneous

Front 127

Example of a hot spot

Back 127

French Pyrenees

Front 128

Flat, very flat areas of sea floor

Back 128

Abyssal Plane

Front 129

These organisms make up a Siliceous Ooze

Back 129

• Diatoms
• Radiolarians

Front 130

Exclusive Economic Zones (EEZ)

Back 130

• Extends 200 nautical miles offshore of country
• Or to edge of continental shelf (if further than 200 nautical miles offshore)

Front 131

Oil and Natural Gas

Back 131

• Organicmatter (biogeneous sediments) accumulate in shallow sea

Front 132

Gas Hydrates

Back 132

• Read 256-258
• Solidformofmethane
• Found in sediment on continental shelf and slope

Front 133

How does the atmosphere affect the oceans?

Back 133

The atmosphere and oceans are constantly exchanging H2O through evaporation and precipitation.

Front 134

How do the oceans affect the atmosphere?

Back 134

The temperature of one
affects the temperature of the other. Wind in the atmosphere affects ocean waves and currents.

Front 135

How does the continental shelf, slope, and rise differ between tectonically active and tectonically passivly continental margins?

Back 135

• Active - Narrow continental shelpf, steep continental slope, trench instead of continental rise.
• Passive - wide, flat continental shelf, gentle continental slope, continental rise

Front 136

Tectonically Active continental margins

Back 136

Active - Narrow continental shelpf, steep continental slope, trench instead of continental rise

Front 137

Tectonically Passive continental margins

Back 137

Passive - wide, flat continental shelf, gentle continental slope, continental rise

Front 138

How do we know what the interior of the earth is like?

Back 138

We know about the Earth’s interior structure from seismic waves (earthquakes).

Front 139

Which U.S. coastline is tectonically active? Tectonically passive?

Back 139

Active - U.S. West coast, Passive - Gulf and East coast

Front 140

What happens to water depth moving from the continental shelf to the continental rise?

Back 140

Water depth increases rapidly over the continental slope and continental rise

Front 141

Looking at Fig 2.5 of page 39 , which (r/l) is tectonically active? Tectonically passive? Which one (active or passive) lacks a continental rise?

Back 141

Active - left side - lacks a continetnal rise. Passive - right side

Front 142

In which oean (Atlantic or Pacific) are there more Abyssal Planes?

Back 142

There are more abyssal plains in the Atlantic because in the Pacfic the trenches traps the sediment as it comes off the shore.

Front 143

In which ocean are there more trenches? Why

Back 143

The sediment gets stuck in
the trenches and does not reach the open ocean basin floor and thus does not have the opportunity to create abyssal plains.

Front 144

Which spheres are involved in infiltration

Back 144

•Biosphere
• Hydropshere

Front 145

Part of Earth made up of living organisms

Back 145

Biosphere

Front 146

Abbreviation for the depth at which calcium caronate dissolves

Back 146

CCD

Front 147

The Aleutian islands are this type of convergent plate boundary

Back 147

Ocean-Continent Convergent Boundary

Front 148

Features of the Ocean Floor: Abyssal Plains

Back 148

• Flat, Very Flat areas of sea floor
• Form seaward of continental rise
• Result of Sediment settling out of water and burying any or all topography
• Deep

Front 149

Evidence for Continental Drift

Back 149

1. ContinentalFit
2. Fossils
3. LinearMountainRanges

Front 150

Sea-Floor Spreading

Back 150

• Plates in the middle of the ocean move away from each other
• ProposedbyHarry Hess

Front 151

Mid Ocean Ridges

Back 151

• Seafloor spreading occurs at mid ocean ridges.

Front 152

Subduction

Back 152

• LithosphericPlates descend into mantle
• Destroysoceanic crust

Front 153

Magnetic Anomalies

Back 153

• Iron in rocks aligns with magnetic field of Earth
• The Earth’s magnetic field reverses polarity
• Reversals are recorded on seafloor
• The pattern on one side of an ocean is a mirror image of the pattern on other side

Front 154

What causes the plates to move?

Back 154

Convection

Front 155

Convection

Back 155

• Convection is the mechanism for plate movement.
– Heat rises (seafloor spreading) – Cold sinks (subduction)

Front 156

Plate Boundary Movement

Back 156

• Plate boundaries can be classified as 3 different types depending on the dominant direction of movement.
– Plates can move away from each other ← → – Plates can crash into each other → ← – Plates can slide past each other

Front 157

Divergent Plate Boundaries

Back 157

• Platesmoveaway from each other (seafloor spreading occurs here)
• Forms mid-ocean ridges

Front 158

Divergent Plate Boundary

Back 158

• NewOceancrustis formed

Front 159

Features of Divergent Boundaries: Pillow Basalts

Back 159

• Pillowshapedrocks formed from lava flows under water

Front 160

Features of Divergent Boundaries: Hydrothermal Vents

Back 160

• Underwater Hot Springs
• Rich in minerals and chemicals,
• Supportlarge communities of organisms by chemosynthesis

Examples
MAR- Mid-Atlantic Ridge EPR- East Pacific Rise RS- Red Sea IR- Indian Rise

