Slide 1

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 2

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 3

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 4

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 5

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 6

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 7

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 8

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 9

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 10

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 11

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 12

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 13

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 14

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 15

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 16

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 17

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 18

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 19

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 20

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 21

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 22

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 23

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 24

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 25

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 26

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 27

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 28

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 29

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 30

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 31

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 32

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 33

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 34

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 35

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 36

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 37

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs


Slide 38

Plate Tectonics
• Alfred Wegener – early 1900’s proposed the concept of
Continental Drift- the continents were once joined a large
“super continent” called Pangaea
– Evidence
•
•
•
•

Continental Jigsaw
Fossils
Ancient Climates- study of Paleozoic Rocks (200-300 million years ago
Mountain Ranges

– Problems
• Work was mostly completed in the southern hemisphere- vast majority of
geologists worked in the northern hemisphere
• He could not produce a mechanism

Paleoclimatic evidence for Continental
Drift

Wegener’s matching of mountain
ranges on different continents

Pangaea approximately 200 million
years ago
• Breakup of Pangaea figure 19.2

• It was not until 1950’s and 1960’s when
Wegener’s theories were revised through the
study of the sea floor topographic features,
the geophysics of earth interior and paleomagnetics of the rock on the ocean floor

1950’s and 60’s
• Geophysical data– seismic data about the earth’s interior
– Paleomagnetic data
– Topography of the sea floor

• Additional data
– Rock samples from the sea floor
• Absolute dating of seafloor basalts

– Images of the deep sea floor

Deep Wells
• 1970: Kola super deep borehole in Kola Peninsula, Russia 7.6 mile planed
9.3 miles
• 1999 Hawaii Scientific Drilling, Project Hilo, Hawaii. 1.8 mile of planned 2.8
miles into flank of Mauna Kea, Hawaii- magma movement and magnetic
changes
• 2004: San Andreas Scientific drilling Parksfield California 2.5 miles into San
Andreas Fault buried sensors
• 2004: Integrated Ocean Drilling Project: Atlantis Massif Region of the
Atlantic Ocean: .9 miles goal to penetrate earth’s mantle but crust proved
thicker than anticipated
• 2006:1.5 mile bore hole into an impact crater at the mouth of Chesapeake
Bay Cape Charles, Virginia

Data collection

Cameras

The Harry Hess Hypothesis: Sea Floor
Spreading ( Mechanism!)
– Hypothesis sea floor moves away from the mid oceanic
ridge crests and to the trenches as a result of mantle
convection
– Evidence
– Geophysical evidence of mantle convection
– Ridge crest high heat flow- basalt eruptions
– Trenches low heat flow
– Ridge Crests (spreading axis) have thin or little palagic
sediment
– Age of the sea floor ( 200 million years old)

1960’s The Mechanism- Sea Floor
Spreading
• further support of the Plate Tectonic Theory comes
from the work of Fred Vine and Drummond
Matthews
• Vine and Matthews discovered from gravity and
magnetic surveys of the ocean floor that there was a
regular pattern of magnetic anomalies that were
symmetrical. The pattern of magnetic anomalies of
the mid-oceanic ridge was the same on both sides of
the ridge.

Vine and Matthews Study of the
Magnetism of Seafloor Rocks
– On the ocean floors magnetic reversals occur in a
regular pattern that is mirrored on both sides of
the mid-oceanic ridges
–
– Magnetic reversals have since been dated from
land; the anomalies at the sea floor caused by the
reversal is also dated and its distance from the
spreading center or ridge is measured and the rate
at which it has moved can be calculated

Paleomagnetic reversals recorded by
basalt at mid-ocean ridges
• Paleomagnetic Reversals

Predicting the age of the sea floor
• Magnetic reversals are known to have
occurred back to Precambrian time.
• The sequence of marine magnetic anomalies
has been established for the past 160 million
years and forms a distinctive pattern.
• It is documents on the ocean floor as well as
on land

