Plate Tectonics

Plate Tectonics

MajorDivisionsof Earth

Plate Tectonics

DifferentProperties

Plate Tectonics

Rigid

Plate Tectonics

Plastic

The outer layer is the thinnest

= Crust

Two kinds of Crust

Plate Tectonics

• continental crust:

thicker, light

(granite)

• oceanic:thinner, dense

(basalt)

Plate Tectonics

2.7g/cm³

3.3 g/cm³

• Each Tectonic Plate: Oceanic crust

or

Oceanic & Continental crust

Plate Tectonics

• Each Tectonic Plate: Oceanic crust

or

Oceanic & Continental crust

(none with continent only)

Plate Tectonics

• Oceanic crust or

Oceanic & Continental crust

Plate Tectonics

• Active continental margin:

leading edge of plate

(earthquakes, volcanoes, steep mountains)

Plate Tectonics

• Passive continental margin:

trailing edge of continent

(eroded mountains, flat plains, little activity)

Plate Tectonics

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Plate Tectonics

Classification of Plate Boundaries

Plate Tectonics

I. Divergent Boundaries: • tension = pull apart

• normal faults

Plate Tectonics

I. Divergent Boundaries: • tension = pull apart

• normal faults

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Plate Tectonics

I. Divergent Boundaries: • new ocean crust formed • mid-ocean ridge with a rift valley down the middle

Plate Tectonics

I. Divergent Boundaries:

young basin

Plate Tectonics

I. Divergent Boundaries:

mature basin

Plate Tectonics

I. Convergent Boundaries:

• compression = push

together

• reverse faults

Plate Tectonics

I. Convergent Boundaries:

• compression = push

together

• reverse faults

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Plate Tectonics

I. Convergent Boundaries:

• folding & uplift earthquakes

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Plate Tectonics

Three kinds of

Convergent Margins(Crust Type)

oc - ococ - cont.

cont. - cont.

Plate Tectonics

IIa. Ocean - Ocean

• deep sea trench

• subduction zone (recyle)

• volcanoes & uplift

Aleutians, Japan, Philippines, Indonesia

Plate Tectonics

IIb. Ocean - Continent

• deep sea trench

• subduction zone (recycle ocean side)

• volcanoes & major uplift

Plate Tectonics

IIb. Ocean - Continent

Andes, Cascades

Plate Tectonics

IIc. Continent - Continent

• collision

• no subduction, no vulconism (can't recyle continents)

• heat & pressure, folding & major uplift

Plate Tectonics

IIc. Continent - Continent

Himalayas

Plate Tectonics

III. Transform Plate boundaries

• shear = sliding past in opposite directions

• lateral movement with earthquakes

Plate Tectonics

III. Transform Plate boundaries

CaliforniaSan Andreas fault