Front 161

Convergent Plate Boundaries Subtype A: Oceanic-Oceanic Convergent

Back 161

• Oceaniccrustcollides with oceanic crust
• Oceaniccrustis destroyed
• Thedenserplate subducts

Examples
A- Aleutian Islands J- Japan

Front 162

Oceanic-Oceanic Subduction Zone

Back 162

• Denser plate subducts under less dense plate
• Deep sea trench forms where 2 plates meet
• Subducting plate partially melts- creating a chain of volcanoes parallel to the trench called a volcanic island arc

Front 163

Volcanic Island Arc

Back 163

Aleutian Islands

Front 164

Convergent Plate Boundaries Subtype B: Oceanic-Continental Convergent

Back 164

• OceanicPlatecollides with Continental Plate
• Oceaniccrustis destroyed
• Thedenserplate subducts

Front 165

Oceanic-Continental Convergent

Back 165

Examples
A- Andes Mountans C- Cascades

Front 166

Convergent Plate Boundaries Type 3: Continental-Continental Convergent

Back 166

• Continental plate collides with a continental plate
• No Subduction
• No Volcanoes
• Collidingcrustpushes upward creating mountain ranges

Examples
A- Alps H- Himalayas

Front 167

Continental-Continental Convergent Plate Boundary

Back 167

Himalayas

Front 168

Oceanic-Oceanic

Back 168

– Ocean on both sides- if you are surround by ocean, you must be on an island

Front 169

Oceanic-Continental

Back 169

– Ocean on one side- if you are between the ocean and the continent- you must be at the beach- look for a boundary on a coastline

Front 170

Continental-Continental

Back 170

– In the middle of the continent- no where near the ocean

Front 171

Transform Plate Boundaries

Back 171

• Plateslidepasteach other
• No volcanoes
• Transformboundaries connect other plate boundaries.


• Examples
S- San Andreas Fault

Front 172

Transform Plate Boundaries connect other plate boundaries

Back 172

• The San Andreas Fault (Transform) connects the Juan de Fuca Ridge (Divergent) to the East Pacific Rise (Divergent) in the Gulf of California

Front 173

Hot Spots

Back 173

• NOT A PLATE BOUNDARY!!!
• Mantle plume- stationary column of heat from mantle
• Platemovesovertop of mantle plume
• Spotoncrustover mantle plume is called a “Hot Spot”

Front 174

Pacific Plate

Back 174

The Pacific Plate moves over the mantle plume. Whichever part of the plate is over the mantle plume has active volcanoes. The volcanoes that have moved away from the mantle plume are extinct.

Front 175

Examples of a Hot Spot

Back 175

Examples
H- Hawaii Y- Yellowstone

Front 176

What is this a picture of?

Back 176

Foraminifera

Front 177

What is this a picture of?

Back 177

Diatoms

Front 178

What is this a picture of?

Back 178

Radiolarians

Front 179

What is pictured here?

Back 179

Manganese Nodules

Front 180

What is this a picture of?

Back 180

Ooliths

Front 181

What is this a picture of?

Back 181

Siliceous Sediments

Front 182

What is this an image of?

Back 182

Meteorites

Front 183

What is this a picture of?

Back 183

Space dust

Front 184

What is this a picture of?

Back 184

Tektites

Front 185

What is this a picture of?

Back 185

Wetlands

Front 186

What is this a picture of?

Back 186

Calcareous Ooze

Front 187

What is this diagram showing?

Back 187

Carbonate Compensation Depth (CCD)

Front 188

Back 188

White Cliffs of Dover- formed from rock (rock type is chalk) made of calcareous ooze

Front 189

Back 189

Siliceous Ooze

Front 190

Back 190

Passive Continental Margin- U.S. East Coast

Front 191

Passive Continental Margin

Back 191

• • •
Continental Shelf – Nearly flat
Continental Slope – Anglebetween1°and25°
Continental Rise
– Not as steep as the continental slope
– Marks the boundary between continental and oceanic crust

Front 192

Label the following parts

Back 192

Front 193

Continental Margins- the boundary between oceanic and continental crust

Back 193

2 types:
Figure 2.5, page 39
1. Passive Continental Margins- no plate boundary
2. Active Continental Margins- at/near a plate boundary

Front 194

Continental Crust

Back 194

• Mostlygranite
• Thicker
• Less Dense

Front 195

Continental Rise

Back 195

– Not as steep as the continental slope
– Marks the boundary between continental and oceanic crust

Front 196

Continental Slope

Back 196

Anglebetween1°and25°

Front 197

Continental Shelf

Back 197

Nearly Flat

Front 198

What is this an example of?

Back 198

An active continental margin

Front 199

Simplified Diagram of an Active Continental Margin

Label the following parts: 1. continental shelf 2. continental slope 3. deep sea trench.

Back 199

Label: 1. continental shelf, 2. continental slope, and 3. deep sea trench.

Front 200

Q: Which one (right or left) is tectonically active? Tectonically passive?
Q: Which one (active or passive) lacks a continental rise?

