PLATE TECTONICS:

A UNIFYING THEORYGeology

The Walker School

Earth’s crust is about 5% of it’s mass.

Oceanic Crust

5 to 8 km thick.

Composed mainly of basalt

and gabbro.

Not older than 180 million

years.

Covered with dead organism

and sediment, about 1 km

thick.

Little variability in

composition.

Continental Crust

Composed of many

rock types.

Can be as old as 4

billion years.

Varies in thickness

from 20 to 80 km.

Makes up about 41%

of Earth’s surface.

Cratons are the oldest parts of the

continents.

Crust is made of 10 Major Plates

Fig. 1-11, p. 17

Activity Along Plates

Volcanism

Earthquakes

Mountain Building

Basin Formation

Plate Activity

Fig. 1-12, p. 18

Composite Satellite Image of

Himalayan Peaks

Interactions Between Plates and Climate

Movement between Plates

Location of Continents and Ocean

Basins

Colliding Plates Create

Mountains

Mountain Shape and Size Affect Atmospheric Circulation

Ultimately Affects Global Climate

WHAT IS CONTINENTAL

DRIFT?

Alferd Wagner Proposed the Theory

of Continental Drift

Fig. 2-2, p. 35

Evidence for Continental Drift

Shorelines of Continents

Similar Rock Sequences

Similar Mountain Ranges

Matching Glacial Deposits

Similarity in Extinct Plants and Animals

Shorelines of Continents

Fig. 2-3, p. 36

Similar Rock Sequences

Fig. 2-4, p. 37

Trends of Mountain Ranges

Glacial Evidence from Striations

Fig. 2-5, p. 38

Fossil Evidence

Fig. 2-6, p. 39

TYPES OF PLATE

BOUNDARIES

Types of Plate Boundaries

Table 2-1, p. 47

DIVERGENT PLATE

BOUNDARIES

Mid-Atlantic Ridge

Fig. 2-10, p. 43

Earth’s Magnetic Field Recorded in

Oceanic Crust

Fig. 2-11, p. 44

Fig. 2-12, p. 45

Red:

48

MYAYello

w: 68

MYA

Green:

155

MYA

Age of the World’s Oceans

Sediments Increase Away from

Ridges Toward Continents

Fig. 2-13, p. 45

Divergent

Plates Form

Oceans

Fig. 2-15, p. 48

East African

Rift Valley

Formed from

Divergent

Plates

Fig. 2-16a, p. 49

Red Sea: Example of Adv. Rifting

Fig. 2-16b, p. 49

Indicators of Rifting

Faults

Dikes (Vertical Intrusions of Magma)

Sills (Horizontal Intrusions of Magma)

Lava Flows

Thick Sedimentary Sequences

Pillow Lava

Pillow Lavashttp://www.youtube.com/watch?v=xsJn8izcKtg

Example of Paleo-Rifting in the United States

Hudson River Valley: Palisades, NJ

Fig. 2-17, p. 52

CONVERGENT PLATE

BOUNDARIES

Oceanic Plate Boundaries

Fig. 2-18a, p. 53

Oceanic-Continent

Plate Boundaries

Fig. 2-18b, p. 53

Continental-Continental

Fig. 2-18c, p. 53

Indicators of Convergence

Melange

Ophiolites

TRANSFORM FAULTS

Most transform faults connect two oceanic

ridges.

Fig. 2-20a, p. 56

A transform fault can connect a ridge and

a trench.

Fig. 2-20b, p. 56

A transform fault can link two ridges.

Fig. 2-20c, p. 56

San Andres Fault

Fig. 2-21, p. 57

HOT SPOTS: AN

INTRAPLATE FEATURE

Mantle Plumb remains stationary while

plates move.

Fig. 2-22, p. 58

PLATE MOVEMENT

Plates, Zones, and Movements

Fig. 2-14, p. 46

Methods for determining movement.

Measuring age of sediment.

Dating magnetic anomalies on the seafloor.

Satellite-Laser ranging techniques.

Hotspots

Supercontinent Cycle

DRIVING MECHANISM OF

PLATE TECTONICS

Fig. 1-10, p. 16

Model I: Thermal convection cells are

restricted to the asthenosphere.

Fig. 2-24a, p. 60

Model II: Thermal convection cells involve

the entire mantle.

Fig. 2-24b, p. 60

DISTRIBUTION OF NATURAL

RESOURCES

Mineral Deposits Associated with

Plate Boundaries

Fig. 2-26, p. 62

Fig. 2-25, p. 61

Mineral Formation Processes

Sedimentation (coal)

Precipitation (salts, metals)

Crystallization from Magma Plutons (ores)

Changes in Temperature and Pressure (ores)

Fluid Inclusions (ores)

Greatest Copper Deposits

The greatest known deposit of copper is in

porphyries formed by volcanic activity in the Chile's

Andean Mountains.

Chile's copper mines provide over 30% of the

world's mine production of recoverable copper.

Escondida Copper Mine is today the world's

largest producing mine with 750,000 metric tons of

production which was 5.6% of the world's

production in 2000.

Escondida Copper Mine, Chili

The Escondida copper-

gold-silver mine is

located in the arid,

northern Atacama

Desert of Chile about

160km southeast the

port of Antofagasta, at

an elevation of 3,050m

above sea level.

Copper is the Oldest Minded Mineral

Copper is mankind's oldest metal, dating back more

than 10,000 years.

A copper pendant discovered in what is now

northern Iraq goes back to about 8700 BC.

Archeologists have recovered a portion of a water

plumbing system from the Pyramid of Cheops in

Egypt. The copper tubing used was found in

serviceable condition after more than 5,000 years.

Copper was mined in Ancient Rome

Copper was named for

the island of Cyprus,

where the Romans

obtained their supply.

Copper in Early America

When Columbus sailed to the Americas, his ships,

Nina, Pinta and Santa Maria, had copper skins

below the water line. The copper sheathing

extended hull life and protected against barnacles

and other kinds of biofouling.

Paul Revere, produced the bronze cannon, spikes

and pumps for the famous ship, Old Ironsides.

Revere was one of the earliest American

coppersmiths.