Additional Evidence
• Earthquake Patterns- associated with plate boundaries
• Deep sea drilling projects- the first in 1968 –The Glomar Challengerdiscovered that the ocean floor was only 180 million years old- mostly
made up of basalt- also ocean floor got older as you moved away from the
mid-oceanic ridges
• Mantle Hotspots- Hawaii (islands seamounts and guyot)
– Emperor seamount chain – 40 million years ago change in direction of Pacific
plate movement

• Re-fit of the continental jigsaw using the continental slope break

Deep-focus earthquakes occur along
convergent boundaries

Earthquake foci in the vicinity
of the Japan trench

The Hawaiian Islands have formed
over a stationary hot spot
• Mantle Hot Spots (figure 19.46)

The Plate Tectonic Model
• includes the concepts of:
– Continental Drift
– Mantle Convection
– Sea Floor Spreading
– Paleomagnetic Reversals
• supported by data:
– age of the ocean floor

– distribution for earth quakes and volcanoes
– relative thickness and types of sediment
• Plate Tectonic Theory!

The PT Model
• The upper part of the upper mantle and the
crust make up the lithosphere which is rigid or
solid
• The lower part of the upper mantle is the
asthenosphere which is weaker (plastic)
• The lithosphere is broken into a series of rigid
plates which moving and changing size and
shape. The lithosphere is balanced on the
asthenosphere

Plates
• Plates move at a rate of 1-10cm per/yr
– The Breakup of Pangaea (figure 19.2)

• Seven big plates and many smaller plates
–
–
–
–
–
–
–

North American
South American
Pacific-largest
African
Eurasian
Australian
Antarctica

Caribbean
Nazca
Phillippine
Arabian
Cocos
Scotia

Three Types of Plate Boundaries
• Divergent- plates moving apart – mantle is
closer to the surface – magma is cooling on
the seafloor creating new oceanic crust
– Divergent Plate Boundary (figure 19.21)

• Convergent- two plates are coming together– Oceanic-Continental Convergence to Continental-Continental Convergence

• Transform Fault - Plates moving past each
other- strike slip

Divergent Plate Boundaries
• Mid-oceanic ridges- spreading axis
• Seafloor spreading• Rifts and rift valleys– The Red sea- East African Rift valley

Divergent boundaries are located
mainly along oceanic ridges
• Divergent Lithosphere Plate Boundary (figure 19.21)

The East African rift – a
divergent boundary on land
The Red Sea -NASA

^N

Convergent Plate Boundaries
• Classified based on the type of plates involved
• Oceanic plate are made of basalt more dense
than continental crust. Denser plates moves
“subduct” under less dense plate
– Continental-Oceanic Convergent Boundary
– Oceanic-Oceanic Convergent Boundary
– Continental-Continental Convergent Boundary

Oceanic –Continental Convergence
• Continental volcanic arcs– Examples : The Andes Mountains and the Cascade Range,
– Oceanic-Continental Convergence (figure 19.32)

Oceanic-Oceanic convergence
• Volcanic island arcs– Atlantic Ocean Lesser Antilles, Sandwich Islands
– Pacific Ocean- Aleutian islands, Mariana and Tonga
islands
– 120-180 mile arc-trench gap
– Oceanic-Oceanic Convergence

Continental-Continental Convergence
• Continental crust converge with continental
crust
• Mountain building !!!!
– Example- Himalayas, Alps. Appalachians, Urals
– Continental-Continental Convergence (figure 19.33)

The collision of India and Asia produced
the Himalayas ( Breakup of Pangaea)

Transform Fault Lithospheric Plate
Boundaries
• Most are fracture zones on mid –oceanic
ridges- approximately every 100 km (60 miles)
• San Andres is unusually because it cuts
continental crust

Example 4: The San Andreas Fault
System
a major transform fault lithospheric plate
boundary

UC Santa Barbara Models
West Coast North America
•
•
•
•
•

sm01PacN.mov (80 MYA- Present)
sm02Pac-NoAmflat.mov (40 MYA –Present)
sm16OldWestNoAm.mov (20 MYA- Present)
sm03socalcities.mov (20 MYA- Present)
sm12Plplshortening.mov (model)

UT Models

The Driving Mechanism for Plate Tectonics
• Three concepts:
– Mantle Convection
– Slab-Push and Slab-pull

– Rising Plumb and Descending Slabs