Back 200

• Active- left side- lacks a continental rise
• Passive- right side

Front 201

Lithogeneous Sediment

Back 201

• Sediment from rocks
• Result of weathering and erosion

Front 202

Classification of Lithogeneous Sediment

Back 202

• Based on grain size
– Mud – very small (think of flour or powdered sugar)
– Sand- less than 2 mm in size (think of granulated sugar or a sand box)
– Gravel- anything bigger than 2 mm

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Sorting Lithogeneous Sediment

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• Howmanyofthe grains are the same size.
– Well sorted- all grains same size
– Poorly sorted- grains of all different sizes

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Lithogeneous SedimentComposition

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• Mostlysilicates
• Quartzismost common because it is
– 1. Extremely common – 2. Durable

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Source of Lithogeneous Sediment

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• Streams and run-off from continents
• Wind – Blows dust and clay sized particles to ocean
• Glaciers – Calving- when a piece of the glacier breaks off, forms icebergs
• Landslides

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Biogeneous sediments

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• From living organisms or their remains – Includes shells, bones, coral, skeletal parts – Includes excretions and secretions

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Calcareous Organisms

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• Makeshellsoutof CaCO3 (calcium carbonate)
Examples
• Foraminifera – Single cells
• Coccolithophore – single-celled algae – photosynthetic

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Calcareous Sediments

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• Dissolve in deep water • Found at depths less than ~4500 m

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Siliceous Sediments

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• Makeshellsoutof
SiO2 (silica) Examples
• Diatoms – Single celled algae – Photosynthetic
• Radiolarians – Single celled

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Hydrogeneous Sediments

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Precipitated from seawater

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Manganese Nodules

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• Blacknodules
• Contain Manganese, Iron, copper, cobalt, and nickel
• Formascoatingson other particles

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Ooliths

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• Tinyspheresof calcite
• Precipitateoutof seawater

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Cosmogeneous Sediment

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• Come from space – Meteorites – Space Dust – Tektites

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The type of plate boundary where two plates collide

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Convergent Plate

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The type of bond holding one water molecule to another water molecule

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Hydrogen Bond

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Frozen part of the Hydrosphere

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Cryosphere

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Marine Sediment from space

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Cosmogeneous Sediment

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Part of the earth made up of living organisms

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Biiosphere

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An example of continental-continental convergent plate boundary

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Himalayas

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The type of boundaries where plates move away from each other

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Divergent plate boundaries

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Liquid water changes to water vapor without boiling

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Evaporation

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Abbreviation for the depth at which calcium carbonate dissolves

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CCD

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The mechanism for plate movement

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Convection

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Tye of boundary where two plates slid past each other

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Transform plate boundaries

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Solid form of methane found in sediment on continental shelf and slope

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Methane Hydrate

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Sediment that has its source from life

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Biogeneous Sediment

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One of the organisms that make up Calcareous Ooze

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Foraminifera

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Type of crust that is thin composed of basalt rich in iron and magnesium. and is very dense

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Oceanic Crust

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Name of super-continent proposed by Wegener

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Pangaea

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Ring shaped island surrounding a lagoon, formed on eroding volcano

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Coral Atol

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When pieces of the glacier breaks off, forms icebergs

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Calving

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Breakdown of rock material either physically or chemically

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Weathering

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Flat, very flat areas of sea floor

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Abyssal Planes

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Sediment coming from weather and erosion on the continents

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Lithogeneous Sediment

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Type of sat elite that remains over a fixed point on the earth

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Geostationary

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Sediment is precipitated from seawater

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Hydrogenous Sediment

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Near shore lithogeneous deposits

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Neritic Deposits

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Forms where a plate move over a mantle plume

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Hot Spot

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The most common composition of lithogeneous sediment

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Quartz

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Example of divergent plate boundary

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• East Pacific Ridge
• Red Sea
• Indian Rise
• Mid Atlantic Ridge

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Formed from rain and snow

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Precipitation

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Type of crust that is thick, mostly composed of granite, rich in silicon and aluminum, and has low density

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Continental Crust

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Part of Earth that includes water in solid, liquid, ad gaseous forms

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Hydrosphere

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Ocean Sediments

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• Various materials settle through the water column and accumulate on the ocean floor
• Layers represent a record of Earth history, including:
– Movement of tectonic plates
– Past changes in climate
– Ancient ocean circulation patterns
– Cataclysmic events

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Collection ocean sediments

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• Specially designed ships collect cores by rotary drilling
• Cores allow scientists to analyze ocean sediment

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The 4 main types of sediment

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• Lithogenous = composed of fragments of pre-existing rock material
• Biogenous = composed of hard remains of once-living organisms
• Hydrogenous = formed when dissolved materials come out of solution (precipitate)
• Cosmogenous = derived from outer space

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Origin of Lithogenous sediment

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• Forms by:
– Weathering = breakup of exposed rock
– Transportation = movement of sediment
– Deposition = settling and accumulation

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Lithogenous sediment composition

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• Most lithogenous sediment is composed of quartz, which is:
– Abundant
– Chemically stable
– Durable

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Lithogenous sediment texture

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• Texture includes:
– Grain size
– Sorting
– Rounding
– Maturity

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Distribution of Lithogenous sediment

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• Lithogenous sediment occurs as:
– Neritic (nearshore) deposits
• Beaches
• Continental shelves
• Turbidites
• Glacial-rafted debris
– Pelagic (deep ocean floor) deposits
• Abyssal clay

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Origin of Biogenous sediment

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• Organisms that produce hard parts die
• Material rains down on the ocean floor and accumulates as:
– Macroscopic shells, bones, teeth
– Microscopic tests (shells)
• If comprised of at least 30% test material, called Biogenous ooze

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Biogenous sediment composition

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• Microscopic biogenous tests are composed of 2 main chemical compounds:
• Silica (SiO2) including opal (SiO2 · nH2O)
• Diatoms (algae)
• Radiolarians (protozoan)
• Calcium carbonate or calcite (CaCO3)
• Coccolithophores (algae)
• Foraminifers (protozoan)

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Examples of silica-secreting microscopic organisms
Siliceous ooze

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• Silica-secreting organisms accumulate to form siliceous ooze (>30% siliceous test material)

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Examples of calcite-secreting microscopic organisms
Calcareous ooze

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• Calcite-secreting organisms accumulate to form calcareous ooze (>30% calcareous test material)

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Biogenous ooze turns to rock

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• When biogenous ooze hardens and lithifies, can form:
– Diatomaceous earth (if composed of diatom-rich ooze)
– Chalk (if composed of coccolith-rich ooze)

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Distribution of biogenous ooze

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• Most biogenous ooze found as pelagic deposits
• Factors affecting the distribution of biogenous ooze:
– Productivity (amount of organisms in surface waters)
– Destruction (dissolving at depth)
– Dilution (mixing with lithogenous clays)

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Distribution of siliceous ooze

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• Silica slowly but steadily dissolves in seawater
• Siliceous ooze found where it accumulates faster than it dissolves

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Distribution of calcareous ooze

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• Calcite dissolves beneath the calcite compensation depth (CCD) at 4.5 km
• Calcareous ooze can be found below the CCD if it is buried and transported to deep water

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Origin of hydrogenous sediment

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• Hydrogenous sediment forms when dissolved materials come out of solution (precipitate)
• Precipitation is caused by a change in conditions including:
– Changes in temperature
– Changes in pressure
– Addition of chemically active fluids

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Types of hydrogenous sediment

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• Manganese nodules
• Phosphates
• Carbonates
• Metal sulfides
• Evaporite salts

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Cosmogenous sediment

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• Cosmogenous sediment is composed of material derived from outer space
• Two main types:
• Microscopic space dust
• Macroscopic meteor debris
• Forms an insignificant proportion of ocean sediment

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Mixtures

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• Most ocean sediment is a mixture of sediment types
• One type of sediment usually dominates, allowing it to be classified as primarily:
– Lithogenous
– Biogenous
– Hydrogenous
– Cosmogenous

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Worldwide distribution of neritic and pelagic sediment
Ocean sediments as a resource

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• Ocean sediments contain many important resources, including:
– Petroleum
– Gas hydrates
– Sand and gravel
– Evaporative salts
– Phosphorite
– Manganese nodules and crusts

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Four Types of Sediment

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• There are four basic types of marine sediments, all of which are grouped and ordered by the origin of their particles, the grain sizes, and where they are deposited.
• These four kinds include lithogenous, biogenous, hydrogenous, and cosmogenous. All of these are different from one another in some way but all share in common the tendency to collect along the floor of the oceans as a testament to many natural processes such as weathering, erosion, and collision.

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• Sediments can be classified BY ORIGIN:

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Lithogenous = generated from rocks Hydrogenous = generated from water Biogenous = generated from life

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SEDIMENTS

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• Sediments are typically laid down in layers, or strata, usually in a body of water.
• On the seafloor, sediments are thinnest near spreading centers (young seafloor) and thicker away from the ridge, where the seafloor is older and has more time to accumulate. Sediments are also much thickest near continents.

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Sediments can be classified BY AREA OF DEPOSIT:

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Neritic = deposited on the continental shelf
Pelagic = deposited beyond the continental shelf

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Lithogenous = broken bits of rock (the term "terrigenous" is often used interchangably with "lithogenous")

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- Sediment layers are thickest near the continents, the source of lithogenous material, and thinner farther out to sea. - If you determine that the seds are lithogenous, next check grain size: are they fine, medium or coarse?
Sediments are coarsest near the continental source: the farther from the source, the finer the sediments. - Land areas highest above sea level have the fastest erosion, and the sea floor near mountains will have the most rapid sediment accumulation. - Running water is the main delivery mechanism.
Wet climates have fast erosion on land, and rapid sediment deposition in nearby oceans. Arid regions have slower sedimentation rates.

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Turbidites

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are sediments deposited by underwater landslides (turbidity currents), caused by earthquakes or over-loading of the seds on continental shelf. The seds are sorted out as they flow, and settle in a regular pattern: the coarses particles settle first, then medium, then fine. Repeated sequences of this graded bedding indicates that an are has had many underwater landslides.

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Volcanic ash

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is produced by violent volcanic eruptions. Ash then settles out of the atmosmosphere, through the ocean, and contributes to the sediment column. Where would this type of violent eruption occur?

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Red Clays and Brown Muds

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are very fine-grained, thin sediments found on the abyssal plains, where there isn't much contributing to the sediment column. These are the finest lithogenous particles from the continents, carried a long distance out to sea before settling out.

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Lithogenous

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Lithogenous = broken bits of rock (the term "terrigenous" is often used interchangably with "lithogenous")
- Sediment layers are thickest near the continents, the source of lithogenous material, and thinner farther out to sea. - If you determine that the seds are lithogenous, next check grain size: are they fine, medium or coarse?
Sediments are coarsest near the continental source: the farther from the source, the finer the sediments. - Land areas highest above sea level have the fastest erosion, and the sea floor near mountains will have the most rapid sediment accumulation. - Running water is the main delivery mechanism.
Wet climates have fast erosion on land, and rapid sediment deposition in nearby oceans. Arid regions have slower sedimentation rates.
• Turbidites are sediments deposited by underwater landslides (turbidity currents), caused by earthquakes or over-loading of the seds on continental shelf. The seds are sorted out as they flow, and settle in a regular pattern: the coarses particles settle first, then medium, then fine. Repeated sequences of this graded bedding indicates that an are has had many underwater landslides.
• Volcanic ash is produced by violent volcanic eruptions. Ash then settles out of the atmosmosphere, through the ocean, and contributes to the sediment column. Where would this type of violent eruption occur?
• Red Clays and Brown Muds are very fine-grained, thin sediments found on the abyssal plains, where there isn't much contributing to the sediment column. These are the finest lithogenous particles from the continents, carried a long distance out to sea before settling out.

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Hydrogenous

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precipitate chemically out of seawater. Ions dissolved in seawater combine to form minerals, which precipitate out as solids • Polymetal Sulfides: abundance of metals and sulfur compounds
- ions dissolved from ocean crust by hot water, precipitate when contact cold water; found at present or past sites of hydrothermal vents
• Manganese Nodules: marble-sized to fist-sized lumps, rich in manganese, copper, nickel and silica precipitated from seawater - form a kind of cobblestone pavement on parts of the abyssal plains; always at the top of the sediment column - form where sediment accumulation rate is very slow: far from continents and plate edges, far from biol. productive zones
• Evaporites: layered deposits of salt - form in arid regions; form when a body of seawater becomes isolated, the water evaporates & leaves behind solid salt deposit
• Phosphorite Nodules: small spherical masses rich in phorphorus
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- form on continental shelf mostly, in areas where the concentration of phosphorus in the water exceeds 15%

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Biogenous

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remains of organisms that die, settle to the sea floor
- The vast majority of biogenous particles in marine sediments come from microscopic floating organisms called plankton. - Biogenous seds will be thickest in areas where the water is rich in nutrients (plant food) so that there is abundant biological productivity. - Near coastlines, the biogenous component of sediments may be "diluted" or masked by the rapid input of lithogenous sediments. - If a sediment is > 30% biogenous, we call it an ooze. - If it is an ooze, check the compostion. Is it calcareous ooze or siliceous ooze? The type of ooze depends on two things.
(1) the type of organisms that live in the surface water at that location (2) whether the material dissolves or is decayed as it settles through the water column
• Calcareous ooze: made up mostly of calcium-carbonate (CaCO3) shells - main organisms: coccolithophores (plant plankton) & foraminifera (animal plankton) - note chalky appearance of the CaCO3 tests (shells) under the microscope - CaCO3 -bearing organisms flourish where the surface water is fairly warm
CaCO3 dissolves quickly in cold water, so they are not so abundant where surface water is cold - Calcareous sediments are found mostly on shallow sea floor, because it dissolves as it settles through the cold water in the deep sea
Dissolving of CaCO3 is also affected by water chemistry and pressure (depth) - The level below which we don't see carbonate sediments is called the CCD (Carbonate Compensation Depth).
The depth of the CCD varies: Atlantic Ocean = 5000 m; South Pacific = 4500 m North Pacific = <4000 m
• Siliceous ooze: made up mostly of silica (SiO2) shells - main organisms: diatoms (plant plankton) & radiolaria (animal plankton) - note the fine structure and glassy appearance of the silica tests (shells) under the microscope - these organisms flourish where the surface water is cold, rich & biologically productive. Siliceous oozes are formed under upwelling zones. - Siliceous ooze is found on deeper sea floor, below the level where carbonates have dissolved. - siliceous material also dissolves a bit in seawater, but much more slowly than carbonate material.
• Organic muds = high concentration of organic tissue (the soft parts) -occur where biological productivity at the surface is great, & not all of the organic tissue decays before it is buried in sediment column. - usually black, sticky muds, devoid of oxygen (anoxic); often have that "rotten egg smell" produced by the decay of organics in the seds - marine environments that accumulate organic-rich muds set the stage for the production of an important resource -- hydrocarbons
• Hydrocarbons (oil & gas) are formed when organic material (carbon, oxygen, hydrogen) is buried and chemically converted where - the sedimentation rate is fast enough to bury the organics before they decay away; terrigenous and neritic deposits. - this conversion is speeded up if the heat flow in the area is a little elevated, but not too hot - the fluid oil & gas migrates through sedimentary layers that are "permeable" (have pore spaces that let liquids pass through)
- the geologic environments that have all the necessary requirements for the formation/accumulation of hydrocarbons include ß rifted margins that become passive continental margins: example North Slope of Alaska, Gulf of Mexico / Caribbean Sea ß old river deltas: example in deeper layers of the Mississippi River delta ß marginal sea, behind island arcs: example Bering Sea, Sea of Japan
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ß old ocean basins that are closing up: example Persian Gulf, which is the last remnant of the Tethys that has closed up over time and compressed its sedimentary layers; this area contains 60% of the world's known oil supply.

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Pelagic sediments

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Pelagic sediments, also known as marine sediments, are those that accumulate in the abyssal plain of the deep ocean, far away from terrestrial sources that provide terrigenous sediments; the latter are primarily limited to the continental shelf, and at some point were probably deposited by rivers.[1] Pelagic sediments that are mixed with terrigenous sediments are known as hemipelagic.

There are three main types of pelagic sediments:[2]
1. Siliceous oozes
2. Calcareous oozes
3. Red clays

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Oceanic-oceanic convergence

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As with oceanic-continental convergence, when two oceanic plates converge, one is usually subducted under the other, and in the process a trench is formed. The Marianas Trench (paralleling the Mariana Islands), for example, marks where the fast-moving Pacific Plate converges against the slower moving Philippine Plate. The Challenger Deep, at the southern end of the Marianas Trench, plunges deeper into the Earth's interior (nearly 11,000 m) than Mount Everest, the world's tallest mountain, rises above sea level (about 8,854 m).

Subduction processes in oceanic-oceanic plate convergence also result in the formation of volcanoes. Over millions of years, the erupted lava and volcanic debris pile up on the ocean floor until a submarine volcano rises above sea level to form an island volcano. Such volcanoes are typically strung out in chains called island arcs. As the name implies, volcanic island arcs, which closely parallel the trenches, are generally curved. The trenches are the key to understanding how island arcs such as the Marianas and the Aleutian Islands have formed and why they experience numerous strong earthquakes. Magmas that form island arcs are produced by the partial melting of the descending plate and/or the overlying oceanic lithosphere. The descending plate also provides a source of stress as the two plates interact, leading to frequent moderate to strong earthquakes.

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Continental-continental convergence

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The Himalayan mountain range dramatically demonstrates one of the most visible and spectacular consequences of plate tectonics. When two continents meet head-on, neither is subducted because the continental rocks are relatively light and, like two colliding icebergs, resist downward motion. Instead, the crust tends to buckle and be pushed upward or sideways. The collision of India into Asia 50 million years ago caused the Eurasian Plate to crumple up and override the Indian Plate. After the collision, the slow continuous convergence of the two plates over millions of years pushed up the Himalayas and the Tibetan Plateau to their present heights. Most of this growth occurred during the past 10 million years. The Himalayas, towering as high as 8,854 m above sea level, form the highest continental mountains in the world. Moreover, the neighboring Tibetan Plateau, at an average elevation of about 4,600 m, is higher than all the peaks in the Alps except for Mont Blanc and Monte Rosa, and is well above the summits of most mountains in the United States.



Above: The collision between the Indian and Eurasian plates has pushed up the Himalayas and the Tibetan Plateau. Below: Cartoon cross sections showing the meeting of these two plates before and after their collision. The reference points (small squares) show the amount of uplift of an imaginary point in the Earth's crust during this mountain-building process.

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The earth's continents are constantly moving due to the motions of the tectonic plates. Closely examine the map below, which shows the 15 major tectonic plates.

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As you can see, some of the plates contain continents and others are mostly under the ocean. The type of crust that underlies the continents is called continental crust, while the type found under the oceans is called oceanic crust. Continental crust is thicker — about 20 to 40 miles (35 to 70 km) thick — and usually older than oceanic crust, which is only 4 to 6 miles (7 to 10 km) thick. All the plates have names, usually referring to landmasses, oceans, or regions of the globe where they are located.

Tectonic Plates Map

The border between two tectonic plates is called a boundary. All the tectonic plates are constantly moving — very slowly — around the planet, but in many different directions. Some are moving toward each other, some are moving apart, and some are sliding past each other. Because of these differences, tectonic plate boundaries are grouped into three main types.

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Transform boundaries

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The zone between two plates sliding horizontally past one another is called a transform-fault boundary, or simply a transform boundary. The concept of transform faults originated with Canadian geophysicist J. Tuzo Wilson, who proposed that these large faults or fracture zones connect two spreading centers (divergent plate boundaries) or, less commonly, trenches (convergent plate boundaries). Most transform faults are found on the ocean floor. They commonly offset the active spreading ridges, producing zig-zag plate margins, and are generally defined by shallow earthquakes. However, a few occur on land, for example the San Andreas fault zone in California. This transform fault connects the East Pacific Rise, a divergent boundary to the south, with the South Gorda -- Juan de Fuca -- Explorer Ridge, another divergent boundary to the north.

The Blanco, Mendocino, Murray, and Molokai fracture zones are some of the many fracture zones (transform faults) that scar the ocean floor and offset ridges (see text). The San Andreas is one of the few transform faults exposed on land.

The San Andreas fault zone, which is about 1,300 km long and in places tens of kilometers wide, slices through two thirds of the length of California. Along it, the Pacific Plate has been grinding horizontally past the North American Plate for 10 million years, at an average rate of about 5 cm/yr. Land on the west side of the fault zone (on the Pacific Plate) is moving in a northwesterly direction relative to the land on the east side of the fault zone (on the North American Plate).
San Andreas fault gif

Aerial view of the San Andreas fault slicing through the Carrizo Plain in the Temblor Range east of the city of San Luis Obispo. (Photograph by Robert E. Wallace, USGS.)

Oceanic fracture zones are ocean-floor valleys that horizontally offset spreading ridges; some of these zones are hundreds to thousands of kilometers long and as much as 8 km deep. Examples of these large scars include the Clarion, Molokai, and Pioneer fracture zones in the Northeast Pacific off the coast of California and Mexico. These zones are presently inactive, but the offsets of the patterns of magnetic striping provide evidence of their previous transform-fault activity.

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OCEAN SEDIMENTS

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TYPES (BY SOURCE):
Lithogenous ("rock-derived')
Biogenous ("life-derived")
Hydrogenous ("water-derived")
Cosmogenous ("cosmic-derived")

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COSMOGENOUS SEDIMENTS

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Micro-meteorites

silicates, metals, mixtures
wide-spread, but not abundant

Impacts of large extra-terrestrial bodies (asteroids, comets)

Catastrophic results
Cause of "mass extinctions"? -- dinosaurs

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YDROGENEOUS SEDIMENTS

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(1) Direct precipitation (ppt) from sea water
(2) Sediment - sea water reaction

"Salts" = Dissolved ions in sea water

Evaporation of sea water in "restricted" basins
Ppt. of "salts" -- NaCl (halite) and CaSO4.2H2O (gypsum)

Manganese nodules

Nodules and crusts of Mn & Fe oxides (Cu, Co, Ni) in deep ocean and along mid-ocean ridges.
Origin (?) -- source of metals

Sediments
Sea water
Hydrothermal activity (remember "black smokers")

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LITHOGENOUS SEDIMENTS

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(1) Terrigenous sediments -- continental source

Continental rocks

"Weathering"
-- water - - chemical alteration
-- freeze/thaw cycles
-- wind abrasion

Erosion and transportation
-- streams and rivers
-- wind
-- glaciers

Transport to continental margins (and possibly to Deep-sea floor)

75 % of all marine sediments are lithogenous

Mostly stay ("trapped") on continental margins
Pacific Ocean: terrigenous sediment trapped in margins and trenches; little transported to deep-sea floor.


(2) "Red Clay" -- terrigenous and volcanic ash

Transported to open ocean by winds and surface currents.
Settles through water column -- pelagic clay.
Common in deep oceans where other types are absent.

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BIOGENOUS SEDIMENTS -- produced directly by organisms

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Warm, shallow seas -- shells of animals (clams, corals)
Open ocean (deep sea) -- "shells" of microscopic "plankton"

Components of sediment-producing plankton:

1. CaCO3 (calcium carbonate)

Coccolithophores Foramifera

2. SiO2.(+nH2O) (opaline silica)

Diatoms Radiolarians


Biogenic "oozes" -- > 30% of biogenous sediment

Calcareous ooze
Siliceous ooze

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Distribution of biogenous oozes:

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1. Production in surface waters:

Biological productivity controlled by nutrients -- N and P
"Upwelling" brings nutrients to surface waters
Productivity high in upwelling zones

2. Dissolution in deep waters

Deep waters "undersaturated" -- particles tend to dissolve
"Carbonate Compensation Depth" (CCD)
Calcareous oozes absent below CCD
Atlantic: ~ 4,000 m
Pacific: ~ 500 - 1,500 m
Siliceous particles dissolve more slowly; depth is not an issue

3. Dilution by other sediments

High input of terrigenous sediment
"Dilutes" biogenous components to < 30 %

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SUMMARY -- Distribution of sediment on the sea floor (modern sediments)

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Terrigenous: Continental margins and adjacent abyssal plains.
Manganese nodules: Deep basins, especially the Pacific.
Red Clay: Deep ocean regions where there is very little biogenous or terrigenous sediment
Calcareous oozes: Widespread in relatively shallow areas of the deep sea.
Siliceous oozes: Polar and equatorial bands where nutrients are supplied to surface waters by vertical upwelling.

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Sources and origins of marine sediments

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In the previous lecture, we discussed how sediments are classified according to where they are deposited (neritic, pelagic, etc.) and by their grain size (sand, silt, clay, etc.). Another useful and important classification scheme for classifiying ocean sediments is by their sources, or origins.

In terms of the total volume of ocean sediment, the two most important "types" of sediment in this classification are lithogenous ("rock-derived") and biogenous (produced by marine organisms). Other types are hydrogenous (produced by chemical reactions in sea water) and cosmogenous (particles from outer space). Let's consider those source/origin types in more detail.

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COSMOGENOUS SEDIMENTS

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that accumulate in the oceans (and land) are essentially "micro-meteorites" whose composition can be either silicate (like the mantle), metal (like the core), or a mixture of the two.
- Although there is a continuous "rain" of these particles on Earth, cosmogenous sediments make up a very minor component of ocean sediments -- in fact, it takes an expert to identify them.
- But throughout the history of our planet, very large extra-terrestrial bodies (large meteorites, asteroids, even comets) have collided with the Earth from time to time.
- The results are catastrophic! -- a large, deep crater; molten rock and ash ejected into the atmosphere, world-wide fires.
- Many scientists have concluded that major impacts cause "mass extinctions," like the extinction of the dinosaurs and 80% of all living species 65 m.y. ago.

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HYDROGENEOUS SEDIMENT

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(1) direct precipitation from sea water, or
(2) as a new mineral from chemical reactions between sea water and
sediments on the sea floor

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Manganese nodules

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are oxides of the metals manganese (Mn) and iron (Fe). They also contain minor amounts of copper (Cu), cobalt, (Co), and nickel (Ni).
- Manganese nodules occur as nodules and crusts, primarily in deepest of oceans and near mid-ocean ridges.
- Their origin is controversial. We do not know the source of the metals nor how and why they are concentrated in nodules.
- The metals may be delivered as dissolved species or as sediments from land.
- A more likely origin is volcanic activity and hydrothermal alteration of ocean crust at mid-ocean ridges. Remember the "black smokers?" Much of the suspended particles are Mn and Fe oxides.

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HYDROGENEOUS SEDIMENTS

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(1) direct precipitation from sea water, or
(2) as a new mineral from chemical reactions between sea water and
sediments on the sea floor

"Salts" - - Sea water contains dissolved ions (about 3.5 % by weight).
- When sea water undergoes extensive evaporation in bays or even large seas that are restricted from "communicating" (circulating) with the "open" ocean, the concentration of ions can increase to the point where they are "saturated" with respect to certain solids that we simply call "salts."
- Important sea salts are NaCl (halite) and CaSO4.2H2O (gypsum).
- Salts precipitate from "super-saturated" sea water in restricted basins and are deposited on the sea floor.

"Manganese nodules" - - are oxides of the metals manganese (Mn) and iron (Fe). They also contain minor amounts of copper (Cu), cobalt, (Co), and nickel (Ni).
- Manganese nodules occur as nodules and crusts, primarily in deepest of oceans and near mid-ocean ridges.
- Their origin is controversial. We do not know the source of the metals nor how and why they are concentrated in nodules.
- The metals may be delivered as dissolved species or as sediments from land.
- A more likely origin is volcanic activity and hydrothermal alteration of ocean crust at mid-ocean ridges. Remember the "black smokers?" Much of the suspended particles are Mn and Fe oxides.

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Terrigenous sediments

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are produced by the physical and chemical "weathering" (alteration) of rocks exposed on continents. Sedimentary particles are then eroded and transported from land to the oceans. Most sediment is carried by rivers, but winds and glaciers are also important transport agents. River-transported sediment is deposited on continental margins and mostly stays there. Only a small fraction is transported to the open ocean (e.g., by turbidity currents).

Terrigenous sediments make up 75 % of all the sediment that is deposited in the ocean. The thickest accumulations (up to 10 km!) occur in continental rises. But keep in mind that most terrigenous sediment remains on continental margins -- river deltas, bays, estuaries, as well as continental rises. In the Pacific, sediment from land is trapped in those environments and in marginal trenches. As a consequence, relatively little terrigenous sediment is transported to the deep-sea floor of the Pacific.

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LITHOGENOUS SEDIMENTS

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in the ocean come in two varieties: (1) terrigenous ("land-derived") and (2) "red clay."

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SUMMARY -- Distribution of sediment on the sea floor (modern sediments)

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Terrigenous: - - continental margins and adjacent abyssal plains.
Manganese nodules: - - deep basins, especially the Pacific.
Red Clay: - - deep ocean regions where not diluted by biogenic particles.
Calcareous oozes: - - wide-spread in relatively shallow areas of the deep sea.
Siliceous oozes: - - polar and equatorial bands where nutrients are supplied to surface waters by vertical upwelling.

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(Divergent)

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- where two plates move away from each other resulting in new crust being formed.

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(Convergent)

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- where two plates move towards each other - in the case of a plate consisting of continental crust meeting a plate consisting of oceanic crust, the oceanic crust will be subducted and destroyed as it is less dense.

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Convergent boundaries.

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Plates may converge directly or at an angle. Three types of convergent boundaries are recognized:
• continent-continent
• ocean-continent
• ocean-ocean.